III.
Red Oil 33-1/3 " Corn Oil 33-1/3 " Cocoanut Oil or Palm Kernel Oil 33-1/3 "
SOAPS USED IN THE SILK INDUSTRY.
Soap is used to a very large extent in silk mills, both for degumming the raw silk and in silk dyeing. Raw silk consists of the true silk fibre known as fibroin and a gummy coating, sericin, which dulls the lustre of the silk unless removed. For this purpose a slightly alkaline olive oil foots soap is best adapted, although palm oil and peanut oil soaps are sometimes used, as well as soaps made from a combination of house grease to the extent of 30 per cent., together with red oil or straight olein soaps, both of which are artificially colored green. In using house grease, if 30 per cent. is exceeded in combination with red oil, the titer is raised to such an extent that the soap does not readily rinse from the silk nor dissolve readily. They are also not advisable because they impart a disagreeable odor to the silk.
To make a soap for this purpose from olive oil foots it is made as a settled soap, care being taken to thoroughly boil the mass on the saponification change in the closed state to assure proper saponification. The kettle is usually grained with lye and given a good wash change to remove the excess strength. The change previous to the finish should not be too heavy or too large a nigre results. The lighter the grain is, the better the finished kettle is. A yield of 150 per cent. is usually obtained. This soap is generally run to a frame, slabbed upon cooling and packed directly into wooden cases.
For silk dyeing the above soap is suitable, although any well-made soap of good odor and not rancid is useable. While soap alone is often used in the bath for silk dyeing, certain dyestuffs require the addition of acetic or sulphuric acid, which sets free the fatty acids. If these be of bad odor it is taken up by the silk and is difficult to remove. The most generally used soaps are the just mentioned olive foots soap or a soap made from a good grade red oil.
Both kinds are extensively used.
SOAPS USED FOR COTTON GOODS.
In the manufacture of cotton goods, as compared to the wool and silk industries, very much less soap is used and it is only applied to the finished fabric either to clean the cloth preparatory to dyeing or to aid in dyeing with certain colors. It is also used in calico printing. For cleansing the cloth ordinary chip soap is suitable although a more alkaline soap finished as a curd soap is an advantage in that the free alkali contained therein aids in removing the dirt and has no harmful effect on the cotton. For dyeing cotton goods or to brighten certain colors after dyeing an olive oil foots soap is most generally employed. In calico printing soap is used to wash and clear the cloth after printing. A soap for this purpose should be easily soluble in water and contain no free alkali, rosin or filler. The best soaps for use in calico printing are either an olive oil foots soap or an olein soap.
SULPHONATED OILS.
While sulphonated oils are not used to any great extent in the manufacture of soap, they are used very largely in the dyeing and printing of turkey and alizarine reds on cotton as well as other colors. Just what action these oils have is not known. Turkey red oil or sulphonated castor oil is the best known sulphonated oil.
The process of making these oils is simple. The equipment necessary is a wooden tank or barrel of suitable capacity, approximately two and a half times the amount of oil to be treated. There are furthermore required other tanks or vessels to hold the solutions used such as caustic soda, ammonia and acid. The tank to be used for the preparation of sulphonated oil should be provided with a valve at the bottom of the tank and a gauge to measure the quantity of liquid therein.
The process is carried out as follows:
Three hundred pounds of castor oil are placed in the tank and 80 pounds at 66 deg. B. sulphuric acid are weighed out in another vessel. The acid is run into the tank containing the oil in a very thin stream while the oil is well stirred. At no time should the temperature exceed 40 deg. C. This operation should consume at least an hour and stirring should be continued half an hour longer to insure the thorough mixing of the oil with the acid. The mass is then allowed to settle for 24 hours, after which 40 gallons of water are added and the mixture stirred until it has a uniform creamy color indicating no dark streaks. This mixing process should be carefully carried out and when completed allowed to settle 36 hours. At this point the mass will have separated into two layers, the lower layer consisting of a water solution of acid and the upper layer of oil. The former is run out through the valve located at the bottom of the tank. Another wash may now be given or dispensed with as desired. In this wash the addition of salt or sodium sulphate at the rate of 1-1/2 pounds per gallon of water is advisable. A 24 deg. B. caustic soda solution is prepared and added slowly to the acidified oil with constant stirring. The mass first turns creamy, then becomes streaked, increasing in streaks as the caustic solution is poured in, and finally becomes clear and transparent. Water is now added to bring the volume to 75 gallons. The oil is now milky in appearance, but the addition of a little more soda solution restores the transparency.
In some cases ammonia is used in addition to caustic soda in neutralizing the oil. Three-fourths of the amount of caustic soda required to complete the neutralization is first added and then the neutralization is completed with a one to one liquid ammonia and water solution.
FOOTNOTES:
[9] Seifensieder Ztg., 40, 47, 1266 (1913).
[10] Seifensieder Ztg. (1913), p. 334 and 338. " " (1912), p. 1229 and 1257.
[11] Seifensieder Ztg. (1912), p. 954.
## CHAPTER V
Glycerine Recovery.
The recovery of glycerine is very closely allied with the soap-making industry, because glycerine is the very valuable by-product obtained in the saponification of oils and fats. No soap plant is, therefore, fully equipped unless it has some method whereby the glycerine is recovered and the importance of recovering this product cannot be too strongly emphasized.
It has already been pointed out that neutral fats or the glycerides are a combination of fatty acid with glycerine. These are split apart in the process of saponification. While by the term _saponification_ as used in soap making it is inferred that this is the combination of caustic alkalis with the fatty acids to form soap, this term is by no means limited to this method of saponification, as there are various other methods of saponifying a fat. The chemical definition of saponification is the conversion of an ester, of which glycerides are merely a certain type, into an alcohol and an acid or a salt of this acid. Thus, if we use caustic alkali as our saponifying agent for a fat or oil, we obtain the sodium or potassium salt of the higher fatty acids or soap and the alcohol, glycerine. On the other hand, if we use a mineral acid as the saponifying agent, we obtain the fatty acids themselves in addition to glycerine. While the former is by far the most generally employed for making soap, other processes consist in saponifying the fats by some method other than caustic alkalis and then converting the fatty acids into soap by either neutralizing them with sodium or potassium carbonate or hydrate.
It is important to again point out here that fats and oils develop free fatty acid of themselves and that the development of this acid represents a loss in glycerine. The selection of an oil or fat for soap making should therefore to a large extent be judged as to its adaptability by the free fatty acid content, as the higher this content is, the greater is the loss in the glycerine eventually obtained. Glycerine often represents the only profit to a soap manufacturer. It is indeed necessary to determine the percentage of free fatty acid before purchasing a lot of stock to be made into soap.
In taking up the question of glycerine recovery we will consider the various methods thus:
1. Where the glycerine is obtained from spent lye by saponifying the fats or oils with caustic alkali.
2. Where the glycerine is obtained by saponifying the fats or oils by some other method than the above, of which there are the following:
(a) Twitchell process. (b) Saponification by lime in autoclave. (c) Saponification by acid. (d) Saponification by water in autoclave. (e) Fermentative (Enzymes). (f) Krebitz process.
RECOVERY OF GLYCERINE FROM SPENT LYE.
The spent lye obtained from the glycerine changes in making soap varies greatly, the quality depending upon the stock saponified and the soap maker's care in handling the operation. No two lyes run exactly alike as to proportion of the various ingredients, although they are all similar in containing the same substances either in solution or suspension. Spent lye is a water solution of mainly glycerine, free alkali either as caustic alkali or carbonate and salt, including sodium sulfate, but furthermore contains some soap and albuminous matter either in solution or suspension. Upon standing in the storage tank the greater part of the soap usually separates when the lye cools. In order to assure the greatest economical yield of glycerine by saponifying a fat with caustic soda it is necessary to obtain a proportion of three parts of water to every part of fat made into soap. Test runs have shown that this is the proper proportion and that it is not economical to greatly exceed this amount, and if a much less proportion is used the full yield of glycerine is not obtained.
The spent lyes contain varying amounts of glycerine, the first change being richest in glycerine content, and this being reduced in the subsequent changes. If the lyes always run high in glycerine it is an indication that it is not all being obtained. The usual percentage is from 0.5% to 5% or even more, although the average is somewhere around 2% to 3%. The lye as it comes from the kettle should not contain any more than 0.5% to 0.6% of free alkali calculated as sodium carbonate, Na_{2}CO_{3}. If the proportion is higher than this, it shows that the saponification has been conducted with too high a proportion of alkali, a condition which should be corrected in the kettle room. An excess of free alkali does not interfere to any great extent with the successful recovery of the glycerine, but is a waste of both alkali and the acid used in neutralizing this. It is, therefore, more economical to run a strong lye over fresh stock and neutralize the alkali thus, rather than treating the lye for glycerine recovery.
Before the spent lye can be run into the evaporator it is necessary to remove the albuminous impurities and soap and to neutralize the excess alkali to between exactly neutral and 0.02% alkalinity. The lye should never be fed into the evaporator in the acid condition.
In order to treat the spent lyes for evaporation, they are first allowed to cool in the storage tank, after which any soap which may have separated is skimmed off and returned to the soap kettle. This lye is then pumped to the treatment tank, an ordinary tank equipped with some method of agitating the liquor, either by a mechanical stirrer, steam blower or compressed air, until it is about two feet from the top.
After the lye has been skimmed off it is thoroughly agitated and a sample taken. The amount of lye in the tank is then calculated. Spent lye is about 1.09 times heavier than water, or weighs about 9 pounds to the gallon. While the sample is being tested for alkalinity it is advisable to add sulfate of alumina, which may be dissolving while the sample is being titrated. This substance should be added in the proportion of anywhere from 6 to 14 pounds per thousand pounds of lye, depending upon the amount of impurities contained therein. For a clean lye six pounds per thousand is sufficient, but for an impure lye a greater quantity is necessary. The sulfate of alumina used should be free from arsenic and sulfides and should contain a minimum amount of grit (silica), as grit reduces the life of the pump valves. This may be estimated with sufficient accuracy by rubbing the filtered-off portions, insoluble in water between the fingers and a plate of glass. The object of adding the sulfate of alumina is to transform the soap contained in the lye into the insoluble aluminum soaps, and at the same time to coagulate the albuminous impurities. It must be remembered that the sulfate of alumina is added only for the fresh lye put into the tank. Thus if there were 10,000 pounds of lye in the treating tank when the fresh lye was run in, and 50,000 pounds when the tank is filled, adding nine pounds of sulfate of alumina per thousand of lye, only 360 pounds would be added or enough for 40,000 pounds. Sulfate of alumina neutralizes one-third of its weight of caustic.
To determine the alkali in the sample, 10 cubic centimeters are pipetted into a beaker, a little distilled water added, then 3 or 4 drops of phenolphthalein indicator. From a burette, quarter normal (N/4) sulfuric acid is added until the pink color is just discharged. When this point is reached 4 to 5 c. c. more of acid are added and the solution is boiled to expel the carbon dioxide. Should the solution turn pink, it is necessary to add more acid. After having boiled for 3 to 4 minutes, N/4 caustic soda is added until the pink color just returns and the amount of caustic soda used is read on the burette. The difference between the number of cubic centimeters of N/4 sulfuric acid and N/4 caustic soda gives the amount of alkali in the sample. By using a 10 c. c. sample and N/4 sulfuric acid and N/4 caustic soda each c. c. obtained by the difference of these two solutions is equal to one-tenth of one per cent. (0.1%) of the total alkali in the lye. As an example, say we first used 7.7 c. c. of N/4 sulfuric acid to just discharge the pink, then added 4 c. c. more, or 11.7 c. c. in total. After boiling it required 5.3 c. c. to bring back a slight pink, the total alkalinity would be 11.7 c. c. - 5.3 c. c. = 6.4 c. c., or 0.64% total alkali in the lye in terms of caustic soda. If there were 40,000 pounds of lye to be treated then we should have to neutralize:
40,000 x .0064 = 256 lbs. alkali. Since sulfate of alumina neutralizes one-third of its weight in caustic, and there are say 9 lbs. of this added per thousand pounds of lye we would add
40,000 x 9 = 360 lbs. of sulfate of alumina. This would neutralize 360 x 1/3 = 120 lbs of alkali. There are then 256 - 120 = 136 lbs. of alkali still to be neutralized. If 60deg. B. sulfuric acid is used it requires about 1.54 lbs. of acid to one pound of caustic. Therefore to neutralize the caustic soda remaining it requires:
136 x 1.54 = 209.44 lbs. 60deg. B. sulfuric acid to neutralize the total alkali in the 40,000 pounds of spent lye.
The acid is added and the lye well stirred, after which another sample is taken and again titrated as before. From this titration the amount of acid to be added is again calculated and more acid is added if necessary. Should too much acid have been added, caustic soda solution is added until the lye is between exactly neutral and 0.02% alkaline. The filtered lyes at this stage have a slight yellowish cast.
To be sure that the lyes are treated correctly the precipitation test is advisable. To carry this out filter about 50 c. c. of the treated lye and divide into two portions in a test tube. To one portion add ammonia drop by drop. If a cloudiness develops upon shaking, more alkali is added to the lye in the tank. To the other portion add a few drops of 1 to 5 sulfuric acid and shake the test tube. If a precipitate develops or the solution clouds, more acid is needed. When the lyes are treated right no cloudiness should develop either upon adding ammonia or the dilute acid.
The properly treated lye is then run through the filter press while slightly warm and the filtered lye is fed to the evaporator from the filtered lye tank. The lye coming from the filter press should be clear and have a slight yellowish cast. As the pressure increases it is necessary to clean the press or some of the press cake will pass through the cloths. Where sodium silicate is used as a filler, the silicate scrap should never be returned to the soap kettle until the glycerine lyes have been withdrawn. This practice of some soapmakers is to be strongly censured, as it causes decided difficulty in filtering the lye, since during the treatment of the lye, free silicic acid in colloidal form is produced by the decomposition of the sodium silicate by acid. This often prevents filtering the treated lye even at excess pressure and at its best retards the filtering.
As to the filter press cake, this may be best thrown away in a small factory. Where, however, the output of glycerine is very large it pays to recover both the fatty acids and alumina in the press cakes.
In some cases, especially when the lyes are very dirty and the total residue in the crude glycerine runs high, for which there is a penalty usually attached, a double filtration of the lye is advisable. This is carried out by first making the lye slightly acid in reaction by the addition of alum and acid, then filtering. This filtered lye is then neutralized to the proper point with caustic, as already described, and passed through the filter press again.
While in the method of treating the lyes as given sulfuric acid is used for neutralizing, some operators prefer to use hydrochloric acid, as this forms sodium chloride or common salt, whereas sulfuric acid forms sodium sulfate, having 3/5 the graining power of salt, which eventually renders the salt useless for graining the soap, as the percentage of sodium sulfate increases in the salt. When the salt contains 25 per cent. sodium sulfate it is advisable to throw it away. Sulfuric acid, however, is considerably cheaper than hydrochloric and this more than compensates the necessity of having to eventually reject the recovered salt. It may here also be mentioned that recovered salt contains 5-7 per cent. glycerine which should be washed out in the evaporator before it is thrown away. The following tables give the approximate theoretical amounts of acids of various strengths required to neutralize one pound of caustic soda:
For 1 pound of caustic soda--
3.25 lbs. 18deg. B. hydrochloric (muriatic) acid are required. 2.92 " 20deg. B. " " " " " 2.58 " 22deg. B. " " " " "
For 1 pound of caustic soda--
1.93 lbs. 50deg. B. sulphuric acid are required. 1.54 " 60deg. B. " " " " 1.28 " 66deg. B. " " " "
It is, of course, feasible to neutralize the spent lye without first determining the causticity by titrating a sample and this is often the case. The operator under such conditions first adds the sulfate of alumina, then the acid, using litmus paper as his indicator. Comparatively, this method of treatment is much slower and not as positive, as the amount of acid or alkali to be added is at all times uncertain, for in the foaming of the lyes their action on litmus is misleading.
After the lye has been filtered to the filtered lye tank it is fed to the evaporator, the method of operation of which varies somewhat with different styles or makes. When it first enters the evaporator the lye is about 11deg.-12deg. B. After boiling the density will gradually rise to 27deg. B. and remain at this gravity for some time and during which time most of the salt is dropped out in the salt filter. As the lye concentrates the gravity gradually rises to 28deg.-30deg. B., which is half crude glycerine and contains about 60 per cent. glycerine. Some operators carry the evaporation to this point and accumulate a quantity of half crude before going on to crude. After half crude is obtained the temperature on the evaporator increases, the vacuum increases and the pressure on the condensation drain goes up (using the same amount of live steam). As the liquor grows heavier the amount of evaporation is less, and less steam is required necessitating the regulation of the steam pressure on the drum. When a temperature of 210deg. F. on the evaporator, with 26 or more inches vacuum on the pump is arrived at, the crude stage has been reached and the liquor now contains about 80 per cent. glycerine in which shape it is usually sold by soap manufacturers. A greater concentration requires more intricate apparatus. After settling a day in the crude tank it is drummed.
Crude glycerine (about 80 per cent. glycerol) free from salt is 33deg. B., or has a specific gravity of 1.3. A sample boiled in an open dish boils at a temperature of 155deg. C. or over.
TWITCHELL PROCESS.
The Twitchell process of saponification consists of causing an almost complete cleavage of fats and oils by the use of the Twitchell reagent or saponifier, a sulfo-aromatic compound. This is made by the action of concentrated sulfuric acid upon a solution of oleic acid or stearic acid in an aromatic hydrocarbon. From 0.5 per cent. to 3 per cent. of the reagent is added and saponification takes place from 12-48 hours by heating in a current of live steam. The reaction is usually accelerated by the presence of a few per cent. of free fatty acids as a starter. Recently the Twitchell double reagent has been introduced through which it is claimed that better colored fatty acids are obtained and the glycerine is free from ash.
The advantages claimed for the Twitchell process as outlined by Joslin[12] are as follows:
1. All the glycerine is separated from the stock before entering the kettle, preventing loss of glycerine in the soap and removing glycerine from spent lye.
2. The liquors contain 15-20 per cent. glycerine whereas spent lyes contain but 3-5 per cent. necessitating less evaporation and consequently being more economical in steam, labor and time.
3. No salt is obtained in the liquors which makes the evaporation cheaper and removes the cause of corrosion of the evaporator; also saves the glycerine retained by the salt.
4. The glycerine liquors are purer and thus the treatment of the lyes is cheaper and simpler and the evaporation less difficult.
5. The glycerine can readily be evaporated to 90 per cent. crude rather than 80 per cent. crude, thus saving drums, labor in handling and freight. The glycerine furthermore receives a higher rating and price, being known as saponification crude which develops no glycols in refining it.
6. The fatty acids obtained by the Twitchell saponifier may be converted into soap by carbonates, thus saving cost in alkali.
7. There is a decrease in the odor of many strong smelling stocks.
8. The glycerine may be obtained from half boiled and cold made soaps as well as soft (potash) soaps.
While the advantages thus outlined are of decided value in the employment of the Twitchell process, the one great disadvantage is that the fatty acids obtained are rather dark in color and are not satisfactorily employed for the making of a soap where whiteness of color is desired.
To carry out the process the previously heated oil or fat to be saponified is run into a lead lined tank. As greases and tallow often contain impurities a preliminary treatment with sulfuric acid is necessary. For a grease 1.25 per cent. of half water and half 66deg. B. sulfuric acid is the approximate amount. The undiluted 66deg. B. acid should never be added directly, as the grease would be charred by this. The grease should be agitated by steam after the required percentage of acid, calculated on the weight of the grease, has been added. The wash lye coming off should be 7deg.-10deg. B. on a good clean grease or 15deg.-22deg. B. on cotton oil or a poor grease. As has been stated the grease is heated before the acid is added or the condensation of the steam necessitates the addition of more acid. After having boiled for 1-2 hours the grease is allowed to settle for 12 hours and run off through a swivel pipe.
After the grease has been washed, as just explained, and settled, it is pumped into a covered wooden tank containing an open brass coil. Some of the second lye from a previous run is usually left in this tank and the grease pumped into this. The amount of this lye should be about one-third to one-half the weight of the grease so that there is about 60 per cent. by weight of grease in the tank after 24 hours boiling. Where occasions arise when there is no second lye about 50 per cent. by weight of distilled water to the amount of grease is run into the tank to replace the lye. The saponifier is then added through a glass or granite ware funnel after the contents of the tank have been brought to a boil. If the boiling is to be continued 48 hours, 1 per cent. of saponifier is added. For 24 hours boiling add 1.5 per cent. The boiling is continued for 24-48 hours allowing 18 inches for boiling room or the grease will boil over.
After boiling has continued the required length of time the mass is settled and the glycerine water is drawn off to the treatment tank. Should a permanent emulsion have formed, due to adding too great an amount of saponifier, a little sulfuric acid (0.1 per cent.-0.3 per cent.) will readily break this. During the time this is being done the space between the grease and the cover on the tank is kept filled with steam as contact with the air darkens the fatty acids.
To the grease remaining in the tank distilled water (condensed water from steam coils) to one-half its volume is added and the boiling continued 12-24 hours. The grease is then settled and the clear grease run off through a swivel pipe. A layer of emulsion usually forms between the clear grease and lye so that it may easily be determined when the grease has all been run off. To prevent discoloration of the fatty acids it is necessary to neutralize the lye with barium carbonate. The amount of this to be added depends upon the percentage of saponifier used. About 1/10 the weight of saponifier is the right amount. The barium carbonate is added through the funnel at the top of the tank mixed with a little water and the lye tested until it is neutral to methyl orange indicator. When the fatty acids are thus treated they will not darken upon exposure to the air when run off.
Fresh grease is now pumped into the lye or water remaining in the tank and the process repeated.
The glycerine water or first lye is run to the treatment tank, the fat skimmed off and neutralized with lime until it shows pink with phenolphthalein, after having been thoroughly boiled with steam. About 0.25 per cent. lime is the proper amount to add. The mixture is then allowed to settle and the supernatant mixture drawn off and run to the glycerine evaporator feed tank. The lime which holds considerable glycerine is filtered and the liquor added to the other. The evaporation is carried out in two stages. The glycerine water is first evaporated to about 60 per cent. glycerol, then dropped into a settling tank to settle out the calcium sulfate. The clear liquor is then evaporated to crude (about 90 per cent. glycerine) and the sediment filtered and also evaporated to crude.
As to the amount of saponifier to use on various stocks, this is best determined by experiment as to how high a percentage gives dark colored fatty acids. For good stock such as clean tallow, prime cottonseed oil, corn oil, cocoanut oil and stock of this kind 0.75 per cent. saponifier is sufficient. For poorer grades of tallow, house grease, poor cottonseed oil, etc., 1 per cent. saponifier is required and for poorer grade greases higher percentages. The percentage of fatty acids developed varies in various stocks, and also varies with the care that the operation is carried out, but is usually between 85 per cent.-95 per cent. Due to the water taken up in the saponification process there is a yield of about 103 pounds of fatty acids and glycerine for 100 pounds of fat.
The Twitchell reagent has undoubtedly caused a decided advance in the saponification of fats and oils and has been of great value to the soap manufacturer, because with a small expenditure it is possible to compete with the much more expensive equipment necessary for autoclave saponification. The drawback, however, has been that the reagent imparted a dark color to the fatty acids obtained, due to decomposition products forming when the reagent is made, and hence is not suitable for use in soaps where whiteness of color is desired.
There have recently been two new reagents introduced which act as catalyzers in splitting fats, just as the Twitchell reagent acts, but the fatty acids produced by the cleavage are of good color. The saponification, furthermore, takes place more rapidly. These are the Pfeilring reagent and Kontact reagent.
The Pfeilring reagent is very similar to the Twitchell reagent, being made from hydrogenated castor oil and naphthalene by sulfonation with concentrated sulfuric acid. It is manufactured in Germany and is being extensively used in that country with good success.
The Kontact or Petroff reagent, discovered by Petroff in Russia, is made from sulfonated mineral oils. Until very recently it has only been manufactured in Europe, but now that it has been found possible to obtain the proper mineral constituent from American petroleum, it is being manufactured in this country, and it is very probable that it will replace the Twitchell reagent because of the advantages derived by using it, as compared to the old Twitchell reagent.
The method and equipment necessary for employing either the Pfeilring or Kontact reagents is exactly the same as in using the Twitchell process.
AUTOCLAVE SAPONIFICATION.
While the introduction of the Twitchell process to a great extent replaced the autoclave method of saponification for obtaining fatty acids for soap making, the autoclave method is also used. This process consists in heating the previously purified fat or oil in the presence of lime and water, or water only, for several hours, which causes a splitting of the glycerides into fatty acids and glycerine. The advantage of autoclave saponification over the Twitchell process is that a greater cleavage of the fats and oils results in less time and at a slightly less expense. The glycerine thus obtained is also purer and of better color than that obtained by Twitchelling the fats.
An autoclave or digestor consists of a strongly constructed, closed cylindrical tank, usually made of copper, and is so built as to resist internal pressure. The digestor is usually 3 to 5 feet in diameter and from 18 to 25 feet high. It may be set up horizontally or vertically and is covered with an asbestos jacket to retain the heat. Various inlets and outlets for the fats, steam, etc., as well as a pressure gauge and safety valve are also a necessary part of the equipment.
LIME SAPONIFICATION.
The saponification in an autoclave is usually carried out by introducing the fats into the autoclave with a percentage of lime, magnesia or zinc oxide, together with water. If the fats contain any great amount of impurities, it is first necessary to purify them either by a treatment with weak sulfuric acid, as described under the Twitchell process, or by boiling them up with brine and settling out the impurities from the hot fat.
To charge the autoclave a partial vacuum is created therein by condensation of steam just before running the purified oil in from an elevated tank. The required quantity of unslaked lime, 2 to 4 per cent. of the weight of the fat, is run in with the molten fat, together with 30 per cent. to 50 per cent. of water. While 8.7 per cent. lime is theoretically required, practice has shown that 2 per cent. to 4 per cent. is sufficient. The digestor, having been charged and adjusted, steam is turned on and a pressure of 8 to 10 atmospheres maintained thereon for a period of six to ten hours. Samples of the fat are taken at various intervals and the percentage of free fatty acids determined. When the saponification is completed the contents of the autoclave are removed, usually by blowing out the digestor into a wooden settling tank, or by first running off the glycerine water and then blowing out the lime, soap and fatty acids. The mass discharged from the digestor separates into two layers, the upper consisting of a mixture of lime soap or "rock" and fatty acids, and the lower layer contains the glycerine or "sweet" water. The glycerine water is first run off through a clearing tank or oil separator, if this has not been done directly from the autoclave, and the mass remaining washed once or twice more with water to remove any glycerine still retained by the lime soap. The calculated amount of sulfuric acid to decompose the lime "rock" is then added, and the mass agitated until the fatty acids contained therein are entirely set free. Another small wash is then given and the wash water added to the glycerine water already run off. The glycerine water is neutralized with lime, filtered and concentrated as in the Twitchell process.
Due to the difficulties of working the autoclave saponification with lime, decomposing the large amount of lime soap obtained and dealing with much gypsum formed thereby which collects as a sediment and necessitates cleaning the tanks, other substances are used to replace lime. Magnesia, about 2 per cent. of the weight of the fat, is used and gives better results than lime. One-half to 1 per cent. of zinc oxide of the weight of the fat is even better adapted and is now being extensively employed for this purpose. In using zinc oxide it is possible to recover the zinc salts and use them over again in the digestor, which makes the process as cheap to work as with lime, with far more satisfactory results.
ACID SAPONIFICATION.
While it is possible to saponify fats and oils in an autoclave with the addition of acid to the fat, unless a specially-constructed digestor is built, the action of the acid on the metal from which the autoclave is constructed prohibits its use. The acid saponification is therefore carried out by another method.
The method of procedure for acid saponification, therefore, is to first purify the fats with dilute acid as already described. The purified, hot or warm, dry fat is then run to a specially-built acidifier or a lead-lined tank and from 4 per cent. to 6 per cent. of concentrated sulfuric acid added to the fat, depending upon its character, the degree of saponification required, temperature and time of saponification. A temperature of 110 degrees C. is maintained and the mass mixed from four to six hours. The tank is then allowed to settle out the tar formed during the saponification, and the fatty acids run off to another tank and boiled up about three times with one-third the amount of water. The water thus obtained contains the glycerine, and after neutralization is concentrated.
AQUEOUS SAPONIFICATION.
While lime or a similar substance is ordinarily used to aid in splitting fats in an autoclave, the old water process is still used. This is a convenient, though slower and more dangerous method, of producing the hydrolysis of the glyceride, as well as the simplest in that fatty acids and glycerine in a water solution are obtained. The method consists in merely charging the autoclave with fats and adding about 30 per cent. to 40 per cent. of their weight of water, depending on the amount of free fatty acid and subjecting the charge to a pressure of 150 to 300 pounds, until the splitting has taken place. This is a much higher pressure than when lime is used and therefore a very strong autoclave is required. Since fatty acids and pure glycerine water are obtained no subsequent treatment of the finished charge is necessary except separating the glycerine water and giving the fatty acids a wash with water to remove all the glycerine from them.
SPLITTING FATS WITH FERMENTS.
In discussing the causes of rancidity of oils and fats it was pointed out that the initial splitting of these is due to enzymes, organized ferments. In the seeds of the castor oil plant, especially in the protoplasm of the seed, the enzyme which has the property of causing hydrolysis of the glycerides is found. The ferment from the seeds of the castor oil plant is now extracted and used upon a commercial basis for splitting fats.
The equipment necessary to carry out this method of saponification is a round, iron, lead-lined tank with a conical bottom, preferably about twice as long as it is wide. Open and closed steam coils are also necessary in the tank.
The oils are first heated and run into this tank. The right temperature to heat these to is about 1 degree to 2 degrees above their solidification point. For liquid oils 23 degrees C. is the proper heat as under 20 degrees C. the cleavage takes place slowly. Fats titering 44 degrees C. or above must be brought down in titer by mixing with them oils of a lower titer as the ferment or enzyme is killed at about 45 degrees C. and thus loses its power of splitting. It is also necessary to have the fat in the liquid state or the ferment does not act. The proper temperature must be maintained with dry steam.
It is, of course, necessary to add water, which may be any kind desired, condensed, water from steam coils, well, city, etc. From 30 per cent. to 40 per cent., on the average 35 per cent. of water is added, as the amount necessary is regulated so as to not dilute the glycerine water unnecessarily. To increase the hydrolysis a catalyzer, some neutral salt, usually manganese sulfate is added in the proportion of 0.15 per cent. appears to vary directly as the saponification number of the fat or oil. The approximate percentages of fermentive substance to be added to various oils and fats follow:
Cocoanut oil 8 % Palm Kernel oil 8 % Cottonseed oil 6-7 % Linseed oil 4-5 % Tallow oil 8-10%
The oil, water, manganese sulfate and ferment having been placed in the tank in the order named, the mixture is agitated with air for about a quarter of an hour to form an even emulsion, in which state the mass is kept by stirring occasionally with air while the saponification is taking place. A temperature is maintained a degree or two above the titer point of the fat with closed steam which may be aided by covering the tank for a period of 24 to 48 hours. The splitting takes place rapidly at first, then proceeds more slowly. In 24 hours 80 per cent. of the fats are split and in 48 hours 85 per cent. to 90 per cent.
When the cleavage has reached the desired point the mass is heated to 80 degrees-85 degrees C. with live or indirect steam while stirring with air. Then 0.1 per cent.-0.15 per cent of concentrated sulfuric acid diluted with water is added to break the emulsion. When the emulsion is broken the glycerine water is allowed to settle out and drawn off. The glycerine water contains 12 per cent. to 25 per cent. glycerine and contains manganese sulfate, sulfuric acid and albuminous matter. Through neutralization with lime at boiling temperature and filtration the impurities can almost all be removed after which the glycerine water may be fed to the evaporator. Should it be desired to overcome the trouble due to the gypsum formed in the glycerine, the lime treatment may be combined with a previous treatment of the glycerine water with barium hydrate to remove the sulfuric acid, then later oxalic acid to precipitate the lime.
The fatty acids obtained by splitting with ferments are of very good color and adaptable for soap making.
KREBITZ PROCESS.
The Krebitz process which has been used to some extent in Europe is based upon the conversion of the fat or oil into lime soap which is transformed into the soda soap by the addition of sodium carbonate. To carry out the process a convenient batch of, say, 10,000 pounds of fat or oil, is run into a shallow kettle containing 1,200 to 1,400 pounds of lime previously slaked with 3,700 to 4,500 pounds of water. The mass is slowly heated with live steam to almost boiling until an emulsion is obtained. The tank is then covered and allowed to stand about 12 hours. The lime soap thus formed is dropped from the tank into the hopper of a mill, finely ground and conveyed to a leeching tank. The glycerine is washed out and the glycerine water run to a tank for evaporation. The soap is then further washed and these washings are run to other tanks to be used over again to wash a fresh batch of soap. About 150,000 pounds of water will wash the soap made from 10,000 pounds of fat which makes between 15,000 and 16,000 pounds of soap. The first wash contains approximately 10 per cent. glycerine and under ordinary circumstances this only need be evaporated for glycerine recovery.
After extracting the glycerine the soap is slowly introduced into a boiling solution of sodium carbonate or soda ash and boiled until the soda has replaced the lime. This is indicated by the disappearance of the small lumps of lime soap. Caustic soda is then added to saponify the fat not converted by the lime saponification. The soap is then salted out and allowed to settle out the calcium carbonate. This drops to the bottom of the kettle as a heavy sludge entangling about 10 per cent. of the soap. A portion of this soap may be recovered by agitating the sludge with heat and water, pumping the soap off the top and filtering the remaining sludge.
While the soap thus obtained is very good, the percentage of glycerine recovered is greatly increased and the cost of alkali as carbonate is less. The disadvantages are many. Large quantities of lime are required; it is difficult to recover the soap from the lime sludge; the operations are numerous prior to the soap making proper and rather complicated apparatus is required.
DISTILLATION OF FATTY ACIDS.
The fatty acids obtained by various methods of saponification may be further improved by distillation.
In order to carry out this distillation, two methods may be pursued, first, the continuous method, whereby the fatty acids are continually distilled for five to six days, and, second, the two phase method, whereby the distillation continues for 16 to 20 hours, after which the residue is drawn off, treated with acid, and its distillate added to a fresh charge of fatty acids. The latter method is by far the best, since the advantages derived by thus proceeding more than compensate the necessity of cleaning the still. Better colored fatty acids are obtained; less unsaponifiable matter is contained therein; there is no accumulation of impurities; the amount of neutral fat is lessened because the treatment of the tar with acid causes a cleavage of the neutral fat and the candle tar or pitch obtained is harder and better and thus more valuable.
The stills are usually built of copper, which are heated by both direct fire and superheated steam. Distillation under vacuum is advisable. To begin the distilling operation, the still is first filled with dry hot fatty acids to the proper level. Superheated steam is then admitted and the condenser is first heated to prevent the freezing of the fatty acids, passing over into same. When the temperature reaches 230 deg. C. the distillation begins. At the beginning, the fatty acids flow from the condenser, an intense green color, due to the formation of copper soaps produced by the action of the fatty acids on the copper still. This color may easily be removed by treating with dilute acid to decompose the copper soaps.
In vacuum distillation, the operation is begun without the use of vacuum. Vacuum is introduced only when the distillation has proceeded for a time and the introduction of this must be carefully regulated, else the rapid influence of vacuum will cause the contents of the still to overflow. When distillation has begun a constant level of fatty acids is retained therein by opening the feeding valve to same, and the heat is so regulated as to produce the desired rate of distillation. As soon as the distillate flows darker and slower, the feeding valve to the still is shut off and the distillation continued until most of the contents of the still are distilled off, which is indicated by a rise in the temperature. Distillation is then discontinued, the still shut down, and in about an hour the contents are sufficiently cool to be emptied. The residue is run off into a proper receiving vessel, treated with dilute acid and used in the distillation of tar.
In the distillation of tar the same method as the above is followed, only distillation proceeds at a higher temperature. The first portion and last portion of the distillate from tar are so dark that it is necessary to add them to a fresh charge of fatty acids. By a well conducted distillation of tar about 50 per cent. of the fatty acids from the tar can be used to mix with the distilled fatty acids. The residue of this operation called stearine pitch or candle tar consists of a hard, brittle, dark substance. Elastic pitch only results where distillation has been kept constant for several days without interrupting the process, and re-distilling the tar. In a good distillation the distillation loss is 0.5 to 1.5% and loss in pitch 1.5%. Fatty acids which are not acidified deliver about 3% of pitch. Very impure fats yield even a higher percentage in spite of acidifying. For a long time it was found impossible to find any use for stearine pitch, but in recent years a use has been found for same in the electrical installation of cables.
FOOTNOTES:
[12] Journ. Ind. Eng. Chem. (1909), I, p. 654.
## CHAPTER VI
Analytical Methods.
While it is possible to attain a certain amount of efficiency in determining the worth of the raw material entering into the manufacture of soap through organoleptic methods, these are by no means accurate. It is, therefore, necessary to revert to chemical methods to correctly determine the selection of fats, oil or other substances used in soap making, as well as standardizing a particular soap manufactured and to properly regulate the glycerine recovered.
It is not our purpose to cover in detail the numerous analytical processes which may be employed in the examination of fats and oils, alkalis, soap and glycerine, as these are fully and accurately covered in various texts, but rather to give briefly the necessary tests which ought to be carried out in factories where large amounts of soap are made. Occasion often arises where it is impossible to employ a chemist, yet it is possible to have this work done by a competent person or to have someone instruct himself as just how to carry out the more simple analyses, which is not a very difficult matter. The various standard solutions necessary to carrying out the simpler titrations can readily be purchased from dealers in chemical apparatus and it does not take extraordinary intelligence for anyone to operate a burette, yet in many soap plants in this country absolutely no attention is paid to the examining of raw material, though many thousand pounds are handled annually, which, if they were more carefully examined would result in the saving of much more money than it costs to examine them or have them at least occasionally analyzed.
ANALYSIS OF FATS AND OILS.
In order to arrive at proper results in the analysis of a fat or oil, it is necessary to have a proper sample. To obtain this a sample of several of the packages of oil or fat is taken and these mixed or molten together into a composite sample which is used in making the tests. If the oil or fat is solid, a tester is used in taking the sample from the package and if they are liquid, it is a simple matter to draw off a uniform sample from each package and from these to form a composite sample.
In purchasing an oil or fat for soap making, the manufacturer is usually interested in the amount of free fatty acid contained therein, of moisture, the titer, the percentage of unsaponifiable matter and to previously determine the color of soap which will be obtained where color is an object.
DETERMINATION OF FREE FATTY ACIDS.
Since the free fatty acid content of a fat or oil represents a loss of glycerine, the greater the percentage of free fatty acid, the less glycerine is contained in the fat or oil, it is advisable to purchase a fat or oil with the lower free acid, other properties and the price being the same.
While the mean molecular weight of the mixed free fatty acids varies with the same and different oils or fats and should be determined for any particular analysis for accuracy, the free fatty acid is usually expressed as oleic acid, which has a molecular weight of 282.
To carry out the analysis 5 to 20 grams of the fat are weighed out into an Erlenmeyer flask and 50 cubic centimeters of carefully neutralized alcohol are added. In order to neutralize the alcohol add a few drops of phenolphthalein solution to same and add a weak caustic soda solution drop by drop until a very faint pink color is obtained upon shaking or stirring the alcohol thoroughly. The mixture of fat and neutralized alcohol is then heated to boiling and titrated with tenth normal alkali solution, using phenolphthalein as an indicator. As only the free fatty acids are readily soluble in the alcohol and the fat itself only slightly mixes with it, the flask should be well agitated toward the end of the titration. When a faint pink color remains after thoroughly agitating the flask the end point is reached. In order to calculate the percentage of free fatty acid as oleic acid, multiply the number of cubic centimeters of tenth normal alkali used as read on the burette by 0.0282 and divide by the number of grams of fat taken for the determination and multiply by 100.
When dark colored oils or fats are being titrated it is often difficult to obtain a good end point with phenolphthalein. In such cases about 2 cubic centimeters of a 2 per cent. alcoholic solution of Alkali Blue 6 B is recommended.
Another method of directly determining the free fatty acid content of tallow or grease upon which this determination is most often made is to weigh out into an Erlenmeyer flask exactly 5.645 grams of a sample of tallow or grease. Add about 75 cubic centimeters of neutralized alcohol. Heat until it boils, then titrate with tenth normal alkali and divide the reading by 2, which gives the percentage of free fatty acid as oleic. If a fifth normal caustic solution is used, the reading on the burette gives the percentage of free fatty acid directly. This method, while it eliminates the necessity of calculation, is troublesome in that it is difficult to obtain the exact weight of fat.
MOISTURE.
To calculate the amount of moisture contained in a fat or oil 5 to 10 grams are weighed into a flat bottom dish, together with a known amount of clean, dry sand, if it is so desired. The dish is then heated over a water bath, or at a temperature of 100-110 degs. C., until it no longer loses weight upon drying and reweighing the dish. One hour should elapse between the time the dish is put on the water bath and the time it is taken off to reweigh. The difference between the weight of the dish is put on the water bath and the time it is taken off when it reaches a constant weight is moisture. This difference divided by the original weight of the fat or oil x 100 gives the percentage of moisture.
When highly unsaturated fats or oils are being analyzed for moisture, an error may be introduced either by the absorption of oxygen, which is accelerated at higher temperature, or by the formation of volatile fatty acids. The former causes an increase in weight, the latter causes a decrease. To obviate this, the above operation of drying should be carried out in the presence of some inert gas like hydrogen, carbon dioxide, or nitrogen.
TITER.
The titer of a fat or oil is really an indication of the amount of stearic acid contained therein. The titer, expressed in degrees Centigrade, is the solidification point of the fatty acids of an oil or fat. In order to carry out the operation a Centigrade thermometer graduated in one or two-tenths of a degree is necessary. A thermometer graduated between 10 degs. centigrade to 60 degs. centigrade is best adapted and the graduations should be clear cut and distinct.
To make the determination about 30 grams of fat are roughly weighed in a metal dish and 30-40 cubic centimeters of a 30 per cent. (36 degs. Baume) solution of sodium hydroxide, together with 30-40 cubic centimeters of alcohol, denatured alcohol will do, are added and the mass heated until saponified. Heat over a low flame or over an asbestos plate until the soap thus formed is dry, constantly stirring the contents of the dish to prevent burning. The dried soap is then dissolved in about 1000 cubic centimeters of water, being certain that all the alcohol has been expelled by boiling the soap solution for about half an hour. When the soap is in solution add sufficient sulphuric acid to decompose the soap, approximately 100 cubic centimeters of 25 degs. Baume sulphuric acid, and boil until the fatty acids form a clear layer on top of the liquid. A few pieces of pumice stone put into the mixture will prevent the bumping caused by boiling. Siphon off the water from the bottom of the dish and wash the fatty acids with boiling water until free from sulphuric acid. Collect the fatty acids in a small casserole or beaker and dry them over a steam bath or drying oven at 110 degs. Centigrade. When the fatty acids are dry, cool them to about 10 degs. above the titer expected and transfer them to a titer tube or short test tube which is firmly supported by a cork in the opening of a salt mouth bottle. Hang the thermometer by a cord from above the supported tube so it reaches close to the bottom when in the titer tube containing the fatty acids and so that it may be used as a stirrer. Stir the mass rather slowly, closely noting the temperature. The temperature will gradually fall during the stirring operation and finally remain stationary for half a minute or so then rise from 0.1 to 0.5 degs. The highest point to which the mercury rises after having been stationary is taken as the reading of the titer.
DETERMINATION OF UNSAPONIFIABLE MATTER.
In order to determine the unsaponifiable matter in fats and oils they are first saponified, then the unsaponifiable, which consists mainly of hydrocarbons and the higher alcohols cholesterol or phytosterol, is extracted with ether or petroleum ether, the ether evaporated and the residue weighed as unsaponifiable.
To carry out the process first saponify about 5 grams of fat or oil with an excess of alcoholic potassium hydrate, 20-30 cubic centimeters of a 1 to 10 solution of potassium hydroxide in alcohol until the alcohol is evaporated over a steam bath. Wash the soap thus formed into a separatory funnel of 200 cubic centimeters capacity with 80-100 cubic centimeters water. Then add about 60 cubic centimeters of ether, petroleum ether or 86 degs. gasoline and thoroughly shake the funnel to extract the unsaponifiable. Should the two layers not separate readily, add a few cubic centimeters of alcohol, which will readily cause them to separate. Draw off the watery solution from beneath and wash the ether with water containing a few drops of sodium hydrate and run to another dish. Pour the watery solution into the funnel again and repeat the extraction once or twice more or until the ether shows no discoloration. Combine the ether extractions into the funnel and wash with water until no alkaline reaction is obtained from the wash water. Run the ether extract to a weighed dish, evaporate and dry rapidly in a drying oven. As some of the hydrocarbons are readily volatile at 100 degs. Centigrade, the drying should not be carried on any longer than necessary. The residue is then weighed and the original weight of fat taken divided into the weight of the residue x 100 gives the percentage unsaponifiable.
TEST FOR COLOR OF SOAP.
It is often desirable to determine the color of the finished soap by a rapid determination before it is made into soap. It often happens, especially with the tallows, that a dark colored sample produces a light colored soap, whereas a bleached light colored tallow produces a soap off shade.
To rapidly determine whether the color easily washes out of the tallow with lye, 100 cubic centimeters of tallow are saponified in an enameled or iron dish with 100 cubic centimeters of 21 degs. Baume soda lye and 100 cubic centimeters of denatured alcohol. Continue heating over a wire gauze until all the alcohol is expelled and then add 50 cubic centimeters of the 21 degs. Baume lye to grain the soap. Allow the lyes to settle and with an inverted pipette draw off the lyes into a test tube or bottle. Close the soap with 100 cubic centimeters of hot water and when closed again grain with 50 cubic centimeters of the lye by just bringing to a boil over an open flame. Again allow the lyes to settle and put aside a sample of the lye for comparison. Repeat the process of closing, graining and settling and take a sample of lye. If the lye is still discolored repeat the above operations again or until the lye is colorless. Ordinarily all the color will come out with the third lye. The soap thus obtained contains considerable water which makes it appear white. The soap is, therefore, dried to about 15 per cent. moisture and examined for color. The color thus obtained is a very good criterion as to what may be expected in the soap kettle.
By making the above analyses of fats or oils the main properties as to their adaptability for being made into soap are determined. In some cases, especially where adulteration or mixtures of oils are suspected, it is necessary to further analyze same. The methods of carrying out these analyses are fully covered by various texts on fats and oils and we will not go into details regarding the method of procedure in carrying these out.
TESTING OF ALKALIS USED IN SOAP MAKING.
The alkalis entering into the manufacture of soap such as caustic soda or sodium hydroxide, caustic potash or potassium hydrate, carbonate of soda or sodium carbonate, carbonate of potash or potassium carbonate usually contain impurities which do not enter into combination with the fats or fatty acids to form soap. It is out of the question to use chemically pure alkalis in soap making, hence it is often necessary to determine the alkalinity of an alkali. It may again be pointed out that in saponifying a neutral fat or oil only caustic soda or potash are efficient and the carbonate contained in these only combines to a more or less extent with any free fatty acids contained in the oils or fats. Caustic soda or potash or lyes made from these alkalis upon exposure to the air are gradually converted into sodium or potassium carbonate by the action of the carbon dioxide contained in the air. While the amount of carbonate thus formed is not very great and is greatest upon the surface, all lyes as well as caustic alkalis contain some carbonate. This carbonate introduces an error in the analysis of caustic alkalis when accuracy is required and thus in the analysis of caustic soda or potash it is necessary to remove the carbonate when the true alkalinity as sodium hydroxide or potassium hydroxide is desired. This may be done by titration in alcohol which has been neutralized.
In order to determine the alkalinity of any of the above mentioned alkalis, it is first necessary to obtain a representative sample of the substance to be analyzed. To do this take small samples from various portions of the package and combine them into a composite sample. Caustic potash and soda are hygroscopic and samples should be weighed at once or kept in a well stoppered bottle. Sodium or potassium carbonate can be weighed more easily as they do not rapidly absorb moisture from the air.
To weigh the caustic soda or potash place about five grams on a watch glass on a balance and weigh as rapidly as possible. Wash into a 500 cubic centimeter volumetric flask and bring to the mark with distilled water. Pipette off 50 cubic centimeters into a 200 cubic centimeter beaker, dilute slightly with distilled water, add a few drops of methyl orange indicator and titrate with normal acid. For the carbonates about 1 gram may be weighed, washed into a 400 cubic centimeter beaker, diluted with distilled water, methyl orange indicator added and titrated with normal acid. It is advisable to use methyl orange indicator in these titrations as phenolphthalein is affected by the carbon dioxide generated when an acid reacts with a carbonate and does not give the proper end point, unless the solution is boiled to expel the carbon dioxide. Litmus may also be used as the indicator, but here again it is necessary to boil as carbon dioxide also affects this substance. As an aid to the action of these common indicators the following table may be helpful:
_Color in _Color in _Indicator._ Acid Alkaline _Action of Solution._ Solution._ CO_{2}._
Methyl orange Red Yellow Very slightly acid Phenolphthalein Colorless Red Acid Litmus Red Blue Acid
It may be further stated that methyl orange at the neutral point is orange in color.
To calculate the percentage of effective alkali from the above titrations, it must be first pointed out that in the case of caustic potash or soda aliquot portions are taken. This is done to reduce the error necessarily involved by weighing, as the absorption of water is decided. Thus we had, say, exactly 5 grams which weighed 5.05 grams by the time it was balanced. This was dissolved in 500 cubic centimeters of water and 50 cubic centimeters or one tenth of the amount of the solution was taken, or in each 50 cubic centimeters there were 0.505 grams of the sample. We thus reduced the error of weighing by one tenth provided other conditions introduce no error. In the case of the carbonates the weight is taken directly.
One cubic centimeter of a normal acid solution is the equivalent of:
Grams. Sodium Carbonate, Na_{2}CO_{3} 0.05305 Sodium Hydroxide, NaOH 0.04006 Sodium Oxide, Na_{2}O 0.02905 Carbonate K_{2}CO_{3} 0.06908 Potassium Hydroxide, KOH 0.05616 Potassium Oxide, K_{2}O 0.04715
Hence to arrive at the alkalinity we multiply the number of cubic centimeters, read on the burette, by the factor opposite the terms in which we desire to express the alkalinity, divide the weight in grams thus obtained by the original weight taken, and multiply the result by 100, which gives the percentage of alkali in the proper terms. For example, say, we took the 0.505 grams of caustic potash as explained above and required 8.7 cubic centimeter normal acid to neutralize the solution, then
8.7 x .05616 = .4886 grams KOH in sample
.4886 ----- x 100 = 96.73% KOH in sample. .505
Caustic potash often contains some caustic soda, and while it is possible to express the results in terms of KOH, regardless of any trouble that may be caused by this mixture in soap making, an error is introduced in the results, not all the alkali being caustic potash. In such cases it is advisable to consult a book on analysis as the analysis is far more complicated than those given we will not consider it. The presence of carbonates, as already stated, also causes an error. To overcome this the alkali is titrated in absolute alcohol, filtering off the insoluble carbonate. The soluble portion is caustic hydrate and may be titrated as such. The carbonate remaining on the filter paper is dissolved in water and titrated as carbonate.
SOAP ANALYSIS.
To obtain a sample of a cake of soap for analysis is a rather difficult matter as the moisture content of the outer and inner layer varies considerably. To overcome this difficulty a borer or sampler may be run right through the cake of soap, or slices may be cut from various parts of the cake, or the cake may be cut and run through a meat chopper several times and mixed. A sufficient amount of a homogeneous sample obtained by any of these methods is preserved for the entire analysis by keeping the soap in a securely stoppered bottle.
The more important determinations of soap are moisture, free alkali, or fatty acid, combined alkali and total fatty matter. Besides these it is often necessary to determine insoluble matter, glycerine, unsaponifiable matter, rosin and sugar.
MOISTURE.
The analysis of soap for moisture, at its best, is most unsatisfactory, for by heating it is impossible to drive off all the water, and on the other hand volatile oils driven off by heat are a part of the loss represented as moisture.
The usual method of determining moisture is to weigh 2 to 3 grams of finely shaved soap on a watch glass and heat in an oven at 105 degrees C. for 2 to 3 hours. The loss in weight is represented as water, although it is really impossible to drive off all the water in this way.
To overcome the difficulties just mentioned either the Smith or Fahrion method may be used. Allen recommends Smith's method which is said to be truthful to within 0.25 per cent. Fahrion's method, according to the author, gives reliable results to within 0.5 per cent. Both are more rapid than the above manipulation. To carry out the method of Smith, 5 to 10 grams of finely ground soap are heated over a sand bath with a small Bunsen flame beneath it, in a large porcelain crucible. The heating takes 20 to 30 minutes, or until no further evidence is present of water being driven off. This may be tested by the fogging of a cold piece of glass held over the crucible immediately upon removing the burner. When no fog appears the soap is considered dry. Any lumps of soap may be broken up by a small glass rod, weighed with the crucible, and with a roughened end to more easily separate the lumps. Should the soap burn, this can readily be detected by the odor, which, of course, renders the analysis useless. The loss in weight is moisture.
By Fahrion's method[13], 2 to 4 grams of soap are weighed in a platinum crucible and about three times its weight of oleic acid, which has been heated at 120 degrees C. until all the water is driven off and preserved from moisture, is added and reweighed. The dish is then cautiously heated with a small flame until all the water is driven off and all the soap is dissolved. Care must be exercised not to heat too highly or the oleic acid will decompose. The moment the water is all driven off a clear solution is formed, provided no fillers are present in the soap. The dish is then cooled in a dessicator and reweighed. The loss in weight of acid plus soap is moisture and is calculated on the weight of soap taken. This determination takes about fifteen minutes.
FREE ALKALI OR ACID.
(_a_) _Alcoholic Method._
Test a freshly cut surface of the soap with a few drops of an alcoholic phenolphthalein solution. If it does not turn red it may be assumed free fat is present; should a red color appear, free alkali is present. In any case dissolve 2 to 5 grams of soap in 100 cubic centimeters of neutralized alcohol and heat to boiling until in solution. Filter off the undissolved portion containing carbonate, etc., and wash with alcohol. Add phenolphthalein to the filtrate and titrate with N/10 acid and calculate the per cent. of free alkali as sodium or potassium hydroxide. Should the filtrate be acid instead of alkaline, titrate with N/10 alkali and calculate the percentage of free fatty acid as oleic acid.
The insoluble portion remaining on the filter paper is washed with water until all the carbonate is dissolved. The washings are then titrated with N/10 sulfuric acid and expressed as sodium or potassium carbonate. Should borates or silicates be present it is possible to express in terms of these. If borax is present the carbon dioxide is boiled off after neutralizing exactly to methyl orange; cool, add mannite and phenolphthalein and titrate the boric acid with standard alkali.
(_b_) _Bosshard and Huggenberg Method._[14]
In using the alcoholic method for the determination of the free alkali or fat in soap there is a possibility of both free fat and free alkali being present. Upon boiling in an alcoholic solution the fat will be saponified, thus introducing an error in the analysis. The method of Bosshard and Huggenberg overcomes this objection. Their method is briefly as follows:
_Reagents._
1. N/10 hydrochloric acid to standardize N/10 alcoholic sodium hydroxide.
2. Approximately N/10 alcoholic sodium hydroxide to fix and control the N/40 stearic acid.
3. N/40 stearic acid. Preparation: About 7.1 grams of stearic acid are dissolved in one liter of absolute alcohol, the solution filtered, the strength determined by titration against N/10 NaOH and then protected in a well stoppered bottle, or better still connected directly to the burette.
4. A 10 per cent. solution of barium chloride. Preparation: 100 grams of barium chloride are dissolved in one liter of distilled water and filtered. The neutrality of the solution should be proven as it must be neutral.
5. [Greek: alpha] naptholphthalein indicator according to Sorenson. Preparation: 0.1 gram of [Greek: alpha] naphtholphthalein is dissolved in 150 cubic centimeters of alcohol and 100 cubic centimeters of water. For every 10 cubic centimeters of liquid use at least 12 drops of indicator.
6. Phenolphthalein solution 1 gram to 100 cubic centimeter 96 per cent. alcohol.
7. Solvent, 50 per cent. alcohol neutralized.
MANIPULATION.
First--Determine the strength of the N/10 alcoholic sodium hydroxide in terms of N/10 hydrochloric acid and calculate the factor, e. g.:
10 c.c. N/10 alcoholic NaOH = 9.95 N/10 HCl} 10 c.c. N/10 alcoholic NaOH = 9.96 N/10 HCl} 9.96
The alcoholic N/10 NaOH has a factor of 0.996.
Second--Control the N/40 stearic acid with the above alkali to obtain its factor, e. g.:
40 c.c. N/40 alcoholic stearic acid = 10.18 c.c. N/10 NaOH } 40 c.c. N/40 alcoholic stearic acid = } 10.2 10.22 c.c. N/10 NaOH }
10.2 x F N/10 NaOH (0.996) = Factor N/40 stearic acid
Therefore Factor N/40 stearic acid = 1.016.
Third--About 5 grams of soap are weighed and dissolved in 100 cubic centimeters of 50 per cent. neutralized alcohol in a 250 cubic centimeter Erlenmeyer flask over a water bath and connected with a reflux condensor. When completely dissolved, which takes but a few moments, it is cooled by allowing a stream of running water to run over the outside of the flask.
Fourth--The soap is precipitated with 15 to 20 cubic centimeters of the 10 per cent. barium chloride solution.
Fifth--After the addition of 2 to 5 cubic centimeters of [Greek: alpha] naphtholphthalein solution the solution is titrated with N/40 alcoholic stearic acid. [Greek: alpha] naphtholphthalein is red with an excess of stearic acid. To mark the color changes it is advisable to first run a few blanks until the eye has become accustomed to the change in the indicator in the same way. The change from green to red can then be carefully observed.
Let us presume 5 grams of soap were taken for the analysis and 20 cubic centimeters of N/40 stearic acid were required for the titration then to calculate the amount of NaOH since the stearic factor is 1.016.
20 x 1.016 = 20.32 N/40 stearic acid really required.
1 cubic centimeter N/40 stearic acid = 0.02 per cent. NaOH for 5 grams soap.
[Greek: Delta] 20.32 cubic centimeters N/40 stearic acid = 0.02 x 20.32 per cent. NaOH for 5 grams soap.
Hence the soap contains 0.4064 per cent. NaOH.
It is necessary, however, to make a correction by this method. When the free alkali amounts to over 0.1 per cent. the correction is + 0.01, and when the free alkali exceeds 0.4 per cent. the correction is + 0.04, hence in the above case we multiply 0.004064 by 0.04, add this amount to 0.004064 and multiply by 100 to obtain the true percentage. Should the alkalinity have been near 0.1 per cent. we would have multiplied by 0.01 and added this.
If carbonate is also present in the soap, another 5 grams of soap is dissolved in 100 cubic centimeters of 50 per cent. alcohol and the solution titrated directly after cooling with N/40 stearic acid, using [Greek: alpha] naphtholphthalein or phenolphthalein as an indicator, without the addition of barium chloride. From the difference of the two titrations the alkali present as carbonate is determined.
If the decomposed soap solution is colorless with phenolphthalein, free fatty acids are present, which may be quickly determined with alcoholic N/10 sodium hydroxide.
INSOLUBLE MATTER.
The insoluble matter in soap may consist of organic or inorganic substances. Among the organic substances which are usually present in soap are oat meal, bran, sawdust, etc., while among the common inorganic or mineral compounds are pumice, silex, clay, talc, zinc oxide, infusorial earth, sand or other material used as fillers.
To determine insoluble matter, 5 grams of soap are dissolved in 75 cubic centimeters of hot water. The solution is filtered through a weighed gooch crucible or filter paper. The residue remaining on the filter is washed with hot water until all the soap is removed, is then dried to constant weight at 105 degrees C. and weighed. From the difference in weight of the gooch or filter paper and the dried residue remaining thereon after filtering and drying, the total percentage of insoluble matter may easily be calculated. By igniting the residue and reweighing the amount of insoluble mineral matter can be readily determined.
STARCH AND GELATINE.
Should starch or gelatine be present in soap it is necessary to extract 5 grams of the soap with 100 cubic centimeters of 95 per cent. neutralized alcohol in a Soxhlet extractor until the residue on the extraction thimble is in a powder form. If necessary the apparatus should be disconnected and any lumps crushed, as these may contain soap. The residue remaining on the thimble consists of all substances present in soap, insoluble in alcohol. This is dried and weighed so that any percentage of impurities not actually determined can be found by difference. Starch and gelatine are separated from carbonate, sulfate and borate by dissolving the latter out through a filter with cold water. The starch and gelatine thus remaining can be determined by known methods, starch by the method of direct hydrolysis[15] and gelatine by Kjeldahling and calculating the corresponding amount of gelatine from the percentage of nitrogen (17.9%) therein.[16]
TOTAL FATTY AND RESIN ACIDS.
To the filtrate from the insoluble matter add 40 cubic centimeters of half normal sulfuric acid, all the acid being added at once. Boil, stir thoroughly for some minutes and keep warm on a water bath until the fatty acids have collected as a clear layer on the surface. Cool by placing the beaker in ice and syphon off the acid water through a filter. Should the fatty acids not readily congeal a weighed amount of dried bleached bees-wax or stearic acid may be added to the hot mixture. This fuses with the hot mass and forms a firm cake of fatty acids upon cooling. Without removing the fatty acids from the beaker, add about 300 cubic centimeters of hot water, cool, syphon off the water through the same filter used before and wash again. Repeat washing, cooling and syphoning processes until the wash water is no longer acid. When this stage is reached, dissolve any fatty acid which may have remained on the filter with hot 95 per cent. alcohol into the beaker containing the fatty acids. Evaporate the alcohol and dry the beaker to constant weight over a water bath. The fatty acids thus obtained represent the combined fatty acids, uncombined fat and hydrocarbons.
DETERMINATION OF ROSIN.
If resin acids are present, this may be determined by the Liebermann-Storch reaction. To carry out this test shake 2 cubic centimeters of the fatty acids with 5 cubic centimeters of acetic anhydride; warm slightly; cool; draw off the anhydride and add 1:1 sulfuric acid. A violet color, which is not permanent, indicates the presence of rosin in the soap. The cholesterol in linseed or fish oil, which of course may be present in the soap, also give this reaction.
Should resin acids be present, these may be separated by the Twitchell method, which depends upon the difference in the behavior of the fatty and resin acids when converted into their ethyl esters through the
## action of hydrochloric acid. This may be carried out as follows:
Three grams of the dried mixed acids are dissolved in 25 cubic centimeters of absolute alcohol in a 100 cubic centimeter stoppered flask; the flask placed in cold water and shaken. To this cooled solution 25 cubic centimeters of absolute alcohol saturated with dry hydrochloric acid is added. The flask is shaken occasionally and the
## action allowed to continue for twenty minutes, then 10 grams of dry
granular zinc chloride are added, the flask shaken and again allowed to stand for twenty minutes. The contents of the flask are then poured into 200 cubic centimeters of water in a 500 cubic centimeter beaker and the flask rinsed out with alcohol. A small strip of zinc is placed in the beaker and the alcohol evaporated. The beaker is then cooled and transferred to a separatory funnel, washing out the beaker with 50 cubic centimeters of gasoline (boiling below 80 degrees C.) and extracting by shaking the funnel well. Draw off the acid solution after allowing to separate and wash the gasoline with water until free from hydrochloric acid. Draw off the gasoline solution and evaporate the gasoline. Dissolve the residue in neutral alcohol and titrate with standard alkali using phenolphthalein as an indicator. One cubic centimeter of normal alkali equals 0.346 grams of rosin. The rosin may be gravimetrically determined by washing the gasoline extract with water, it not being necessary to wash absolutely free from acid, then adding 0.5 gram of potassium hydroxide and 5 cubic centimeters of alcohol in 50 cubic centimeters of water. Upon shaking the resin acids are rapidly saponified and extracted by the dilute alkaline solution as rosin soaps, while the ethyl esters remain in solution in the gasoline. Draw off the soap solution, wash the gasoline solution again with dilute alkali and unite the alkaline solutions. Decompose the alkaline soap solution with an excess of hydrochloric acid and weigh the resin acids liberated as in the determination of total fatty acids.
According to Lewkowitsch, the results obtained by the volumetric method which assumes a combining weight of 346 for resin acids, are very likely to be high. On the other hand those obtained by the gravimetric method are too low.
Leiste and Stiepel[17] have devised a simpler method for the determination of rosin. They make use of the fact that the resin acids as sodium soaps are soluble in acetone and particularly acetone containing two per cent. water, while the fatty acid soaps are soluble in this solvent to the extent of only about 2 per cent. First of all it is necessary to show that the sample to be analyzed contains a mixture of resin and fatty acids. This may be done by the Liebermann-Storch reaction already described. Glycerine interferes with the method. Two grams of fatty acids or 3 grams of soap are weighed in a nickel crucible and dissolved in 15-20 cubic centimeters of alcohol. The solution is then neutralized with alcoholic sodium hydroxide, using phenolphthalein as an indicator. The mass is concentrated by heat over an asbestos plate until a slight film forms over it. Then about 10 grams of sharp, granular, ignited sand are stirred in by means of a spatula, the alcohol further evaporated, the mixture being constantly stirred and then thoroughly dried in a drying oven. The solvent for the cooled mass is acetone containing 2 per cent. water. It is obtained from acetone dried by ignited sodium sulfate and adding 2 per cent. water by volume. One hundred cubic centimeters of this solvent are sufficient for extracting the above. The extraction of the rosin soap is conducted by adding 10 cubic centimeters of acetone eight times, rubbing the mass thoroughly with a spatula and decanting. The decanted portions are combined in a beaker and the suspended fatty soaps allowed to separate. The mixture is then filtered into a previously weighed flask and washed several times with the acetone remaining. The solution of rosin soap should show no separation of solid matter after having evaporated to half the volume and allowing to cool. If a separation should occur another filtration and the slightest possible washing is necessary. To complete the analysis, the acetone is completely evaporated and the mass dried to constant weight in a drying oven. The weight found gives the weight of the rosin soap. In conducting the determination, it is important to dry the mixture of soap and sand thoroughly. In dealing with potash soaps it is necessary to separate the fatty acids from these and use them as acetone dissolves too great a quantity of a potash soap.
TOTAL ALKALI.
In the filtrate remaining after having washed the fatty acids in the determination of total fatty and resin acids all the alkali present as soap, as carbonate and as hydroxide remains in solution as sulfate. Upon titrating this solution with half normal alkali the difference between the half normal acid used in decomposing the soap and alkali used in titrating the excess of acid gives the amount of total alkali in the soap. By deducting the amount of free alkali present as carbonate or hydroxide previously found the amount of combined alkali in the soap may be calculated.
To quickly determine total alkali in soap a weighed portion of the soap may be ignited to a white ash and the ash titrated for alkalinity using methyl orange as an indicator.
UNSAPONIFIED MATTER.
Dissolve 5 grams of soap in 50 cubic centimeters of 50 per cent. alcohol. Should any free fatty acids be present neutralize them with standard alkali. Wash into a separatory funnel with 50 per cent. alcohol and extract with 100 cubic centimeters of gasoline, boiling at 50 degrees to 60 degrees C. Wash the gasoline with water, draw off the watery layer. Run the gasoline into a weighed dish, evaporate the alcohol, dry and weigh the residue as unsaponified matter. The residue contains any hydrocarbon oils or fats not converted into soap.
SILICA AND SILICATES.
The insoluble silicates, sand, etc., are present in the ignited residue in the determination of insoluble matter. Sodium silicate, extensively used as a filler, however, will only show itself in forming a pasty liquid. Where it is desired to determine sodium silicate, 10 grams of soap are ashed by ignition, hydrochloric acid added to the ash in excess and evaporated to dryness. More hydrochloric acid is then added and the mass is again evaporated until dry; then cooled; moistened with hydrochloric acid; dissolved in water; filtered; washed; the filtrate evaporated to dryness and again taken up with hydrochloric acid and water; filtered and washed. The precipitates are then combined and ignited. Silicon dioxide (SiO_{2}) is thus formed, which can be calculated to sodium silicate (Na_{2}Si_{4}O_{9}). Should other metals than alkali metals be suspected present the filtrate from the silica determinations should be examined.
GLYCERINE IN SOAP.
To determine the amount of glycerine contained in soap dissolve 25 grams in hot water, add a slight excess of sulfuric acid and keep hot until the fatty acids form as a clear layer on top. Cool the mass and remove the fatty acids. Filter the acid solution into a 25 cubic centimeter graduated flask; bring to the mark with water and determine the glycerine by the bichromate method as described under glycerine analysis.
When sugar is present the bichromate would be reduced by the sugar, hence this method is not applicable. In this case remove the fatty acids as before, neutralize an aliquot portion with milk of lime, evaporate to 10 cubic centimeters, add 2 grams of sand and milk of lime containing about 2 grams of calcium hydroxide and evaporate almost to dryness. Treat the moist residue with 5 cubic centimeters of 96 per cent. alcohol, rub the whole mass into a paste, then constantly stirring, heat on a water bath and decant into a 250 cubic centimeter graduated flask. Repeat the washing with 5 cubic centimeters of alcohol five or six times, each time pouring the washings into the flask; cool the flask to room temperature and fill to the mark with 96 per cent. alcohol, agitate the flask until well mixed and filter through a dry filter paper. Take 200 cubic centimeters of the nitrate and evaporate to a syrupy consistency over a safety water bath. Wash the liquor into a stoppered flask with 20 cubic centimeters of absolute alcohol, add 30 cubic centimeters of absolute ether 10 cubic centimeters at a time, shaking well after each addition and let stand until clear. Pour off the solution through a filter into a weighed dish and wash out the flask with a mixture of three parts absolute ether and two parts absolute alcohol. Evaporate to a syrup, dry for one hour at the temperature of boiling water, weigh, ignite and weigh again. The loss is glycerine. This multiplied by 5/4 gives the total loss for the aliquot portion taken. The glycerine may also be determined by the acetin or bichromate methods after driving off the alcohol and ether if so desired.
SUGAR IN SOAP.
To determine sugar in soap, usually present in transparent soaps, decompose a soap solution of 5 grams of soap dissolved in 100 cubic centimeters of hot water with an excess of hydrochloric acid and separate the fatty acids as usual. Filter the acid solution into a graduated flask and make up to the mark. Take an aliquot containing approximately 1 per cent. of reducing sugar and determine the amount of sugar by the Soxhlet method.[18]
GLYCERINE ANALYSIS.
The methods of analyzing glycerine varied so greatly due to the fact that glycerine contained impurities which acted so much like glycerine as to introduce serious errors in the determinations of crude glycerine. This led to the appointment of committees in the United States and Europe to investigate the methods of glycerine analysis. An international committee met after their investigations and decided the acetin method should control the buying and selling of glycerine, but the more convenient bichromate method in a standardized form might be used in factory control and other technical purposes. The following are the methods of analysis and sampling as suggested by the international committee:
SAMPLING.
The most satisfactory method available for sampling crude glycerine liable to contain suspended matter, or which is liable to deposit salt on settling, is to have the glycerine sampled by a mutually approved sampler as soon as possible after it is filled into drums, but in any case before any separation of salt has taken place. In such cases he shall sample with a sectional sampler (see appendix) then seal the drums, brand them with a number for identification, and keep a record of the brand number. The presence of any visible salt or other suspended matter is to be noted by the sampler, and a report of the same made in his certificate, together with the temperature of the glycerine. Each drum must be sampled. Glycerine which has deposited salt or other solid matter cannot be accurately sampled from the drums, but an approximate sample can be obtained by means of the sectional sampler, which will allow a complete vertical section of the glycerine to be taken including any deposit.
ANALYSIS.
1. _Determination of Free Caustic Alkali._--Put 20 grams of the sample into a 100 cc. flask, dilute with approximately 50 cc. of freshly boiled distilled water, add an excess of neutral barium chloride solution, 1 cc. of phenolphthalein solution, make up to the mark and mix. Allow the precipitate to settle, draw off 50 cc. of the clear liquid and titrate with normal acid (_N_/1). Calculate the percentage of Na_{2}O existing as caustic alkali.
2. _Determination of Ash and Total Alkalinity._--Weigh 2 to 5 grams of the sample in a platinum dish, burn off the glycerine over a luminous Argand burner or other source of heat,[19] giving a low temperature, to avoid volatilization and the formation of sulphides. When the mass is charred to the point that water will not be colored by soluble organic matter, lixiviate with hot distilled water, filter, wash and ignite the residue in the platinum dish. Return the filtrate and washings to the dish, evaporate the water, and carefully ignite without fusion. Weigh the ash.
Dissolve the ash in distilled water and titrate total alkalinity, using as indicator methyl orange cold or litmus boiling.
3. _Determination of Alkali Present as Carbonate._--Take 10 grams of the sample, dilute with 50 cc. distilled water, add sufficient _N_/1 acid to neutralize the total alkali found at (2), boil under a reflux condenser for 15 to 20 minutes, wash down the condenser tube with distilled water, free from carbon dioxide, and then titrate back with _N_/1 NaOH, using phenolphthalein as indicator. Calculate the percentage of Na_{2}O. Deduct the Na_{2}O found in (1). The difference is the percentage of Na_{2}O existing as carbonate.
4. _Alkali Combined with Organic Acids._--The sum of the percentages of Na_{2}O found at (1) and (3) deducted from the percentage found at (2) is a measure of the Na_{2}O or other alkali combined with organic acids.
5. _Determination of Acidity._--Take 10 grams of the sample, dilute with 50 cc. distilled water free from carbon dioxide, and titrate with _N_/1 NaOH and phenolphthalein. Express in terms of Na_{2}O required to neutralize 100 grams.
6. _Determination of Total Residue at 160deg. C._--For this determination the crude glycerine should be slightly alkaline with Na_{2}CO_{3} not exceeding 0.2 per cent. Na_{2}O, in order to prevent loss of organic acids. To avoid the formation of polyglycerols this alkalinity must not be exceeded.
Ten grams of the sample are put into a 100 cc. flask, diluted with water and the calculated quantity of _N_/1 HCl or Na_{2}CO_{3} added to give the required degree of alkalinity. The flask is filled to 100 cc., the contents mixed, and 10 cc. measured into a weighed Petrie or similar dish 2.5 in. in diameter and 0.5 in. deep, which should have a flat bottom. In the case of crude glycerine abnormally high in organic residue a smaller amount should be taken, so that the weight of the organic residue does not materially exceed 30 to 40 milligrams.
The dish is placed on a water bath (the top of the 160deg. oven acts equally well) until most of the water has evaporated. From this point the evaporation is effected in the oven. Satisfactory results are obtained in an oven[20] measuring 12 ins. cube, having an iron plate 0.75 in. thick lying on the bottom to distribute the heat. Strips of asbestos millboard are placed on a shelf half way up the oven. On these strips the dish containing the glycerine is placed.
If the temperature of the oven has been adjusted to 160deg. C. with the door closed, a temperature of 130deg. to 140deg. can be readily maintained with the door partially open, and the glycerine, or most of it, should be evaporated off at this temperature. When only a slight vapor is seen to come off, the dish is removed and allowed to cool.
An addition of 0.5 to 1.0 cc. of water is made, and by a rotary motion the residue brought wholly or nearly into solution. The dish is then allowed to remain on a water bath or top of the oven until the excess water has evaporated and the residue is in such a condition that on returning to the oven at 160deg. C. it will not spurt. The time taken up to this point cannot be given definitely, nor is it important. Usually two or three hours are required. From this point, however, the schedule of time must be strictly adhered to. The dish is allowed to remain in the oven, the temperature of which is carefully maintained at 160deg. C. for one hour, when it is removed, cooled, the residue treated with water, and the water evaporated as before. The residue is then subjected to a second baking of one hour, after which the dish is allowed to cool in a desiccator over sulphuric acid and weighed. The treatment with water, etc., is repeated until a constant loss of 1 to 1.5 mg. per hour is obtained.
In the case of acid glycerine a correction must be made for the alkali added 1 cc. _N_/1 alkali represents an addition of 0.03 gram. In the case of alkaline crudes a correction should be made for the acid added. Deduct the increase in weight due to the conversion of the NaOH and Na_{2}CO_{3} to NaCl. The corrected weight multiplied by 100 gives the percentage of _total residue at 160deg. C._
This residue is taken for the determination of the non-volatile acetylizable impurities (see acetin method).
7. _Organic residue._--Subtract the ash from the total residue at 160deg. C. Report as organic residue at 160deg. C. (it should be noted that alkaline salts of fatty acids are converted to carbonates on ignition and that the CO_{3} thus derived is not included in the organic residue).
ACETIN PROCESS FOR THE DETERMINATION OF GLYCEROL.
This process is the one agreed upon at a conference of delegates from the British, French, German and American committees, and has been confirmed by each of the above committees as giving results nearer to the truth than the bichromate method on crudes in general. It is the process to be used (if applicable) whenever only one method is employed. On pure glycerines the results are identical with those obtained by the bichromate process. For the application of this method the crude glycerine should not contain over 60 per cent. water.
REAGENTS REQUIRED.
(_A_) _Best Acetic Anhydride._--This should be carefully selected. A good sample must not require more than 0.1 cc. normal NaOH for saponification of the impurities when a blank is run on 7.5 cc. Only a slight color should develop during digestion of the blank.
The anhydride may be tested for strength by the following method: Into a weighed stoppered vessel, containing 10 to 20 cc. of water, run about 2 cc. of the anhydride, replace the stopper and weigh. Let stand with occasional shaking, for several hours, to permit the hydrolysis of all the anhydride; then dilute to about 200 cc., add phenolphthalein and titrate with _N_/1 NaOH. This gives the total acidity due to free acetic acid and acid formed from the anhydride. It is worthy of note that in the presence of much free anhydride a compound is formed with phenolphthalein, soluble in alkali and acetic acid, but insoluble in neutral solutions. If a turbidity is noticed toward the end of the neutralization it is an indication that the anhydride is incompletely hydrolyzed and inasmuch as the indicator is withdrawn from the solution, results may be incorrect.
Into a stoppered weighing bottle containing a known weight of recently distilled aniline (from 10 to 20 cc.) measure about 2 cc. of the sample, stopper, mix, cool and weigh. Wash the contents into about 200 cc. of cold water, and titrate the acidity as before. This yields the acidity due to the original, preformed, acetic acid plus one-half the acid due to anhydride (the other half having formed acetanilide); subtract the second result from the first (both calculated to 100 grams) and double the result, obtaining the cc. _N_/1 NaOH per 100 grams of the sample. 1 cc. _N_/NaOH equals 0.0510 anhydride.
(_B_) _Pure Fused Sodium Acetate._--The purchased salt is again completely fused in a platinum, silica or nickel dish, avoiding charring, powdered quickly and kept in a stoppered bottle or desiccator. It is most important that the sodium acetate be anhydrous.
(_C_) _A Solution of Caustic Soda for Neutralizing, of about N_/1 _Strength, Free from Carbonate._--This can be readily made by dissolving pure sodium hydroxide in its own weight of water (preferably water free from carbon dioxide) and allowing to settle until clear, or filtering through an asbestos or paper filter. The clear solution is diluted with water free from carbon dioxide to the strength required.
(_D_) _N_/1 _Caustic Soda Free from Carbonate._--Prepared as above and carefully standardized. Some caustic soda solutions show a marked diminution in strength after being boiled; such solutions should be rejected.
(_E_) _N_/1 _Acid._--Carefully standardized.
(_F_) _Phenolphthalein Solution._--0.5 per cent. phenolphthalein in alcohol and neutralized.
THE METHOD.
In a narrow-mouthed flask (preferably round-bottomed), capacity about 120 cc., which has been thoroughly cleaned and dried, weigh accurately and as rapidly as possible 1.25 to 1.5 grams of the glycerine. A Grethan or Lunge pipette will be found convenient. Add about 3 grams of the anhydrous sodium acetate, then 7.5 cc. of the acetic anhydride, and connect the flask with an upright Liebig condenser. For convenience the inner tube of this condenser should not be over 50 cm. long and 9 to 10 mm. inside diameter. The flask is connected to the condenser by either a ground glass joint (preferably) or a rubber stopper. If a rubber stopper is used it should have had a preliminary treatment with hot acetic anhydride vapor.
Heat the contents and keep just boiling for one hour, taking precautions to prevent the salts drying on the sides of the flask.
Allow the flask to cool somewhat, and through the condenser tube add 50 cc. of distilled water free from carbon dioxide at a temperature of about 80deg. C., taking care that the flask is not loosened from the condenser. The object of cooling is to avoid any sudden rush of vapors from the flask on adding water, and to avoid breaking the flask. Time is saved by adding the water before the contents of the flask solidify, but the contents may be allowed to solidify and the test proceeded with the next day without detriment, bearing in mind that the anhydride in excess is much more effectively hydrolyzed in hot than in cold water. The contents of the flask may be warmed to, but must not exceed, 80deg. C., until the solution is complete, except a few dark flocks representing organic impurities in the crude. By giving the flask a rotary motion, solution is more quickly effected.
Cool the flask and contents without loosening from the condenser. When quite cold wash down the inside of the condenser tube, detach the flask, wash off the stopper or ground glass connection into the flask, and filter the contents through an acid-washed filter into a Jena glass flask of about 1 litre capacity. Wash thoroughly with cold distilled water free from carbon dioxide. Add 2 cc. of phenolphthalein solution (_F_), then run in caustic soda solution (_C_) or (_D_) until a faint pinkish yellow color appears throughout the solution. This neutralization must be done most carefully; the alkali should be run down the sides of the flask, the contents of which are kept rapidly swirling with occasional agitation or change of motion until the solution is nearly neutralized, as indicated by the slower disappearance of the color developed locally by the alkali running into the mixture. When this point is reached the sides of the flask are washed down with carbon dioxide-free water and the alkali subsequently added drop by drop, mixing after each drop until the desired tint is obtained.
Now run in from a burette 50 cc. or a calculated excess of _N_/1 NaOH (_D_) and note carefully the exact amount. Boil gently for 15 minutes, the flask being fitted with a glass tube acting as a partial condenser. Cool as quickly as possible and titrate the excess of NaOH with _N_/1 acid (_E_) until the pinkish yellow or chosen end-point color just remains.[21] A further addition of the indicator at this point will cause an increase of the pink color; this must be neglected, and the first end-point taken.
From the _N_/1 NaOH consumed calculate the percentage of glycerol (including acetylizable impurities) after making the correction for the blank test described below.
1 cc. _N_/1 NaOH = 0.03069 gram glycerol.
The coefficient of expansion for normal solutions is 0.00033 per cc. for each degree centigrade. A correction should be made on this account if necessary.
_Blank Test._--As the acetic anhydride and sodium acetate may contain impurities which affect the result, it is necessary to make a blank test, using the same quantities of acetic anhydride, sodium acetate and water as in the analysis. It is not necessary to filter the solution of the melt in this case, but sufficient time must be allowed for the hydrolysis of the anhydride before proceeding with the neutralization. After neutralization it is not necessary to add more than 10 cc. of the _N_/1 alkali (_D_), as this represents the excess usually present after the saponification of the average soap lye crude. In determining the acid equivalent of the _N_/1 NaOH, however, the entire amount taken in the analysis, 50 cc., should be titrated after dilution with 300 cc. water free from carbon dioxide and without boiling.
_Determination of the Glycerol Value of the Acetylizable Impurities._--The total residue at 160deg. C. is dissolved in 1 or 2 cc. of water, washed into the acetylizing flask and evaporated to dryness. Then add anhydrous sodium acetate and acetic anhydride in the usual amounts and proceed as described in the regular analysis. After correcting for the blank, calculate the result to glycerol.
WAYS OF CALCULATING ACTUAL GLYCEROL CONTENT.
(1) Determine the apparent percentage of glycerol in the sample by the acetin process as described. The result will include acetylizable impurities if any are present.
(2) Determine the total residue at 160deg. C.
(3) Determine the acetin value of the residue at (2) in terms of glycerol.
(4) Deduct the result found at (3) from the percentage obtained at (1) and report this corrected figure as glycerol. If volatile acetylizable impurities are present these are included in this figure.
Trimethyleneglycol is more volatile than glycerine and can therefore be concentrated by fractional distillation. An approximation to the quantity can be obtained from the spread between the acetin and bichromate results on such distillates. The spread multiplied by 1.736 will give the glycol.
BICHROMATE PROCESS FOR GLYCEROL DETERMINATION. REAGENTS REQUIRED.
(_A_) _Pure potassium bichromate_ powdered and dried in air free from dust or organic vapors, at 110deg. to 120deg. C. This is taken as the standard.
(_B_) _Dilute Bichromate Solution._--7.4564 grams of the above bichromate are dissolved in distilled water and the solution made up to one liter at 15.5deg. C.
(_C_) _Ferrous Ammonium Sulphate._--It is never safe to assume this salt to be constant in composition and it must be standardized against the bichromate as follows: dissolve 3.7282 grams of bichromate (_A_) in 50 cc. of water. Add 50 cc. of 50 per cent. sulphuric acid (by volume), and to the cold undiluted solution add from a weighing bottle a moderate excess of the ferrous ammonium sulphate, and titrate back with the dilute bichromate (_B_). Calculate the value of the ferrous salt in terms of bichromate.
(_D_) _Silver Carbonate._--This is prepared as required for each test from 140 cc. of 0.5 per cent. silver sulphate solution by precipitation, with about 4.9 cc. _N_/1 sodium carbonate solution (a little less than the calculated quantity of _N_/1 sodium carbonate should be used as an excess to prevent rapid settling). Settle, decant and wash one by decantation.
(_E_) _Subacetate of Lead._--Boil a 10 per cent. solution of pure lead acetate with an excess of litharge for one hour, keeping the volume constant, and filter while hot. Disregard any precipitate which subsequently forms. Preserve out of contact with carbon dioxide.
(_F_) _Potassium Ferricyanide._--A very dilute, freshly prepared solution containing about 0.1 per cent.
THE METHOD.
Weigh 20 grams of the glycerine, dilute to 250 cc. and take 25 cc. Add the silver carbonate, allow to stand, with occasional agitation, for about 10 minutes, and add a slight excess (about 5 cc. in most cases) of the basic lead acetate (_E_), allow to stand a few minutes, dilute with distilled water to 100 cc., and then add 0.15 cc. to compensate for the volume of the precipitate, mix thoroughly, filter through an air-dry filter into a suitable narrow-mouthed vessel, rejecting the first 10 cc., and return the filtrate if not clear and bright. Test a portion of the filtrate with a little basic lead acetate, which should produce no further precipitate (in the great majority of cases 5 cc. are ample, but occasionally a crude will be found requiring more, and in this case another aliquot of 25 cc. of the dilute glycerine should be taken and purified with 6 cc. of the basic acetate). Care must be taken to avoid a marked excess of basic acetate.
Measure off 25 cc. of the clear filtrate into a flask or beaker (previously cleaned with potassium bichromate and sulphuric acid). Add 12 drops of sulphuric acid (1: 4) to precipitate the small excess of lead as sulphate. Add 3.7282 grams of the powdered potassium bichromate (_A_). Rinse down the bichromate with 25 cc. of water and let stand with occasional shaking until all the bichromate is dissolved (no reduction will take place in the cold).
Now add 50 cc. of 50 per cent. sulphuric acid (by volume) and immerse the vessel in boiling water for two hours and keep protected from dust and organic vapors, such as alcohol, till the titration is completed. Add from a weighing bottle a slight excess of the ferrous ammonium sulphate (_C_), making spot tests on a porcelain plate with the potassium ferricyanide (_F_). Titrate back with the dilute bichromate. From the amount of bichromate reduced calculate the percentage of glycerol.
1 gram glycerol = 7.4564 grams bichromate.
1 gram bichromate = 0.13411 gram glycerol.
The percentage of glycerol obtained above includes any oxidizable impurities present after the purification. A correction for the non-volatile impurities may be made by running a bichromate test on the residue at 160deg. C.
NOTES.
(1) It is important that the concentration of acid in the oxidation mixture and the time of oxidation should be strictly adhered to.
(2) Before the bichromate is added to the glycerine solution it is essential that the slight excess of lead be precipitated with sulphuric acid, as stipulated.
(3) For crudes practically free from chlorides the quantity of silver carbonate may be reduced to one-fifth and the basic lead acetate to 0.5 cc.
(4) It is sometimes advisable to add a little potassium sulphate to insure a clear filtrate.
SAMPLING CRUDE GLYCERINE.
The usual method of sampling crude glycerine hitherto has been by means of a glass tube, which is slowly lowered into the drum with the object of taking as nearly as possible a vertical section of the glycerine contained in the drum. This method has been found unsatisfactory, owing to the fact that in cold climates glycerine runs into the tube very slowly, so that, owing to the time occupied, it is impossible to take a complete section of the crude. Another objection to the glass tube is that it fails to take anything approaching a correct proportion of any settled salt contained in the drum.
The sampler which is illustrated herewith has been devised with the object of overcoming the objections to the glass tube as far as possible. It consists of two brass tubes, one fitting closely inside the other. A number of ports are cut out in each tube in such a way that when the ports are opened a continuous slot is formed which enables a complete section to be taken throughout the entire length of the drum. By this arrangement the glycerine fills into the sampler almost instantaneously. There are a number of ports cut at the bottom of the sampler which render it possible to take a proportion of the salt at the bottom of the drum. The instrument is so constructed that all the ports, including the bottom ones, can be closed simultaneously by the simple
## action of turning the handle at the top; a pointer is arranged which
indicates on a dial when the sampler is open or closed. In samplers of larger section (1 in.) it is possible to arrange a third motion whereby the bottom ports only are open for emptying, but in samplers of smaller dimensions (5/8 in.) this third motion must be dispensed with, otherwise the dimensions of the ports have to be so small that the sampler would not be efficient.
In using the sampler it is introduced into the drum with the ports closed, and when it has touched the bottom, the ports are opened for a second or two, then closed and withdrawn, and the sample discharged into the receiving vessel by opening the ports. When the drum contains salt which has deposited, the ports must be opened before the sampler is pushed through the salt, thus enabling a portion to be included in the sample. It is, however, almost impossible to obtain a correct proportion of salt after it has settled in the drum and it is therefore recommended that the drum be sampled before any salt has deposited. A sampler 1 in. in diameter withdraws approximately 10 oz. from a 110-gal. drum. A sampler 5/8 in. in diameter will withdraw about 5 oz.
FOOTNOTES:
[13] Zeit. Angew. Chem. 19, 385 (1906).
[14] Zeit. Angew. Chem. 27, 11-20 (1914).
[15] Bull. 107, Bur. Chem. U. S. Dept. Agriculture.
[16] Richards and Gies, Am. J. Physiol. (1902) 7, 129.
[17] Seifensieder Ztg. (1913) No. 46.
[18] Bull 107, Bur. Chem. U. S. Dept. Agriculture.
[19] Carbon is readily burned off completely, without loss of chlorides, in a gas-heated muffle furnace adjusted to a dull red heat.
[20] An electric oven suitable for this work, which is readily adjusted to 160 degs. C., has been made for Mr. Low and the chairman, by the Apparatus and Specialty Company, Lansing, Mich. Its size is 9-1/2 x 10 x 16 inches, and capacity 8 Petrie dishes. It gives a strong draft at constant temperature.
[21] A precipitate at this point is an indication of the presence of iron or alumina, and high results will be obtained unless a correction is made as described below.
## CHAPTER VII
Standard Methods for the Sampling and Analysis of Commercial Fats and Oils[22]
The following report of the _Committee on Analysis of Commercial Fats and Oils_ of the _Division of Industrial Chemists and Chemical Engineers_ of the American Chemical Society was adopted April 14, 1919, by unanimous vote:
W. D. RICHARDSON, _Chairman_, Swift and Co., Chicago, Ill.
R. W. BAILEY, Stillwell and Gladding, New York City.
W. J. GASCOYNE, W. J. Gascoyne and Co., Baltimore, Md.
I. KATZ,[A] Wilson and Co., Chicago, Ill.
A. LOWENSTEIN,[A] Morris and Co., Chicago, Ill.
H. J. MORRISON, Proctor and Gamble Co., Ivorydale, Ohio.
J. R. POWELL, Armour Soap Works, Chicago, Ill.
R. J. QUINN,[A] Midland Chemical Co., Argo, Ill.
PAUL RUDNICK, Armour and Co., Chicago, Ill.
L. M. TOLMAN, Wilson and Co., Chicago, Ill.
E. TWITCHELL,[A] Emery Candle Co., Cincinnati, Ohio.
J. J. VOLLERTSEN, Morris and Co., Chicago, Ill.
[Note A: Resigned.]
Scope, Applicability and Limitations of the Methods.
SCOPE.
These methods are intended to aid in determining the commercial valuation of fats and fatty oils in their purchase and sale, based on the fundamental assumption commonly recognized in the trade, namely, that the product is true to name and is not adulterated. For methods for determining the identity of oils and fats, the absence of adulterants therein and for specific tests used in particular industries, the chemist is referred to standard works on the analysis of fats and oils.
APPLICABILITY.
The methods are applicable in commercial transactions involving fats and fatty oils used in the soap, candle and tanning industries, to edible fats and oils and to fats and fatty oils intended for lubricating and burning purposes. The methods are applicable to the raw oils used in the varnish and paint industry with the exceptions noted under limitations, but special methods have not been included.
LIMITATIONS.
The methods have not been developed with special reference to waxes (beeswax, carnauba wax, wool wax, etc.) although some of them may be found applicable to these substances. The Committee considers the Wijs method superior to the Hanus method for the determination of iodine number of linseed oil as well as other oils, although the Hanus method has been considered standard for this work for some time and has been adopted by the American Society for Testing Materials and in various specifications. It has been customary to use the Huebl method for the determination of iodine value of tung oil (China wood oil) but the Committee's work indicates that the Wijs method is satisfactory for this determination.
Sampling.
TANK CARS.
1. SAMPLING WHILE LOADING--Sample shall be taken at discharge of pipe where it enters tank car dome. The total sample taken shall be not less than 50 lbs. and shall be a composite of small samples of about 1 pound each, taken at regular intervals during the entire period of loading.
The sample thus obtained is thoroughly mixed and uniform 3-lb. portions placed in air-tight 3-lb. metal containers. At least three such samples shall be put up, one for the buyer, one for the seller, and the third to be sent to a referee chemist in case of dispute. All samples are to be promptly and correctly labeled and sealed.
2. SAMPLING FROM CAR ON TRACK[23]--(_a_) _When contents are solid._[24] In this case the sample is taken by means of a large tryer measuring about 2 in. across and about 1-1/2 times the depth of the car in length. Several tryerfuls are taken vertically and obliquely toward the ends of the car until 50 lbs. are accumulated, when the sample is softened, mixed and handled as under (1). In case the contents of the tank car have assumed a very hard condition, as in Winter weather, so that it is impossible to insert the tryer, and it becomes necessary to soften the contents of the car by means of the closed steam coil (in nearly all tank cars the closed steam coil leaks) or by means of open steam in order to draw a proper sample, suitable arrangements must be made between buyer and seller for the sampling of the car after it is sufficiently softened, due consideration being given to the possible presence of water in the material in the car as received and also to the possible addition of water during the steaming. The Committee knows of no direct method for sampling a hard-frozen tank car of tallow in a satisfactory manner.
(_b_) _When contents are liquid._ The sample taken is to be a 50-lb. composite made up of numerous small samples taken from the top, bottom and intermediate points by means of a bottle or metal container with removable stopper or top. This device attached to a suitable pole is lowered to the various desired depths, when the stopper or top is removed and the container allowed to fill. The 50-lb. sample thus obtained is handled as under (1).
In place of the device described above, any sampler capable of taking a sample from the top, bottom, and center, or from a section through car, may be used.
(_c_) _When contents are in semi-solid condition, or when stearine has separated from liquid portions._ In this case, a combination of (_a_) and (_b_) may be used or by agreement of the parties the whole may be melted and procedure (_b_) followed.
BARRELS, TIERCES, CASKS, DRUMS, AND OTHER PACKAGES.
All packages shall be sampled, unless by special agreement the parties arrange to sample a lesser number; but in any case not less than 10 per cent of the total number shall be sampled. The total sample taken shall be at least 20 lbs. in weight for each 100 barrels, or equivalent.
1. BARRELS, TIERCES AND CASKS--(_a_) _When contents are solid._ The small samples shall be taken by a tryer through the bunghole or through a special hole bored in the head or side for the purpose, with a 1-in. or larger auger. Care should be taken to avoid and eliminate all borings and chips from the sample. The tryer is inserted in such a way as to reach the head of the barrel, tierce, or cask. The large sample is softened, mixed and handled according to TANK CARS (1).
(_b_) _When contents are liquid._ In this case use is made of a glass tube with constricted lower end. This is inserted slowly and allowed to fill with the liquid, when the upper end is closed and the tube withdrawn, the contents being allowed to drain into the sample container. After the entire sample is taken it is thoroughly mixed and handled according to TANK CARS (1).
(_c_) _When contents are semi-solid._ In this case the tryer or a glass tube with larger outlet is used, depending on the degree of fluidity.
(_d_) _Very hard materials, such as natural and artificial stearines._ By preference the barrels are stripped and samples obtained by breaking up contents of at least 10 per cent of the packages. This procedure is to be followed also in the case of cakes shipped in sacks. When shipped in the form of small pieces in sacks they can be sampled by grab sampling and quartering. In all cases the final procedure is as outlined under TANK CARS (1).
2. DRUMS--Samples are to be taken as under (1), use being made of the bunghole. The tryer or tube should be sufficiently long to reach to the ends of the drum.
3. OTHER PACKAGES--Tubs, pails and other small packages not mentioned above are to be sampled by tryer or tube (depending on fluidity) as outlined above, the tryer or tube being inserted diagonally whenever possible.
4. MIXED LOTS AND PACKAGES--When lots of tallow or other fats are received in packages of various shapes and sizes, and especially wherein the fat itself is of variable composition, such must be left to the judgment of the sampler. If variable, the contents of each package should be mixed as thoroughly as possible and the amount of the individual samples taken made proportional to the sizes of the packages.
Analysis.
SAMPLE.
The sample must be representative and at least three pounds in weight and taken in accordance with the STANDARD METHODS FOR THE SAMPLING OF COMMERCIAL FATS AND OILS. It must be kept in an air-tight container, in a dark, cool place.
Soften the sample if necessary by means of a gentle heat, taking care not to melt it. When sufficiently softened, mix the sample thoroughly by means of a mechanical egg beater or other equally effective mechanical mixer.
MOISTURE AND VOLATILE MATTER.
APPARATUS: _Vacuum Oven_--The Committee Standard Oven.
DESCRIPTION--The Standard F. A. C. Vacuum Oven has been designed with the idea of affording a simple and compact vacuum oven which will give as uniform temperatures as possible on the shelf. As the figure shows, it consists of an iron casting of rectangular sections with hinged front door made tight by means of a gasket and which can be lowered on opening the oven so as to form a shelf on which samples may be rested. The oven contains but one shelf which is heated from above as well as below by means of resistance coils. Several thermometer holes are provided in order to ascertain definitely the temperature at different points on the shelf. In a vacuum oven where the heating is done almost entirely by radiation it is difficult to maintain uniform temperatures at all points, but the F. A. C. oven accomplishes this rather better than most vacuum ovens. Larger ovens containing more than one shelf have been tried by the Committee, but have been found to be lacking in temperature uniformity and means of control. The entire oven is supported by means of a 4-in. standard pipe which screws into the base of the oven and which in turn is supported by being screwed into a blind flange of suitable diameter which rests on the floor or work table.
_Moisture Dish_--A shallow, glass dish, lipped, beaker form, approximately 6 to 7 cm. diameter and 4 cm. deep, shall be standard.
DETERMINATION--Weigh out 5 grams (= 0.2 g. of the prepared sample) into a moisture dish. Dry to constant weight in _vacuo_ at a uniform temperature, not less than 15deg. C. nor more than 20deg. C. above the boiling point of water at the working pressure, which must not exceed 100 mm. of mercury.[25] Constant weight is attained when successive dryings for 1-hr. periods show an additional loss of not more that 0.05 per cent. Report loss in weight as MOISTURE AND VOLATILE MATTER.[26]
[Illustration: STANDARD VACUUM OVEN]
The vacuum-oven method cannot be considered accurate in the case of fats of the coconut oil group containing free acid and the Committee recommends that it be used only for oils of this group when they contain less than 1 per cent free acid. In the case of oils of this group containing more than 1 per cent free acid, recourse should be had temporarily to the routine control method for moisture and volatile matter[27] until the Committee develops a more satisfactory method.
The air-oven method cannot be considered even approximately accurate in the case of the drying and semi-drying oils and those of the coconut oil group. Therefore, in the case of such oils as cottonseed oil, maize oil (corn oil), soy bean oil, linseed oil, coconut oil, palm kernel oil, etc., the vacuum-oven method should always be used, except in the case of fats of the coconut group containing more than 1 per cent free acid, as noted above.
INSOLUBLE IMPURITIES.
Dissolve the residue from the moisture and volatile matter determination by heating it on a steam bath with 50 cc. of kerosene. Filter the solution through a Gooch crucible properly prepared with asbestos,[28] wash the insoluble matter five times with 10-cc. portions of hot kerosene, and finally wash the residual kerosene out thoroughly with petroleum ether. Dry the crucible and contents to constant weight, as in the determination of moisture and volatile matter and report results as INSOLUBLE IMPURITIES.
SOLUBLE MINERAL MATTER.
Place the combined kerosene filtrate and kerosene washings from the insoluble impurities determination in a platinum dish. Place in this an ashless filter paper folded in the form of a cone, apex up. Light the apex of the cone, whereupon the bulk of the kerosene burns quietly. Ash the residue in a muffle, to constant weight, taking care that the decomposition of alkaline earth carbonates is complete, and report the result as SOLUBLE MINERAL MATTER.[29] When the percentage of soluble mineral matter amounts to more than 0.1 per cent, multiply the percentage by 10 and add this amount to the percentage of free fatty acids as determined.[30]
FREE FATTY ACIDS.
The ALCOHOL[31] used shall be approximately 95 per cent ethyl alcohol, freshly distilled from sodium hydroxide, which with phenolphthalein gives a definite and distinct end-point.
DETERMINATION--Weigh 1 to 15 g. of the prepared sample into an Erlenmeyer flask, using the smaller quantity in the case of dark-colored, high acid fats. Add 50 to 100 cc. hot, neutral alcohol, and titrate with _N_/2, _N_/4 or _N_/10 sodium hydroxide depending on the fatty acid content, using phenolphthalein as indicator. Calculate to oleic acid, except that in the case of palm oil the results may also be expressed in terms of palmitic acid, clearly indicating the two methods of calculation in the report. In the case of coconut and palm kernel oils, calculate to and report in terms of lauric acid in addition to oleic acid, clearly indicating the two methods of calculation in the report. In the case of fats or greases containing more than 0.1 per cent of soluble mineral matter, add to the percentages of free fatty acids as determined 10 times the percentage of bases in the soluble mineral matter as determined.[30] This addition gives the equivalent of fatty acids combined with the soluble mineral matter.
TITER.
STANDARD THERMOMETER--The thermometer is graduated at zero and in tenth degrees from 10deg. C. to 65deg. C., with one auxiliary reservoir at the upper end and another between the zero mark and the 10deg. mark. The cavity in the capillary tube between the zero mark and the 10deg. mark is at least 1 cm. below the 10deg. mark, the 10deg. mark is about 3 or 4 cm. above the bulb, the length of the thermometer being about 37 cm. over all. The thermometer has been annealed for 75 hrs. at 450deg. C. and the bulb is of Jena normal 16''' glass, or its equivalent, moderately thin, so that the thermometer will be quick-acting. The bulb is about 3 cm. long and 6 mm. in diameter. The stem of the thermometer is 6 mm. in diameter and made of the best thermometer tubing, with scale etched on the stem, the graduation is clear-cut and distinct, but quite fine. The thermometer must be certified by the U. S. Bureau of Standards.
GLYCEROL CAUSTIC SOLUTION--Dissolve 250 g. potassium hydroxide in 1900 cc. dynamite glycerin with the aid of heat.
DETERMINATION--Heat 75 cc. of the glycerol-caustic solution to 150deg. C. and add 50 g. of the melted fat. Stir the mixture well and continue heating until the melt is homogeneous, at no time allowing the temperature to exceed 150deg. C. Allow to cool somewhat and carefully add 50 cc. 30 per cent sulfuric acid. Now add hot water and heat until the fatty acids separate out perfectly clear. Draw off the acid water and wash the fatty acids with hot water until free from mineral acid, then filter and heat to 130deg. C. as rapidly as possible while stirring. Transfer the fatty acids, when cooled somewhat, to a 1-in. by 4-in. titer tube, placed in a 16-oz. salt-mouth bottle of clear glass, fitted with a cork that is perforated so as to hold the tube rigidly when in position. Suspend the titer thermometer so that it can be used as a stirrer and stir the fatty acids slowly (about 100 revolutions per minute) until the mercury remains stationary for 30 seconds. Allow the thermometer to hang quietly with the bulb in the center of the tube and report the highest point to which the mercury rises as the titer of the fatty acids. The titer should be made at about 20deg. C. for all fats having a titer above 30deg. C. and at 10deg. C. below the titer for all other fats. Any convenient means may be used for obtaining a temperature of 10deg. below the titer of the various fats. The committee recommends first of all a chill room for this purpose; second, an artificially chilled small chamber with glass window; third, immersion of the salt-mouth bottle in water or other liquid of the desired temperature.
UNSAPONIFIABLE MATTER.
EXTRACTION CYLINDER--The cylinder shall be glass-stoppered, graduated at 40 cc., 80 cc. and 130 cc., and of the following dimensions: diameter about 1-3/8 in., height about 12 in.
PETROLEUM ETHER--Redistilled petroleum ether, boiling under 75deg. C., shall be used. A blank must be made by evaporating 250 cc. with about 0.25 g. of stearine or other hard fat (previously brought to constant weight by heating) and drying as in the actual determination. The blank must not exceed a few milligrams.
DETERMINATION--Weigh 5 g. (+-0.20 g.) of the prepared sample into a 200-cc. Erlenmeyer flask, add 30 cc. of redistilled 95 per cent (approximately) ethyl alcohol and 5 cc. of 50 per cent aqueous potassium hydroxide, and boil the mixture for one hour under a reflux condenser. Transfer to the extraction cylinder and wash to the 40-cc. mark with redistilled 95 per cent ethyl alcohol. Complete the transfer, first with warm, then with cold water, till the total volume amounts to 80 cc. Cool the cylinder and contents to room temperature and add 50 cc. of petroleum ether. Shake _vigorously_ for one minute and allow to settle until both layers are clear, when the volume of the upper layer should be about 40 cc. Draw off the petroleum ether layer as closely as possible by means of a slender glass siphon into a separatory funnel of 500 cc. capacity. Repeat extraction at least four more times, using 50 cc. of petroleum ether each time. More extractions than five are necessary where the unsaponifiable matter runs high, say over 5 per cent, and also in some cases where it is lower than 5 per cent, but is extracted with difficulty. Wash the combined extracts in a separatory funnel three times with 25-cc. portions of 10 per cent alcohol, shaking vigorously each time. Transfer the petroleum ether extract to a wide-mouth tared flask or beaker, and evaporate the petroleum ether on a steam bath in an air current. Dry as in the method for MOISTURE AND VOLATILE MATTER. Any blank must be deducted from the weight before calculating unsaponifiable matter. Test the final residue for solubility in 50 cc. petroleum ether at room temperature. Filter and wash free from the insoluble residue, if any, evaporate and dry in the same manner as before. The Committee wishes to emphasize the necessity of thorough and vigorous shaking in order to secure accurate results. The two phases must be brought into the most intimate contact possible, otherwise low and disagreeing results may be obtained.
IODINE NUMBER--WIJS METHOD.
PREPARATION OF REAGENTS--_Wijs Iodine Solution_--Dissolve 13.0 g. of resublimed iodine in one liter of C. P. glacial acetic acid and pass in washed and dried chlorine gas until the original thiosulfate titration of the solution is not quite doubled. The solution is then preserved in amber glass-stoppered bottles, sealed with paraffin until ready for use.
Mark the date on which the solution is prepared on the bottle or bottles and do not use Wijs solution which is more than 30 days old.
There should be no more than a slight excess of iodine, and no excess of chlorine. When the solution is made from iodine and chlorine, this point can be ascertained by not quite doubling the titration.[32]
The glacial acetic acid used for preparation of the Wijs solution should be of 99.0 to 99.5 per cent strength. In case of glacial acetic acids of somewhat lower strength, the Committee recommends freezing and centrifuging or draining as a means of purification.
_N_/10 _Sodium Thiosulfate Solution_--Dissolve 24.8 g. of C. P. sodium thiosulfate in recently boiled distilled water and dilute with the same to one liter at the temperature at which the titrations are to be made.
_Starch Paste_--Boil 1 g. of starch in 200 cc. of distilled water for 10 min. and cool to room temperature.
An improved starch solution may be prepared by autoclaving 2 g. of starch and 6 g. of boric acid dissolved in 200 cc. water at 15 lbs. pressure for 15 min. This solution has good keeping qualities.
_Potassium Iodide Solution_--Dissolve 150 g. of potassium iodide in water and make up to one liter.
_N_/10 _Potassium Bichromate_--Dissolve 4.903 g. of C. P. potassium bichromate in water and make the volume up to one liter at the temperature at which titrations are to be made.
The Committee calls attention to the fact that occasionally potassium bichromate is found containing sodium bichromate, although this is of rare occurrence. If the analyst suspects that he is dealing with an impure potassium bichromate, the purity can be ascertained by titration against re-sublimed iodine. However, this is unnecessary in the great majority of cases.
_Standardization of the Sodium Thiosulfate Solution_--Place 40 cc. of the potassium bichromate solution, to which has been added 10 cc. of the solution of potassium iodide, in a glass-stoppered flask. Add to this 5 cc. of strong hydro-chloric acid. Dilute with 100 cc. of water, and allow the _N_/10 sodium thiosulfate to flow slowly into the flask until the yellow color of the liquid has almost disappeared. Add a few drops of the starch paste, and with constant shaking continue to add the _N_/10 sodium thiosulfate solution until the blue color just disappears.
DETERMINATION--Weigh accurately from 0.10 to 0.50 g. (depending on the iodine number) of the melted and filtered sample into a clean, dry, 16-oz. glass-stoppered bottle containing 15-20 cc. of carbon tetrachloride or chloroform. Add 25 cc. of iodine solution from a pipette, allowing to drain for a definite time. The excess of iodine should be from 50 per cent to 60 per cent of the amount added, that is, from 100 per cent to 150 per cent of the amount absorbed. Moisten the stopper with a 15 per cent potassium iodide solution to prevent loss of iodine or chlorine but guard against an amount sufficient to run down inside the bottle. Let the bottle stand in a dark place for 1/2 hr. at a uniform temperature. At the end of that time add 20 cc. of 15 per cent potassium iodide solution and 100 cc. of distilled water. Titrate the iodine with _N_/10 sodium thiosulfate solution which is added gradually, with constant shaking, until the yellow color of the solution has almost disappeared. Add a few drops of starch paste and continue titration until the blue color has entirely disappeared. Toward the end of the reaction stopper the bottle and shake violently so that any iodine remaining in solution in the tetrachloride or chloroform may be taken up by the potassium iodide solution. Conduct two determinations on blanks which must be run in the same manner as the sample except that no fat is used in the blanks. Slight variations in temperature quite appreciably affect the titer of the iodine solution, as acetic acid has a high coefficient of expansion. It is, therefore, essential that the blanks and determinations on the sample be made at the same time. The number of cc. of standard thiosulfate solution required by the blank, less the amount used in the determination, gives the thiosulfate equivalent of the iodine absorbed by the amount of sample used in the determination. Calculate to centigrams of iodine absorbed by 1 g. of sample (= per cent iodine absorbed).
DETERMINATION, TUNG OIL--Tung oil shows an erratic behavior with most iodine reagents and this is particularly noticeable in the case of the Hanus reagent which is entirely unsuitable for determining the iodine number of this oil since extremely high and irregular results are obtained. The Huebl solution shows a progressive absorption up to 24 hrs. and probably for a longer time but the period required is entirely too long for a chemical determination. The Wijs solution gives good results if the following precautions are observed:
Weigh out 0.15 +- 0.05 g., use an excess of 55 +- 3 per cent Wijs solution. Conduct the absorption at a temperature of 20-25deg. C. for 1 hr. In other respects follow the instructions detailed above.
SAPONIFICATION NUMBER (KOETTSTORFER NUMBER).
PREPARATION OF REAGENTS. _N/2 Hydrochloric Acid_--Carefully standardized.
_Alcoholic Potassium Hydroxide Solution_--Dissolve 40 g. of pure potassium hydroxide in one liter of 95 per cent redistilled alcohol (by volume). The alcohol should be redistilled from potassium hydroxide over which it has been standing for some time, or with which it has been boiled for some time, using a reflux condenser. The solution must be clear and the potassium hydroxide free from carbonates.
DETERMINATION--Weigh accurate about 5 g. of the filtered sample into a 250 to 300 cc. Erlenmeyer flask. Pipette 50 cc. of the alcoholic potassium hydroxide solution into the flask, allowing the pipette to drain for a definite time. Connect the flask with an air condenser and boil until the fat is completely saponified (about 30 minutes). Cool and titrate with the _N_/2 hydrochloric acid, using phenolphthalein as an indicator. Calculate the Koettstorfer number (mg. of potassium hydroxide required to saponify 1 g. of fat). Conduct 2 or 3 blank determinations, using the same pipette and draining for the same length of time as above.
MELTING POINT.
APPARATUS--_Capillary tubes_ made from 5 mm. inside diameter thin-walled glass tubing drawn out to 1 mm. inside diameter. Length of capillary part of tubes to be about 5 cm. Length of tube over all 8 cm.
_Standard thermometer_ graduated in tenths of a degree.
_600 cc. beaker._
DETERMINATION--The sample should be clear when melted and entirely free from moisture, or incorrect results will be obtained.
Melt and thoroughly mix the sample. Dip three of the capillary tubes above described in the oil so that the fat in the tube stands about 1 cm. in height. Now fuse the capillary end carefully by means of a small blast flame and allow to cool. These tubes are placed in a refrigerator over night at a temperature of from 40 to 50deg. F. They are then fastened by means of a rubber band or other suitable means to the bulb of a thermometer graduated in tenths of a degree. The thermometer is suspended in a beaker of water (which is agitated by air or other suitable means) so that the bottom of the bulb of the thermometer is immersed to a depth of about 3 cm. The temperature of the water is increased gradually at the rate of about 1deg. per minute.
The point at which the sample becomes opalescent is first noted and the heating continued until the contents of the tube becomes uniformly transparent. The latter temperature is reported as the melting point.
Before finally melting to a perfectly clear fluid, the sample becomes opalescent and usually appears clear at the top, bottom, and sides before becoming clear at the center. The heating is continued until the contents of the tube become uniformly clear and transparent. This temperature is reported as the melting point.[33] It is usually only a fraction of a degree above the opalescent point noted. The thermometer should be read to the nearest 1/2deg. C., and in addition this temperature may be reported to the nearest degree Fahrenheit if desired.
CLOUD TEST.
PRECAUTIONS--(1) The oil must be perfectly dry, because the presence of moisture will produce a turbidity before the clouding point is reached.
(2) The oil must be heated to 150deg. C. over a free flame, immediately before making the test.
(3) There must not be too much discrepancy between the temperature of the bath and the clouding point of the oil. An oil that will cloud at the temperature of hydrant water should be tested in a bath of that temperature. An oil that will cloud in a mixture of ice and water should be tested in such a bath. An oil that will not cloud in a bath of ice and water must be tested in a bath of salt, ice, and water.
DETERMINATION--The oil is heated in a porcelain casserole over a free flame to 150deg. C., stirring with the thermometer. As soon as it can be done with safety, the oil is transferred to a 4 oz. oil bottle, which must be perfectly dry. One and one-half ounces of the oil are sufficient for the test. A dry centigrade thermometer is placed in the oil, and the bottle is then cooled by immersion in a suitable bath. The oil is constantly stirred with the thermometer, taking care not to remove the thermometer from the oil at any time during the test, so as to avoid stirring air bubbles into the oil. The bottle is frequently removed from the bath for a few moments. The oil must not be allowed to chill on the sides and bottom of the bottle. This is effected by constant and vigorous stirring with the thermometer. As soon as the first permanent cloud shows in the body of the oil, the temperature at which this cloud occurs is noted.
With care, results concordant to within 1/2deg. C. can be obtained by this method. A Fahrenheit thermometer is sometimes used because it has become customary to report results in degrees Fahrenheit.
The oil must be tested within a short time after heating to 150deg. C. and a re-test must always be preceded by reheating to that temperature. The cloud point should be approached as quickly as possible, yet not so fast that the oil is frozen on the sides or bottom of the bottle before the cloud test is reached.
Notes on the Above Methods.
SAMPLING.
The standard size of sample adopted by the committee is at least 3 lbs. in weight. The committee realizes that this amount is larger than any samples usually furnished even when representing shipments of from 20,000 to 60,000 lbs. but it believes that the requirement of a larger sample is desirable and will work toward uniform and more concordant results in analysis. It will probably continue to be the custom of the trade to submit smaller buyers' samples than required by the committee, but these are to be considered only as samples for inspection and not for analysis. The standard analytical sample must consist of 3 lbs. or more.
The reasons for keeping samples in a dark, cool place are obvious. This is to prevent any increase in rancidity and any undue increase in free fatty acids. In the case of many fats the committee has found in its co-operative analytical work that free acid tends to increase very rapidly. This tendency is minimized by low temperatures.
MOISTURE AND VOLATILE MATTER.
After careful consideration the committee has decided that moisture is best determined in a vacuum oven of the design which accompanies the above report. Numerous results on check samples have confirmed the committee's conclusions. The oven recommended by the committee is constructed on the basis of well-known principles and it is hoped that this type will be adopted generally by chemists who are called upon to analyze fats and oils. The experiments of the committee indicate that it is a most difficult matter to design a vacuum oven which will produce uniform temperatures throughout; and one of the principal ideas in the design adopted is uniformity of temperature over the entire single shelf. This idea has not quite been realized in practice but, nevertheless, the present design approaches much closer to the ideal than other vacuum ovens commonly used. In the drawing the essential dimensions are those between the heating units and the shelf and the length and breadth of the outer casting. The standard Fat Analysis Committee Oven (F. A. C. Oven) can be furnished by Messrs. E. H. Sargent & Company, 125 West Lake street, Chicago.
The committee realizes that for routine work a quicker method is desirable and has added one such method and has also stated the conditions under which comparable results can be obtained by means of the ordinary well-ventilated air oven held at 105 to 110deg. C. However, in accordance with a fundamental principle adopted by the committee at its first meeting, only one standard method is adopted and declared official for each determination.
The committee realizes that in the case of all methods for determining moisture by means of loss on heating there may be a loss due to volatile matter (especially fatty acids) other than water. The title of the determination MOISTURE AND VOLATILE MATTER indicates this idea, but any considerable error from this source may occur only in the case of high acid fats and oils and particularly those containing lower fatty acids such as coconut and palm kernel oil. In the case of extracted greases which have not been properly purified, some of the solvent may also be included in the moisture and volatile matter determination, but inasmuch as the solvent, usually a petroleum product, can only be considered as foreign matter, for commercial purposes, it is entirely proper to include it with the moisture.
The committee has also considered the various distillation methods for the determination of moisture in fats and oils, but since according to the fundamental principles which it was endeavoring to follow it could only standardize one method, it was decided that the most desirable one on the whole was the vacuum-oven method as given. There are cases wherein a chemist may find it desirable to check a moisture determination or investigate the moisture content of a fat or oil further by means of one of the distillation methods.
However, in co-operative work the distillation method in various types of apparatus has not yielded satisfactory results. The difficulties appear to be connected with a proper choice of solvent and particularly with the tendency of drops of water to adhere to various parts of the glass apparatus instead of passing on to the measuring device. When working on coconut oil containing a high percentage of free fatty acids, concordant results could not be obtained by the various members of the committee when working with identical samples, solvents and apparatus.
On the other hand, the committee found by individual work, co-operative work and collaborative work by several members of the committee in one laboratory, that the old, well-known direct heating method (which the committee has designated the hot plate method) yielded very satisfactory results on all sorts of fats and oils including emulsions such as butter and oleomargarine and even on coconut oil samples containing 15 to 20 per cent free fatty acids and 5 to 6 per cent of moisture. Unfortunately, this method depends altogether on the operator's skill and while the method may be taught to any person whether a chemist or not so that he can obtain excellent results with it, it is difficult to give a sufficiently, complete description of it so that any chemist anywhere after reading the description could follow it successfully. The method is undoubtedly worthy of much confidence in careful hands. It is quick, accurate and reliable. It is probably the best single method for the determination of moisture in all sorts of samples for routine laboratory work. On account of this fact the committee desires to announce its willingness to instruct any person in the proper use of the method who desires to become acquainted with it and who will visit any committee member's laboratory.
INSOLUBLE IMPURITIES.
This determination, the title for which was adopted after careful consideration, determines the impurities which have generally been known as dirt, suspended matter, suspended solids, foreign solids, foreign matter, etc., in the past. The first solvent recommended by the committee is hot kerosene to be followed by petroleum ether kept at ordinary room temperature. Petroleum ether, cold or only slightly warm, is not a good fat and metallic soap solvent, whereas hot kerosene dissolves these substances readily, and for this reason the committee has recommended the double solvent method so as to exclude metallic soaps which are determined below as soluble mineral matter.
SOLUBLE MINERAL MATTER.
Soluble mineral matter represents mineral matter combined with fatty acids in the form of soaps in solution in the fat or oil. Formerly, this mineral matter was often determined in combination by weighing the separated metallic soap or by weighing it in conjunction with the insoluble impurities. Since the soaps present consist mostly of lime soap, it has been customary to calculate the lime present therein by taking 0.1 the weight of the total metallic soaps. The standard method as given above is direct and involves no calculation. The routine method given in the note has been placed among the methods for the reason that it is used in some laboratories, but has not been adopted as a standard method in view of the fact that the committee has made it a rule to adopt only one standard method. It should be pointed out, however, that the method cannot be considered accurate for the reason that insoluble impurities may vary from sample to sample to a considerable extent and the error due to the presence of large particles of insoluble impurities is thus transferred to the soluble mineral matter. The committee has found one type of grease (naphtha bone grease) which shows most unusual characteristics. The type sample contains 4.3 per cent soluble mineral matter by the committee method which would be equivalent to 43.0 per cent free fatty acid. The kerosene and gasoline filtrate was
## particularly clear, nevertheless the ash was found to contain 36.43 per
cent P_{2}O_{5} equivalent to 79.60 per cent of Ca_{3}(PO_{4})_{2} and 9.63 per cent of Fe_{2}O_{3}. The method, therefore, determines the soluble mineral matter in this case satisfactorily but the factor 10 is not applicable for calculating the fatty acids combined therewith. It is necessary, therefore, in order to determine the fatty acids combined with soluble mineral matter in the original sample to determine the actual bases in the soluble mineral matter as obtained by ashing the kerosene and gasoline filtrate. To the bases so determined the factor 10 can then be applied.
FREE FATTY ACID.
The fatty acid method adopted is sufficiently accurate for commercial purposes. In many routine laboratories the fat or oil is measured and not weighed, but the committee recommends weighing the sample in all cases. For scientific purposes the result is often expressed as "acid number," meaning the number of milligrams of KOH required to neutralize the free acids in one gram of fat, but the commercial practice has been, and is, to express the fatty acids as oleic acid or in the case of palm oil, as palmitic acid, in some instances. The committee sees no objection to the continuation of this custom so long as the analytical report clearly indicates how the free acid is expressed. For a more exact expression of the free acid in a given fat, the committee recommends that the ratio of acid number to saponification number be used. This method of expressing results is subject to error when unsaponifiable fatty matter is present, since the result expresses the ratio of free fatty acid to total saponifiable fatty matter present.
TITER.
At the present time the prices of glycerol and caustic potash are abnormally high, but the committee has considered that the methods adopted are for normal times and normal prices. For routine work during the period of high prices the following method may be used for preparing the fatty acids and is recommended by the committee:
Fifty grams of fat are saponified with 60 cc. of a solution of 2 parts of methyl alcohol to 1 of 50 per cent NaOH. The soap is dried, pulverized and dissolved in 1000 cc. of water in a porcelain dish and then decomposed with 25 cc. of 75 per cent sulphuric acid. The fatty acids are boiled until clear oil is formed and then collected and settled in a 150-cc. beaker and filtered into a 50-cc. beaker. They are then heated to 130deg. C. as rapidly as possible with stirring, and transferred, after they have cooled somewhat, to the usual 1-in. by 4-in. titer tube.
The method of taking the titer, including handling the thermometer, to be followed is the same as that described in the standard method. Even at present high prices many laboratories are using the glycerol-caustic potash method for preparing the fatty acids, figuring that the saving of time more than compensates for the extra cost of the reagents. Caustic soda cannot be substituted for caustic potash in the glycerol method.
UNSAPONIFIABLE MATTER.
The committee has considered unsaponifiable matter to include those substances frequently found dissolved in fats and oils which are not saponified by the caustic alkalies and which at the same time are soluble in the ordinary fat solvents. The term includes such substances as the higher alcohols, such as cholesterol which is found in animal fats, phytosterol found in some vegetable fats, paraffin and petroleum oils, etc. UNSAPONIFIABLE MATTER should not be confused in the lay mind with INSOLUBLE IMPURITIES OR SOLUBLE MINERAL MATTER.
The method adopted by the committee has been selected only after the most careful consideration of other methods, such as the dry extraction method and the wet method making use of the separatory funnel. At first consideration the dry extraction process would seem to offer the best basis for an unsaponifiable matter method, but in practice it has been found absolutely impossible for different analysts to obtain agreeing results when using any of the dry extraction methods proposed. Therefore, this method had to be abandoned after numerous trials, although several members of the committee strongly favored it in the beginning.
IODINE NUMBER--The iodine number adopted by the committee is that determined by the well-known Wijs method. This method was adopted after careful comparison with the Hanus and Huebl methods. The Huebl method was eliminated from consideration almost at the beginning of the committee's work for the reason that the time required for complete absorption of the iodine is unnecessarily long and, in fact, even after absorption has gone on over night, it is apparently not complete. In the case of the Hanus and Wijs methods complete absorption takes place in from 15 minutes to an hour, depending on conditions. Formerly, many chemists thought the Hanus solution rather easier to prepare than the Wijs solution, but the experience of the committee was that the Wijs solution was no more difficult to prepare than the Hanus. Furthermore, absorption of iodine from the Wijs solution appeared to take place with greater promptness and certainty than from the Hanus and was complete in a shorter time. Results by the Wijs method were also in better agreement in the case of oils showing high iodine absorption than with the Hanus solution and showed a slightly higher iodine absorption for the same length of time. However, the difference was not great. The committee investigated the question of substitution since it has been suggested that in case of the Wijs solution substitution of iodine in the organic molecule might occur, and found no evidence of this in the time required for the determination, namely, 1/2 hr., or even for a somewhat longer period. One member of the committee felt that it was not desirable to introduce the Wijs method into these standard methods since the Hanus method was already standardized by the Association of Official Agricultural Chemists, but the committee felt that it must follow the principle established at the commencement of its work, namely, that of adopting the method which appeared to be the best from all standpoints, taking into consideration accuracy, convenience, simplicity, time, expense, etc., without allowing precedent to have the deciding vote.
IODINE NUMBER, TUNG OIL--The committee has made an extensive study of the application of the Wijs method to the determination of iodine value in the case of tung oil with the result that it recommends the method for this oil but has thought it desirable to limit the conditions under which the determination is conducted rather narrowly, although reasonably good results are obtained by the committee method without making use of the special limitations.
The co-operative work of the committee and the special investigations conducted by individual members bring out the following points:
_Influence of Temperature_--From 16deg. C. to 30deg. C. there is a moderate increase in the absorption, but above 30deg. the increase is rather rapid so that it was thought best to limit the temperature in the case of tung oil to 20deg. to 25deg. C.
_Influence of Time_--The absorption increases with the time but apparently complete absorption, so far as unsaturated bonds are concerned, occurs well within one hour's time. Consequently, one hour was set as the practical limit.
_Influence of Excess_--The excess of iodine solution also tends to increase the iodine number, hence the Committee thought it necessary to limit the excess rather rigidly to 55 +- 3 per cent, although with greater latitude results were reasonably good.
_Influence of Age of Solution_--Old solutions tend to give low results although up to 2 mo. no great differences were observed. Nevertheless, it was thought best to limit the age of the solution to 30 days--long enough for all practical purposes.
_Amount of Sample_--As a practical amount of sample to be weighed out the Committee decided on 0.15 g. with a tolerance of 0.05 g. in either direction according to preference. In other words, the amount of sample to be taken for the determination to be from 0.1 to 0.2 g. in the discretion of the analyst.
The Committee's study of the Huebl method which has been adopted by the Society for Testing Materials in the case of tung oil indicates that this method when applied to tung oil is subject to the same influences as the Wijs method and it has the additional very serious disadvantage of requiring a long period of time for absorption which cannot be considered reasonable for a modern analytical method. When using the Huebl solution, the absorption is not complete in the case of tung oil at 3, 7, 18 or even 24 hrs.
The Hanus method in the case of tung oil gives very high and erratic results, as high as 180 to 240 in ordinary cases for an oil whose true iodine number is about 165.
MELTING POINT.
A melting point is the temperature at which a solid substance assumes the liquid condition. If the solid is a pure substance in the crystalline condition the melting point is sharp and well defined for any given pressure. With increased pressure the melting point is lowered or raised, depending on whether the substance contracts or expands in melting. The lowering or raising of the melting point with pressure is very slight and ordinarily is not taken into consideration. Melting-point determinations are commonly carried out under ordinary atmospheric pressures without correction. The general effect of soluble impurities is to lower the melting point, and this holds true whether the impurity has a higher or lower melting point than the pure substance (solvent). Thus if a small amount of stearic acid be added to liquid palmitic acid and the solution frozen, the melting point of this solid will be lower than that of palmitic acid. Likewise the melting point of stearic acid is lowered by the addition of a small amount of palmitic acid. A eutectic mixture results when two components solidify simultaneously at a definite temperature. Such a mixture has a constant melting point and because of this and also because both solid and liquid phases have the same composition, eutectic mixtures were formerly looked upon as compounds. The phenomenon of double melting points has been observed in the case of a number of glycerides. Such a glyceride when placed in the usual capillary tube and subjected to increasing temperature quickly resolidifies only to melt again and remain melted at a still higher temperature. This phenomenon has not yet been sufficiently investigated to afford a satisfactory explanation.
Non-crystalline substances such as glass, sealing wax and various other waxes and wax mixtures, and most colloidal substances do not exhibit a sharp melting point, but under the application of heat first soften very gradually and at a considerably higher temperature melt sufficiently to flow. This phenomenon of melting through a long range of temperature may be due to the amorphous nature of the substance or to the fact that it consists of a very large number of components of many different melting points.
The fats and oils of natural origin, that is, the animal and vegetable fats and oils, consist of mixtures of glycerides and, generally speaking, of a considerable number of such components. These components are crystalline and when separated in the pure state have definite melting points, although some exhibit the phenomenon of double melting point. For the most part the naturally occurring glycerides are mixed glycerides. In the natural fats and oils there are present also certain higher alcohols, of which cholesterol is characteristic of the animal fats and oils and phytosterol of many of the vegetable fats and oils. In addition to the crystalline glycerides and the higher alcohols present in neutral fats, there are in fats of lower grade, fatty acids, which are crystalline, and also various non-crystalline impurities of an unsaponifiable nature, and the presence of these impurities tends to lower the melting point. They also tend to induce undercooling and when the liquid fat or oil is being chilled for purposes of solidification or in determination of titer.
The presence of water, especially when this is thoroughly mixed or emulsified with a fat or oil, also influences the melting point to a marked extent, causing the mixture to melt through a longer range of temperatures than would be the case if the water were absent. This is
## particularly true of emulsified fats and oils, such as butter and
oleomargarine, both of which contain, besides water, the solids naturally present in milk or cream and including casein, milk sugar, and salts. The melting-point method recommended by the Committee is not applicable to such emulsions or other watery mixtures and the Committee has found it impossible to devise an accurate method for making softening-point or melting-point determinations on products of this nature. Not only the amount of water present but also the fineness of its particles, that is, its state of subdivision and distribution, in a fat or oil influences the softening point or melting point and causes it to vary widely in different samples.
As a consequence of the foregoing facts, natural fats and oils do not exhibit a definite melting point, composed as they are of mixtures of various crystalline glycerides, higher alcohols, fatty acids, and non-crystalline substances. Therefore, the term melting point when applied to them requires further definition. They exhibit first a lower melting point (the melting point of the lowest melting component) or what might be called the softening point and following this the fat softens through a shorter or longer range of temperature to the final melting point at which temperature the fat is entirely liquid. This is the melting point determined by the Committee's melting-point method. The range between the softening point and the final melting point varies greatly with the different fats and oils depending on their chemical components, the water associated with them, emulsification, etc. In the case of coconut oil the range between softening point and final melting point is rather short; in the case of butter, long. Various methods have been devised to determine the so-called melting point of fats and oils. Most of these methods, however, determine, not the melting point, but the softening point or the flow point of the fat and the great difficulty has been in the past to devise a method which would determine even this point with reasonable accuracy and so that results could be easily duplicated. It has been the aim of the Committee to devise a simple method for the determination of the melting point of fats and oils, but it should be understood that the term melting point in the scientific sense is not applicable to natural fats and oils.
FOOTNOTES:
[22] Approved by the Supervisory Committee on Standard Methods of Analysis of the American Chemical Society.
[23] Live steam must not be turned into tank cars or coils before samples are drawn, since there is no certain way of telling when coils are free from leaks.
[24] If there is water present under the solid material this must be noted and estimated separately.
[25] Boiling point of water at reduced pressures.
Pressure Boiling Point Boiling Point Boiling Point Mm. Hg. to 1deg. C. +15deg. C. +20deg. C. 100 52deg. C. 67deg. C. 72deg. C. 90 50 65 70 80 47 62 67 70 45 60 65 60 42 57 62 50 38 53 58 40 34 49 54
[26] Results comparable to those of the Standard Method may be obtained on most fats and oils by drying 5-g. portions of the sample, prepared and weighed as above, to constant weight in a well-constructed and well-ventilated air oven held uniformly at a temperature of 105deg. to 110deg. C. The thermometer bulb should be close to the sample. The definition of constant weight is the same as for the Standard Method.
[27] The following method is suggested by the Committee for routine control work: Weigh out 5- to 25-g. portions of prepared sample into a glass or aluminum (_Caution_: Aluminum soap may be formed) beaker or casserole and heat on a heavy asbestos board over burner or hot plate, taking care that the temperature of the sample does not go above 130deg. C. at any time. During the heating rotate the vessel gently on the board by hand to avoid sputtering or too rapid evolution of moisture. The proper length of time of heating is judged by absence of rising bubbles of steam, by the absence of foam or by other signs known to the operator. Avoid overheating of sample as indicated by smoking or darkening. Cool in desiccator and weigh.
By co-operative work in several laboratories, the Committee has demonstrated that this method can be used and satisfactory results obtained on coconut oil even when a considerable percentage of free fatty acids is present, and the method is recommended for this purpose. Unfortunately on account of the very great personal factor involved, the Committee cannot establish this method as a preferred method. Nevertheless, after an operator has learned the technique of the method, it gives perfectly satisfactory results for ordinary oils and fats, butter, oleomargarine and coconut oil, and deserves more recognition than it has heretofore received.
[28] For routine control work, filter paper is sometimes more convenient than the prepared Gooch crucible, but must be very carefully washed, especially around the rim, to remove the last traces of fat.
[29] For routine work, an ash may be run on the original fat, and the soluble mineral matter obtained by deducting the ash on the insoluble impurities from this. In this case the Gooch crucible should be prepared with an ignited asbestos mat so that the impurities may be ashed directly after being weighed. In all cases ignition should be to constant weight so as to insure complete decomposition of carbonates.
[30] See note on Soluble Mineral Matter following these methods. When the ash contains phosphates the factor 10 cannot be applied, but the bases consisting of calcium oxide, etc., must be determined, and the factor 10 applied to them.
[31] For routine work methyl or denatured ethyl alcohol of approximately 95 per cent strength may be used. With these reagents the end-point is not sharp.
[32] P. C. McIlhiney, _J. Am. Chem. Soc._, 29 (1917), 1222, gives the following details for the preparation of the iodine monochloride solution:
The preparation of the iodine monochloride solution presents no great difficulty, but it must be done with care and accuracy in order to obtain satisfactory results. There must be in the solution no sensible excess either of iodine or more particularly of chlorine, over that required to form the monochloride. This condition is most satisfactorily attained by dissolving in the whole of the acetic acid to be used the requisite quantity of iodine, using a gentle heat to assist the solution, if it is found necessary, setting aside a small portion of this solution, while pure and dry chlorine is passed into the remainder until the halogen content of the whole solution is doubled. Ordinarily it will be found that by passing the chlorine into the main part of the solution until the characteristic color of free iodine has just been discharged there will be a slight excess of chlorine which is corrected by the addition of the requisite amount of the unchlorinated portion until all free chlorine has been destroyed. A slight excess of iodine does little or no harm, but excess of chlorine must be avoided.
[33] The melting point of oils may be determined in general according to the above procedure, taking into consideration the lower temperature required.
PLANT AND MACHINERY
Illustrations of machinery and layouts of the plant of a modern soap-making establishment.
[Illustration: HOIST, LYE TANK, ETC.]
[Illustration: MELTING-OUT TROUGH]
[Illustration: LAUNDRY SOAP PLANT]
[Illustration: DRYING RACK]
[Illustration: SOAP KETTLE]
[Illustration: REMELTER]
[Illustration: CRUTCHER (Cross Section)]
[Illustration: HORIZONTAL CRUTCHER]
[Illustration: CRUTCHER]
[Illustration: WRAPPING MACHINE (LAUNDRY SOAP)]
[Illustration: SLABBER]
[Illustration: CUTTING TABLE]
[Illustration: AUTOMATIC POWER CUTTING TABLE]
[Illustration: AUTOMATIC PRESS (LAUNDRY)]
[Illustration: CUTTING TABLE (HAND)]
[Illustration: CARTON WRAPPING MACHINE]
[Illustration: DRYING RACKS]
[Illustration: SOAP POWDER BOX]
[Illustration: SCOURING SOAP PRESS]
[Illustration: FRAME]
[Illustration: SOAP POWDER EQUIPMENT]
[Illustration: FLUFFY SOAP POWDER EQUIPMENT]
[Illustration: SOAP POWDER MIXER]
[Illustration: SOAP POWDER MILL]
[Illustration: TOILET SOAP EQUIPMENT]
[Illustration: TOILET SOAP DRYER]
[Illustration: MILLING BOX]
[Illustration: AMALGAMATOR]
[Illustration: TOILET SOAP MILL]
[Illustration: TOILET SOAP MILL]
[Illustration: CHIPPER]
[Illustration: PLODDER]
[Illustration: HORIZONTAL CHIPPER]
[Illustration: AMALGAMATOR (IMPROVED)]
[Illustration: PRESS (LETTERING ON 4 SIDES OF CAKE)]
[Illustration: Press (Foot)]
[Illustration: Press (Foot)]
[Illustration: PLODDER]
[Illustration: AUTOMATIC PRESS (TOILET)]
[Illustration: MULTIPLE CAKE CUTTER]
[Illustration: CAKE CUTTER]
[Illustration: CHIPPER]
[Illustration: GLYCERINE DISTILLING PLANT]
[Illustration: CRUDE GLYCERINE PLANT]
[Illustration: H-A FATTY ACID DISTILLING PLANT]
Appendix
Tables marked * are taken from the German Year Book for Soap Industry.
(U. S. BUREAU OF STANDARDS)
THE METRIC SYSTEM.
The fundamental unit of the metric system is the meter (the unit of length). From this the units of mass (gram) and capacity (liter) are derived. All other units are the decimal sub-divisions or multiples of these. These three units are simply related, so that for all practical purposes the volume of one kilogram of water (one liter) is equal to one cubic decimeter.
============================================================ | Prefixes. Meaning. | Units. ________________________________________|___________________ | Milli- = one thousandth 1-1000 .001 | Centi- = one hundredth 1-100 .01 | Meter for length. Deci- = one tenth 1-10 .1 | Unit = one 1. | Gram for mass. Deka- = ten 10-1 10. | Hecto- = one hundred 100-1 100. | Liter for capacity. Kilo- = one thousand 1000-1 1000. | ============================================================
The metric terms are formed by combining the words "Meter," "Gram" and "Liter" with the six numerical prefixes.
LENGTH
10 milli-meters mm = 1 centi-meter c m
10 centi-meters = 1 deci-meter d m
10 deci-meters = 1 meter (about 40 inches) m
10 meters = 1 deka-meter d k m
10 deka-meters = 1 hecto-meter h m
10 hecto-meters = 1 kilo-meter (about 5/8 mile) k m
MASS.
10 milli-grams. m g = 1 centi-gram c g 10 centi-grams = 1 deci-gram d g 10 deci-grams = 1 gram (about 15 grains) g 10 grams = 1 deka-gram d k g 10 Deka-grams = 1 hecto-gram h g 10 hecto-grams = 1 kilo-gram (about 2 pounds) k g
CAPACITY.
10 milli-liters. m l = 1 centi-liter c l 10 centi-liters = 1 deci-liter d l 10 deci-liters = 1 liter (about 1 quart) l 10 liters = 1 deka-liter d k l 10 deka-liters = 1 hecto-liter (about a barrel) h l 10 hecto-liters = 1 kilo-liter k l
The square and cubic units are the squares and cubes of the linear units.
The ordinary unit of land area is the Hectare (about 2-1/2 acres).
U.S. BUREAU OF STANDARDS TABLE OF METRIC EQUIVALENTS
Meter = 39.37 inches.
Legal Equivalent Adopted by Act of Congress July 28, 1866.
LENGTH.
Centimeter = 0.3937 inch Meter = 3.28 feet Meter = 1.094 yards Kilometer = 0.621 statute mile Kilometer = 0.5396 nautical mile Inch = 2.540 centimeters Foot = 0.305 meter Yard = 0.914 meter Statute mile = 1.61 kilometers Nautical mile = 1.853 kilometers
AREA.
Sq. centimeter = 0.155 sq. inch Sq. meter = 10.76 sq. feet Sq. meter = 1.196 sq. yards Hectare = 2.47 acres Sq. kilometer = 0.386 sq. mile Sq. inch = 6.45 sq. centimeters Sq. foot = 0.0929 sq. meter Sq. yard = 0.836 sq. meter Acre = 0.405 hectare Sq. mile = 2.59 sq. kilometers
WEIGHT.
Gram = 15.43 grains Gram = 0.772 U. S. apoth. scruple Gram = 0.2572 U. S. apoth. dram Gram = 0.0353 avoir. ounce Gram = 0.03215 troy ounce Kilogram = 2.205 avoir. pounds Kilogram = 2.679 troy pounds Metric ton = 0.984 gross or long ton Metric ton = 1.102 short or net tons Grain = 0.064 gram U. S. apoth. scruple = 1.296 grams U. S. apoth. dram = 3.89 grams Avoir. ounce = 28.35 grams Troy ounce = 31.10 grams Avoir. pound = 0.4536 kilogram Troy pound = 0.373 kilogram Gross or long ton = 1.016 metric tons Short or net ton = 0.907 metric ton
VOLUME.
Cu. centimeter = 0.0610 cu. inch Cu. meter = 35.3 cu. feet Cu. meter = 1.308 cu. yards Cu. inch = 16.39 cu. centimeters Cu. foot = 0.283 cu. meter Cu. yard = 0.765 cu. meter
CAPACITY.
Millimeter = 0.0338 U. S. liq. ounce Millimeter = 0.2705 U. S. apoth. dram Liter = 1.057 U. S. liq. quarts Liter = 0.2642 U. S. liq. gallon Liter = 0.908 U. S. dry quart Dekaliter = 1.135 U. S. pecks Hectoliter = 2.838 U. S. bushels U. S. liq. ounce = 29.57 millimeters U. S. apoth. dram = 3.70 millimeters U. S. liq. quarts = 0.946 liter U. S. dry quarts = 1.101 liters U. S. liq. gallon = 3.785 liters U. S. peck = 0.881 dekaliter U. S. bushel = 0.3524 hectoliter
AVOIRDUPOIS WEIGHT.
1 pound = 16 ounces = 256 drams 1 ounce = 16 "
TROY (APOTHECARIES') WEIGHT (U. S.)
1 pound = 12 ounces = 96 drams = 288 scruples = 5,760 grains 1 ounce = 8 drams = 24 scruples = 480 grains 1 dram = 3 scruples = 60 grains 1 scruple = 20 grains
WINE (APOTHECARIES) LIQUID MEASURE (U. S.)
1 gallon = 8 pints = 128 fl. ozs. = 1,024 fl. drams = 61,440 minims 1 pint = 16 fl. ozs. = 128 fl. drams = 7,689 minims 1 fl. oz. = 8 fl. drams = 480 minims 1 fl. dram = 60 minims
_To find diameter of a circle_ multiply circumference by .31831.
_To find circumference of a circle_, multiply diameter by 3.1416.
_To find area of a circle_, multiply square of diameter by .7854.
_To find surface of a ball_, multiply square of diameter by 3.1416.
_To find side of an equal square_, multiply diameter by .8862.
_To find cubic inches in a ball_, multiply cube of diameter by .5236.
_Doubling the diameter of a pipe_, increases its capacity four times.
_One cubic foot of anthracite coal_ weighs about 53 lbs.
_One cubic foot of bituminous coal_ weighs from 47 to 50 pounds.
_A gallon of water_ (U. S. standard) weighs 8-1/3 pounds and contains 231 cubic inches.
_A cubic foot of water_ contains 7-1/2 gallons, 1728 cubic inches and weighs 62-1/2 pounds.
_To find the number of pounds of water a cylindrical_ tank contains, square the diameter, multiply by .785 and then by the height in feet. This gives the number of cubic feet which multiplied by 62-1/2 gives the capacity in pounds of water. Divide by 7-1/2 and this gives the capacity in gallons.
_A horse-power_ is equivalent to raising 33,000 pounds 1 foot per minute, or 550 pounds 1 foot per second.
_The friction of water in pipes_ is as the square of velocity. The capacity of pipes is as the square of their diameters; thus, doubling the diameter of a pipe increases its capacity four times.
_To find the diameter of a pump cylinder_ to move a given quantity of water per minute (100 feet of piston being the standard of speed), divide the number of gallons by 4, then extract the square root, and the product will be the diameter in inches of the pump cylinder.
_To find the horse-power necessary to elevate water_ to a given height, multiply the weight of the water elevated per minute in pounds by the height in feet, and divide the product by 33,000 (an allowance should be added for water friction, and a further allowance for loss in steam cylinder, say from 20 to 30 per cent).
_To compute the capacity of pumping engines_, multiply the area of water piston, in inches, by the distance it travels, in inches, in a given time. Deduct 3 per cent for slip and rod displacement. The product divided by 231 gives the number of gallons in time named.
_To find the velocity in feet per minute_ necessary to discharge a given volume of water in a given time, multiply the number of cubic feet of water by 144 and divide the product by the area of the pipe in inches.
_To find the area of a required pipe_, the volume and velocity of water being given, multiply the number of cubic feet of water by 144 and divide the product by the velocity in feet per minute. The area being found, the diameter can be learned by using any table giving the "area of circles" and finding the nearest area, opposite to which will be found the diameter to correspond.
Physical and Chemical Constants of Fixed Oils and Fats.
(FROM LEWKOWITSCH AND OTHER AUTHORITIES.)
______________________________________________________________________________ | |Specific | | | | Specific |gravity | Melting- |Solidifying- | | gravity | at | point. | point. | | at 15deg.C.|100deg.C. | deg. C. | deg. C. | _______________________|____________|__________|_____________|_______________| | | | | | Linseed oil | 0.931-0.938| 0.880 | -16 to -26 | -16 | Hemp-seed oil | 0.925-0.931| | | -27 | Walnut oil | 0.925-0.926| 0.871 | | -27 | Poppy-seed oil | 0.924-0.927| 0.873 | | -18 | Sunflower oil | 0.924-0.926| 0.919 | | -17 | Fir-seed oil | 0.925-0.928| | | -27 to -30 | Maize oil | 0.921-0.926| | | -10 to -15 | Cotton-seed oil | 0.922-0.930| 0.867 | | 12 | Sesame oil | 0.923-0.924| 0.871 | | -5 | Rape-seed oil | 0.914-0.917| 0.863 | | -2 to -10 | Black mustard oil | 0.916-0.920| | | -17.5 | Croton oil | 0.942-0.955| | | -16 | Castor oil | 0.960-0.966| 0.910 | | -12 to -18 | Apricot-kernel oil | 0.915-0.919| | | -14 | Almond oil | | 0.915-0.920| | | -10 to -20 | Peanut (arachis) oil | 0.916-0.920| 0.867 | | -3 to -7 | Olive oil | 0.914-0.917| 0.862 | | 2 | Menhaden oil | 0.927-0.933| | | -4 | Cod-liver oil | 0.922-0.927| 0.874 | | 0 to -10 | Seal oil | 0.924-0.929| 0.873 | | 3 | Whale oil | 0.920-0.930| 0.872 | | -2 | Dolphin oil | 0.917-0.918| | | 5 to -3 | Porpoise oil | 0.926 | 0.871 | | -16 | Neat's-foot oil | 0.914-0.916| 0.861 | | 0 to 1.5 | Cotton-seed stearine | 0.919-0.923| 0.867 | 40 | 31 to 32.5 | Palm oil | 0.921-0.925| 0.856 | 27 to 42 | | Cacao butter | 0.950-0.952| 0.858 | 30 to 33 | 25 to 26 | Cocoa-nut oil | 0.925-0.926| 0.873 | 20 to 26 | 16 to 20 | Myrtle wax | 0.995 | 0.875 | 40 to 44 | 39 to 43 | Japan wax | 0.970-0.980| 0.875 | 51 to 54.5 | 46 | Lard | 0.931-0.938| 0.861 | 41 to 46 | 29 | Bone fat | 0.914-0.916| | 21 to 22 | 15 to 17 | Tallow | 0.943-0.952| 0.860 | 42 to 46 | 35 to 37 | Butter fat | 0.927-0.936| 0.866 | 29.5 to 33 | 19 to 20 | Oleomargarine | 0.924-0.930| 0.859 | | | Sperm oil | 0.875-0.884| 0.833 | | -25 | Bottle-nose oil | 0.879-0.880| 0.827 | | | Carnauba wax | 0.990-0.999| 0.842 | 84 to 85 | 80 to 81 | Wool-fat | 0.973 | 0.901 | 39 to 42 | 30 to 30.2 | Beeswax | 0.958-0.969| 0.822 | 62 to 64 | 60.5 to 62 | Spermaceti | 0.960 | 0.812 | 43.5 to 49 | 43.4 to 44.2 | Chinese wax | 0.970 | 0.810 | 80.5 to 81 | 80.5 to 81 | Tung (Chinese wood oil)| 0.936-0.942| | | below -17 | Soya-bean oil | 0.924-0.927| | | 8 to 15 | _______________________|____________|__________|_____________|_______________|
Physical and Chemical Constants of Fixed Oils and Fats.
(FROM LEWKOWITSCH AND OTHER AUTHORITIES.)
Column Headings: A: Saponification value. B: Maumene test. (deg.) C: Iodine value. D: Hehner value. E: Reichert value.
____________________________________________________________________________ | | | | | | | [A] | [B] | [C] | [D] | [E] | ___________________|_____________|___________|____________|_________|______| | | | | | | Linseed oil | 190-195 | 104-111 | 175-190 | | | Hemp-seed oil | 190-193 | 95-96 | 148 | | | Walnut oil | 195 | 96-101 | 144-147 | | | Poppy-seed oil | 195 | 86-88 | 134-141 | 95.38 | | Sunflower oil | 193-194 | 72-75 | 120-129 | 95 | | Fir-seed oil | 191.3 | 98-99 | 118.9-120 | | | Maize oil | 188-193 | 56-60.5 | 117-125 | 89-95.7 | 2.5 | Cotton-seed oil | 191-195 | 68-77 | 104-110 | 96-17 | | Sesame oil | 189-193 | 64-68 | 105-109 | 95.8 | 0.35 | Rape-seed oil | 170-178 | 51-60 | 95-105 | 95 | | Black mustard oil | 174-174.6 | 43-44 | 96-110 | 95.05 | | Croton oil | 210.3-215 | | 101.7-104 | 89 | 13.5 | Castor oil | 178-186 | 46-47 | 83.4-85.9 | | 1.4 | Apricot-kernel oil | 192.2-193.1 | 42.5-46 | 100-107 | | | Almond oil | 190.5-195.4 | 51-54 | 93-97 | 96.2 | | Peanut (arachis) | | | | | | oil | 190-197 | 45-49 | 85-98 | 95.86 | | Olive oil | 191-196 | 41.5-45.5 | 80.6-84.5 | 95.43 | 0.3 | Menhaden oil | 189.3-192 | 123-128 | 140-170 | | 1.2 | Cod-liver oil | 182-187 | 102-103 | 154-180 | 95.3 | | Seal oil | 190-196 | 92 | 127-140 | 94.2 | 0.22 | Whale-oil | 188-193 | 91-92 | 110-136 | 93.5 | 2.04 | Dolphin {Body oil | 197.3 | | 99.5 | 93.07 | 5.6 | oil {Jaw oil | 200 | | 32.8 | 66.28 |65.92 | Porpoise {Body oil | 216-218.8 | 50 | 119.4 | |23.45 | oil {Jaw oil | 253.7 | | 49.6 | 68.41 |65.8 | Neat's-foot oil | 194.3 | 47-48.5 | 69.3-70.4 | | | Cotton-seed | | | | | | stearine. | 194.6-195.1 | 48 | 88.7-92.8 | 96.3 | | Palm oil | 196.3-202 | | 53-57 | 95.6 | 0.5 | Cacao butter | 192.2-193.5 | | 32-41 | 94.59 | 1.6 | Cocoa-nut oil | 250-253 | | 8.5-9.3 | 88.6 | 3.7 | Myrtle wax | 205.7-211.7 | | 2.9 | | | Japan wax | 220-222.4 | | 4.2-8.5 | 90.6 | | Lard | 195.3-196.6 | 27-32 | 57-70 | 96 | | Bone fat | 190.9 | | 46.3-49.6 | | | Tallow | 195-198 | | 36-47 | 95.6 | 0.25 | Butter fat | 221.5-227 | | 26-35 | 87.5 |28.78 | Oleomargarine | 194-203.7 | | 55.3-60 | 95-96 | 2.6 | Sperm oil | 132.5-147 | 47-51 | 84 | | 1.3 | Bottle-nose oil | 126-134 | 41-47 | 77.4-82 | | 1.4 | Carnauba wax | 80-84 | | 13.5 | | | Wool-fat | 98.2-102.4 | | 25-28 | | | Beeswax | 91-96 | | 8.3-11 | | | Spermaceti | 128 | | | | | Chinese wax | 63 | | | | | Tung (Chinese | | | | | | wood oil) | 193 | | 150-165 | | | Soya-bean oil | 190.6-192.9 | 59-61 | 121.3-124 | 95.5 | | ___________________|_____________|___________|____________|_________|______|
*Temperature Correction Table for Hehner's Concentrated Bichromate Solution for Glycerine Analysis
_____________________________________________ | | A | f | Temperature | Corrected Volume | Logarithm | 1 c.c. | _______________|__________________|__________ | | 11deg. C | 0.9980 ccm | 99913 12deg. " | 0.9985 " | 99935 13deg. " | 0.9990 " | 99956 14deg. " | 0.9995 " | 99978 15deg. " | 1.0000 " | 00000 16deg. " | 1.0005 " | 00022 17deg. " | 1.0010 " | 00043 18deg. " | 1.0015 " | 00065 19deg. " | 1.0020 " | 00087 20deg. " | 1.0025 " | 00108 21deg. " | 1.0030 " | 00130 22deg. " | 1.0035 " | 00152 23deg. " | 1.0040 " | 00173 _______________|__________________|__________
*Table of Important Fatty Acids
______________________________________________________________________________ | | | | | | | | Boiling Point | | | | |______________________| |Neutral- | | Mol. | | | Melt- |ization Name | Formula | Wt. | Ordinary | 100 mm | ing |value | | | Pressure | Pressure | Pt. | Mg. KOH ___________|___________________|______|__________|___________|_______|________ | | | | | | Butyric | C_{4}H_{8}O_{2} | 88 | 162.3 | | |637.5 Caproic | C_{6}H_{12}O_{2} | 116 | 199.7 | | |483.6 Caprylic | C_{8}H_{16}O_{2} | 144 | 236-237 | | 16.5 |389.6 Capric | C_{10}H_{20}O_{2} | 172 | 268-270 | 199.5-200 | 31.3 |326.2 Lauric | C_{12}H_{24}O_{2} | 200 | | 225 | 43.6 |280.5 Myristic | C_{14}H_{28}O_{2} | 228 | | 250.5 | 53.8 |246.1 Palmitic | C_{16}H_{32}O_{2} | 256 | | 268.5 | 62 |219.1 Stearic | C_{18}H_{36}O_{2} | 284 | | 291 | 69.2 |197.5 Arachidic | C_{20}H_{40}O_{2} | 302 | | | 75 |185.8 Behenic | C_{22}H_{44}O_{2} | 330 | | | 77-78 |170.0 Cerotic | C_{27}H_{54}O_{2} | 400 | | | 78 |140.25 Melissic | C_{30}H_{60}O_{2} | 442 | | | 90 |126.5 Oleic | C_{18}H_{34}O_{2} | 282 | | 185.5-286 | 14 |198.9 Erucic | C_{22}H_{42}O_{2} | 338 | | | 33-34 |165.9 Linolic | C_{18}H_{32}O_{2} | 280 | | | |200.4 Linolenic | C_{18}H_{30}O_{2} | 278 | | | |201.5 Ricinoleic | C_{18}H_{34}O_{3} | 298 | | | |181.6 ___________|___________________|______|__________|___________|_______|________
*Comparison of Thermometer Scales
n Degree Celsius = 4/5n Degree Reaumur = 32 + 9/5n Degree Fahrenheit
n Degree Reaumur = 5/4n Degree Celsius = 32 + 9/4n Degree Fahrenheit
n Degree Fahrenheit = 5/9 (n - 32) Degree Celsius = 4/9 (n - 32) Deg. R
============================================================================ C. R. F. | C. R. F. | C. R. F. | C. R. F. --------------------|------------------|------------------|----------------- -20 -16 -4 | 20 16 68 | 60 48 140 | 100 80 212 -19 -15.2 -2.2 | 21 16.8 69.8 | 61 48.8 141.8 | 101 80.8 213.8 -18 -14.4 -0.4 | 22 17.6 71.6 | 62 49.6 143.6 | 102 81.6 215.6 -17 -13.6 1.4 | 23 18.4 73.4 | 63 50.4 145.4 | 103 82.4 217.4 -16 -12.8 3.2 | 24 19.2 75.2 | 64 51.2 147.2 | 104 83.2 219.2 | | | -15 -12 5 | 25 20 77 | 65 52 149 | 105 84 221 -14 -11.2 6.8 | 26 20.8 78.8 | 66 52.8 150.8 | 106 84.8 222.8 -13 -10.4 8.6 | 27 21.6 80.6 | 67 53.6 152.6 | 107 85.6 224.6 -12 -9.6 10.4 | 28 22.4 82.4 | 68 54.4 154.4 | 108 86.4 226.4 -11 -8.8 12.2 | 29 23.2 84.2 | 69 55.2 156.2 | 109 87.2 228.2 | | | -10 -8 14 | 30 24 86 | 70 56 158 | 110 88 230 -9 -7.2 15.8 | 31 24.8 87.8 | 71 56.8 159.8 | 111 88.8 231.8 -8 -6.4 17.6 | 32 25.6 89.6 | 72 57.6 161.6 | 112 89.6 233.6 -7 -5.6 19.4 | 33 26.4 91.4 | 73 58.4 163.4 | 113 90.4 235.4 -6 -4.8 21.2 | 34 27.2 93.2 | 74 59.2 165.2 | 114 91.2 237.2 | | | -5 -4 23 | 35 28 95 | 75 60 167 | 115 92 239 -4 -3.2 24.8 | 36 28.8 96.8 | 76 60.8 168.8 | 116 92.8 240.8 -3 -2.4 26.6 | 37 29.6 98.6 | 77 61.6 170.6 | 117 93.6 242.6 -2 -1.6 28.4 | 38 30.4 100.4 | 78 62.4 172.4 | 118 94.4 244.4 -1 -0.8 30.2 | 39 31.2 102.2 | 79 63.2 174.2 | 119 95.2 246.2 | | | 0 0 32 | 40 32 104 | 80 64 176 | 120 96 248 1 0.8 33.8 | 41 32.8 105.8 | 81 64.8 177.8 | 121 96.8 249.8 2 1.6 35.6 | 42 33.6 107.6 | 82 65.6 179.6 | 122 97.6 252.6 3 2.4 37.4 | 43 34.4 109.4 | 83 66.4 181.4 | 123 98.4 253.4 4 3.2 39.2 | 44 35.2 111.2 | 84 67.2 183.2 | 124 99.2 255.2 | | | 5 4 41 | 45 36 113 | 85 68 185 | 125 100 257 6 4.8 42.8 | 46 36.8 114.8 | 86 68.8 186.8 | 126 100.8 258.8 7 5.6 44.6 | 47 37.6 116.6 | 87 69.6 188.6 | 127 101.6 260.6 8 6.4 46.4 | 48 38.4 118.4 | 88 70.4 190.4 | 128 102.4 262.4 9 7.2 48.2 | 49 39.2 120.2 | 89 71.2 192.2 | 129 103.2 264.2 | | | 10 8 50 | 50 40 122 | 90 72 194 | 130 104 266 11 8.8 51.8 | 51 40.8 123.8 | 91 72.8 195.8 | 131 104.8 267.8 12 9.6 53.6 | 52 41.6 125.6 | 92 73.6 197.6 | 132 105.6 269.6 13 10.4 55.4 | 53 42.4 127.4 | 93 74.4 199.4 | 133 106.4 271.4 14 11.2 57.2 | 54 43.2 129.2 | 94 75.2 201.2 | 134 107.2 273.2 | | | 15 12 59 | 55 44 131 | 95 76 203 | 135 108 275 16 12.8 60.8 | 56 44.8 132.8 | 96 76.8 204.8 | 136 108.8 276.8 17 13.6 62.6 | 57 45.6 134.6 | 97 77.6 206.6 | 137 109.6 278.6 18 14.4 64.4 | 58 46.4 136.4 | 98 78.4 208.4 | 138 110.4 280.4 19 15.2 66.2 | 59 47.2 138.2 | 99 79.2 210.2 | 139 111.2 282.2 ============================================================================
*Quantities of Alkali Required for Saponification of Fats of Average Molecular Weight 670
(Cocoanut Oil, Palmkernel Oil)
_________________________________________________ | | | | Liters Alkali | Liters Alkali | | Solution | Solution | Kilos | Sp. Gr. 1.1 | Sp. Gr. 1.2 | ______|_____________________|___________________| | | | | | | NaOH | KOH | NaOH | KOH | ______|__________|__________|_________|_________| | | | | | 1000 | 1875.83 | 1902.99 | 844.67 | 930.35 | 2000 | 3751.66 | 3805.97 | 1689.35 | 1860.70 | 3000 | 5627.50 | 5708.96 | 2534.02 | 2791.04 | 4000 | 7508.33 | 7611.94 | 3378.69 | 3721.39 | 5000 | 9379.16 | 9514.93 | 4223.37 | 4651.74 | 6000 | 11254.99 | 11417.91 | 5068.04 | 5582.09 | 7000 | 13130.82 | 13320.90 | 5912.71 | 6512.44 | 8000 | 15006.66 | 15223.88 | 6757.38 | 7442.78 | 9000 | 16882.49 | 17126.87 | 7602.06 | 8373.13 | 10000 | 18758.32 | 19029.85 | 8446.73 | 9303.48 | ______|__________|__________|_________|_________|
______________________________________________ | | | Liters Alkali | Liters Alkali | Solution | Solution Kilos | Sp. Gr. 1.3 | Sp. Gr. 1.355 ______|___________________|___________________ | | | | | NaOH | KOH | NaOH | KOH ______|_________|_________|_________|_________ | | | | 1000 | 510.27 | 622.71 | 409.61 | 517.97 2000 | 1020.54 | 1245.41 | 819.21 | 1035.95 3000 | 1530.81 | 1868.12 | 1228.82 | 1553.92 4000 | 2041.01 | 2490.83 | 1638.43 | 2071.90 5000 | 2551.35 | 3113.54 | 2048.04 | 2589.87 6000 | 3061.61 | 3736.24 | 2457.65 | 3107.84 7000 | 3571.88 | 4358.95 | 2867.26 | 3625.82 8000 | 4082.15 | 4981.66 | 3276.86 | 4143.79 9000 | 4592.42 | 5604.36 | 3886.47 | 4661.77 10000 | 5102.69 | 6227.02 | 4096.08 | 5179.74 ______|_________|_________|_________|_________
*Quantities of Alkali Required for Saponification of Fats of Average Molecular Weight 860
(Tallow, Cottonseed Oil, Olive Oil, Etc.)
_________________________________________________ | | | | Liters Alkali | Liters Alkali | | Solution | Solution | Kilos | Sp. Gr. 1.1 | Sp. Gr. 1.2 | ______|_____________________|___________________| | | | | | | NaOH | KOH | NaOH | KOH | ______|__________|__________|_________|_________| | | | | | 1000 | 1461.40 | 1482.56 | 658.05 | 724.81 | 2000 | 2922.81 | 2965.12 | 1316.12 | 1449.61 | 3000 | 4384.21 | 4447.67 | 1974.18 | 2174.42 | 4000 | 5845.62 | 5930.23 | 2632.24 | 2899.22 | 5000 | 7307.02 | 7412.79 | 3290.80 | 3624.03 | 6000 | 8768.42 | 8895.85 | 3948.35 | 4348.84 | 7000 | 10229.83 | 10377.91 | 4606.41 | 5073.64 | 8000 | 11691.23 | 11860.45 | 5264.47 | 5798.45 | 9000 | 13152.64 | 13343.02 | 5922.53 | 6523.25 | 10000 | 14614.04 | 14825.58 | 6580.59 | 7248.06 | ______|__________|__________|_________|_________| ______________________________________________ | | | Liters Alkali | Liters Alkali | Solution | Solution Kilos | Sp. Gr. 1.3 | Sp. Gr. 1.355 ______|___________________|___________________ | | | | | NaOH | KOH | NaOH | KOH ______|_________|_________|_________|_________ | | | | 1000 | 397.54 | 485.13 | 319.11 | 403.54 2000 | 795.07 | 970.27 | 638.23 | 807.08 3000 | 1192.61 | 1455.40 | 957.34 | 1210.61 4000 | 1590.14 | 1940.53 | 1276.45 | 1614.15 5000 | 1987.68 | 2425.67 | 1595.57 | 2017.69 6000 | 2385.21 | 2910.80 | 1914.68 | 2421.23 7000 | 2782.75 | 3395.93 | 2233.79 | 2824.77 8000 | 3180.28 | 3881.06 | 2552.90 | 3228.30 9000 | 3577.82 | 4366.20 | 2872.02 | 3631.84 10000 | 3975.35 | 4851.33 | 3191.13 | 4035.38 ______|_________|_________|_________|_________
DENSITY AND STRENGTH OF SULPHURIC ACID (SIDERSKY).
Column Headings: A: Degrees Twaddell B: Sp. Gr. at 15deg. C. C: % of pure acid (H_{2}SO_{4}). D: Equivalent (in cc.) of a kilo of pure acid. E: Equivalent (in cc.) of a liter of pure acid.
=========================================
[A] [B] [C] [D] [E] _________________________________________
1 1.007 1.9 52.620 96.930 3 1.014 2.8 35.710 66.450 4 1.022 3.8 25.650 47.230 6 1.029 4.8 20.410 37.582 8 1.037 5.8 16.670 30.690 9 1.045 6.8 14.085 25.938 10 1.052 7.8 12.198 22.460 12 1.062 8.8 10.755 19.803 13 1.067 9.8 9.524 17.540 15 1.075 10.9 8.547 15.740 17 1.083 11.9 7.752 14.278 18 1.091 13.0 7.042 12.969 20 1.100 14.1 6.452 11.882 22 1.108 15.2 5.953 10.962 23 1.116 16.2 5.526 10.177 25 1.125 17.3 5.405 9.954 27 1.134 18.5 4.76 8.770 29 1.142 19.6 4.465 8.223 30 1.152 20.8 4.184 7.723 32 1.162 22.2 3.876 7.138 34 1.171 23.3 3.663 6.745 36 1.180 24.5 3.541 6.521 38 1.190 25.8 3.258 5.999 40 1.200 27.1 3.077 5.666 42 1.210 28.4 2.907 5.353 44 1.220 29.6 2.770 5.102 46 1.231 31.0 2.618 4.865 48 1.241 32.2 2.500 4.604 50 1.252 33.4 2.392 4.406 53 1.263 34.7 2.283 4.205 55 1.274 36.0 2.179 4.012 57 1.285 37.4 2.079 3.829 60 1.297 38.8 1.988 3.661 62 1.308 40.2 1.905 3.508 64 1.320 41.6 1.821 3.354 66 1.332 43.0 1.745 3.214 69 1.345 44.4 1.665 3.085 71 1.357 45.5 1.621 2.985 74 1.370 46.9 1.558 2.869 77 1.383 48.3 1.497 2.757 80 1.397 49.8 1.436 2.646 82 1.410 51.2 1.386 2.551 85 1.424 52.6 1.335 2.459 88 1.438 54.0 1.287 2.370 91 1.453 55.4 1.237 2.270 94 1.468 56.9 1.195 2.200 97 1.483 58.3 1.156 2.130 100 1.498 59.6 1.116 2.050 103 1.514 61.0 1.080 1.980 106 1.530 62.5 1.045 1.930 108 1.540 64.0 1.010 1.860 113 1.563 65.5 0.975 1.800 116 1.580 67.0 0.950 1.740 120 1.597 68.6 0.917 1.690 123 1.615 70.0 0.888 1.630 127 1.634 71.6 0.855 1.570 130 1.652 73.2 0.845 1.520 134 1.671 74.7 0.800 1.470 138 1.691 76.4 0.774 1.430 142 1.711 78.1 0.749 1.390 146 1.732 79.9 0.722 1.320 151 1.753 81.7 0.705 1.280 155 1.774 84.1 0.672 1.235 160 1.798 86.5 0.639 1.190 164 1.819 89.7 0.609 1.120 168 1.842 100.0 0.544 1.000
*Densities of Potassium Carbonate Solutions at 15 C (Gerlach)
======================= | | | Per cent | Sp. Gr. | of pure | | K_{2}CO_{3} | ________|_____________| | | 1.00914 | 1 | 1.01829 | 2 | 1.02743 | 3 | 1.03658 | 4 | 1.04572 | 5 | 1.05513 | 6 | 1.06454 | 7 | 1.07396 | 8 | 1.08337 | 9 | 1.09278 | 10 | 1.10258 | 11 | 1.11238 | 12 | 1.12219 | 13 | 1.13199 | 14 | 1.14179 | 15 | 1.15200 | 16 | 1.16222 | 17 | 1.17243 | 18 | 1.18265 | 19 | 1.19286 | 20 | 1.20344 | 21 | 1.21402 | 22 | 1.22459 | 23 | 1.23517 | 24 | 1.24575 | 25 | 1.25681 | 26 | 1.26787 | 27 | 1.27893 | 28 | 1.28999 | 29 | 1.30105 | 30 | 1.31261 | 31 | 1.32417 | 32 | 1.33573 | 33 | 1.34729 | 34 | 1.35885 | 35 | 1.37082 | 36 | 1.38279 | 37 | 1.39476 | 38 | 1.40673 | 39 | 1.41870 | 40 | 1.43104 | 41 | 1.44338 | 42 | 1.45573 | 43 | 1.46807 | 44 | 1.48041 | 45 | 1.49314 | 46 | 1.50588 | 47 | 1.51861 | 48 | 1.53135 | 49 | 1.54408 | 50 | 1.55728 | 51 | 1.57048 | 52 | 1.57079 | 53.024 | ________|_____________|
*Constants of Certain Fatty Acids and Triglycerides
========================================================= | | | | | | Per cent Yield Triglycerides | Mol. Wt. | Mol. Wt. |__________________ of | of Fatty | of Tri- | | | of Fatty | glycerides | Fatty | Glycerine | | | Acid | ______________|__________|____________|_______|___________ | | | | Stearic Acid | 284 | 890 | 95.73 | 10.34 Oleic Acid | 282 | 884 | 95.70 | 10.41 Margaric Acid | 270 | 848 | 95.52 | 10.85 Palmitic Acid | 256 | 806 | 95.28 | 11.42 Myristic Acid | 228 | 722 | 94.47 | 12.74 Lauric Acid | 200 | 638 | 94.04 | 14.42 Capric Acid | 172 | 594 | 93.14 | 15.48 Caproic Acid | 116 | 386 | 90.16 | 23.83 Butyric Acid | 88 | 302 | 87.41 | 30.46 ______________|__________|____________|_______|___________
PERCENTAGES OF SOLID CAUSTIC SODA AND CAUSTIC POTASH IN CAUSTIC LYES ACCORDING TO BAUME SCALE.
Degrees % % Baume. NaOH KOH
1 0.61 0.90 2 0.93 1.70 3 2.00 2.60 4 2.71 3.50 5 3.35 4.50 6 4.00 5.60 7 4.556 6.286 8 5.29 7.40 9 5.87 8.20 10 6.55 9.20 11 7.31 10.10 12 8.00 10.90 13 8.68 12.00 14 9.42 12.90 15 10.06 13.80 16 10.97 14.80 17 11.84 15.70 18 12.64 16.50 19 13.55 17.60 20 14.37 18.60 21 15.13 19.50 22 15.91 20.50 23 16.77 21.40 24 17.67 22.50 25 18.58 23.30 26 19.58 24.20 27 20.59 25.10 28 21.42 26.10 29 22.64 27.00 30 23.67 28.00 31 24.81 28.90 32 25.80 29.80 33 26.83 30.70 34 27.80 31.80 35 28.83 32.70 36 29.93 33.70 37 31.22 34.90 38 32.47 35.90 39 33.69 36.90 40 34.96 37.80 41 36.25 38.90 42 37.53 39.90 43 38.80 40.90 44 39.99 42.10 45 41.41 43.40 46 42.83 44.60 47 44.38 45.80 48 46.15 47.10 49 47.58 48.25 50 49.02 49.40
GLYCERINE CONTENT OF MORE COMMON OILS AND FATS USED IN SOAP MAKING.
Kind. Theoretical Average Free % Pure Yield Yield of Pure Fatty Acid in Glycerine Soap Lye Glycerine of Commercial in Commercial 80% Crude Neutral Oil Oil. Oil. Glycerine. or Fat.
Beef Tallow 10.7 5 10.2 12.75 Bone Grease 10.5 20-50 5.2- 8.4 6.5-10.5 Castor Oil 9.8 0.5-10 8.8- 9.8 11.0-12.45 Cocoanut Oil 13.9 3-5 13.2-13.5 16.5-16.9 Cocoanut Oil Off 15-40 8.3-11.8 10.37-14.75 Corn Oil 10.4 1-10 9.3-10.3 11.62-12.9 Cottonseed Oil 10.6 Trace 10.6 13.25 Hog Grease 10.6 0.5-1 10.5-10.6 13.12-13.25 Horse Grease 10.6 1-3 10.5-10.6 13.12-13.25 Olive Oil 10.3 2-25 7.7-10.2 9.62-12.75 Olive Foots 30-60 4-7 5-8.75 Palm Oil 11.0 10-50 5.5-10 6.87-12.5 Palmkernel Oil 13.3 4-8 12.2-12.8 15.25-16 Peanut Oil 10.4 5-20 8.3-9.9 10.37-12.37 Soya Bean Oil 10.4 2 10.2 12.75 Train Oil 10.0 2-20 8-9.8 10.0-12.25 Vegetable Tallow 10.9 1-3 10.5-10.8 13.12-13.5
*Table of Specific Gravities of Pure Commercial Glycerine with Corresponding Percentage of Water. Temperature 15 C.
------------------+------------------ Sp. Gr. % Water | Sp. Gr. % Water 1.262 0 | 1.160 38 1.261 1 | 1.157 39 1.258 2 | 1.155 40 1.255 3 | 1.152 41 1.2515 4 | 1.149 42 1.250 5 | 1.1464 43 1.2467 6 | 1.1437 44 1.2450 7 | 1.141 45 1.243 8 | 1.1377 46 1.241 9 | 1.1353 47 1.237 10 | 1.1326 48 1.235 11 | 1.1304 49 1.2324 12 | 1.127 50 1.229 13 | 1.125 51 1.2265 14 | 1.1224 52 1.2245 15 | 1.1204 53 1.2225 16 | 1.117 54 1.2185 17 | 1.114 55 1.2174 18 | 1.112 56 1.2142 19 | 1.109 57 1.211 20 | 1.106 58 1.207 21 | 1.103 59 1.203 22 | 1.1006 60 1.2004 23 | 1.088 65 1.198 24 | 1.075 70 1.195 25 | 1.0623 75 1.1923 26 | 1.049 80 1.189 27 | 1.0365 85 1.188 28 | 1.0243 90 1.1846 29 | 1.0218 91 1.182 30 | 1.0192 92 1.179 31 | 1.0168 93 1.176 32 | 1.0147 94 1.1734 33 | 1.0125 95 1.171 34 | 1.01 96 1.168 35 | 1.0074 97 1.165 36 | 1.0053 98 1.163 37 | 1.0026 99 ------------------+------------------
Table of Percentage, Specific Gravity and Beaume Degree of Pure Glycerine Solutions
=========+===========+===========++=========+===========+=========== Per cent |Sp. Gr. |Degree ||Per cent |Sp. Gr. |Degree Water |Champion |Beaume ||Water |Champion |Beaume |and Pellet |(Berthelot)|| |and Pellet |(Berthelot) =========+===========+===========++=========+===========+=========== 0 | 1.2640 | 31.2 || 11.0 | 1.2350 | 28.6 0.5 | 1.2625 | 31.0 || 11.5 | 1.2335 | 28.4 1.0 | 1.2612 | 30.9 || 12.0 | 1.2322 | 28.3 1.5 | 1.2600 | 30.8 || 12.5 | 1.2307 | 28.2 2.0 | 1.2585 | 30.7 || 13.0 | 1.2295 | 28.0 2.5 | 1.2575 | 30.6 || 13.5 | 1.2280 | 27.8 3.0 | 1.2560 | 30.4 || 14.0 | 1.2270 | 27.7 3.5 | 1.2545 | 30.3 || 14.5 | 1.2255 | 27.6 4.0 | 1.2532 | 30.2 || 15.0 | 1.2242 | 27.4 4.5 | 1.2520 | 30.1 || 15.5 | 1.2230 | 27.3 5.0 | 1.2505 | 30.0 || 16.0 | 1.2217 | 27.2 5.5 | 1.2490 | 29.9 || 16.5 | 1.2202 | 27.0 6.0 | 1.2480 | 29.8 || 17.0 | 1.2190 | 26.9 6.5 | 1.2465 | 29.7 || 17.5 | 1.2177 | 26.8 7.0 | 1.2455 | 29.6 || 18.0 | 1.2165 | 26.7 7.5 | 1.2440 | 29.5 || 18.5 | 1.2150 | 26.5 8.0 | 1.2427 | 29.3 || 19.0 | 1.2137 | 26.4 8.5 | 1.2412 | 29.2 || 19.5 | 1.2125 | 26.3 9.0 | 1.2400 | 29.0 || 20.0 | 1.2112 | 26.2 9.5 | 1.2390 | 28.9 || 20.5 | 1.2100 | 26.0 10.0 | 1.2375 | 28.8 || 21.0 | 1.2085 | 25.0 10.5 | 1.2362 | 28.7 || | | =========+===========+===========++=========+===========+===========
*Table of Specific Gravities of Pure Glycerine Solutions with Corresponding Beaume Degree and Percent Water
--------+--------+-------+---------+--------+-------- Per cent| Sp. Gr.| Degree| Percent | Sp. Gr.| Degree Water | | Beaume| Water | | Beaume --------+--------+-------+---------+--------+-------- | | | | | 0.0 | 1.2640 | 31.2 | 1.0 | 1.2612 | 30.9 0.5 | 1.2625 | 31.0 | 1.5 | 1.2600 | 30.8 2.0 | 1.2585 | 30.7 | 12.0 | 1.2322 | 28.3 2.5 | 1.2575 | 30.6 | 12.5 | 1.2307 | 28.2 3.0 | 1.2560 | 30.4 | 13.0 | 1.2295 | 28.0 3.5 | 1.2545 | 30.3 | 13.5 | 1.2280 | 27.8 4.0 | 1.2532 | 30.2 | 14.0 | 1.2270 | 27.7 4.5 | 1.2520 | 30.1 | 14.5 | 1.2255 | 27.6 5.0 | 1.2505 | 30.0 | 15.0 | 1.2242 | 27.4 5.5 | 1.2490 | 29.9 | 15.5 | 1.2230 | 27.3 6.0 | 1.2480 | 29.8 | 16.0 | 1.2217 | 27.2 6.5 | 1.2465 | 29.7 | 16.5 | 1.2202 | 27.0 7.0 | 1.2455 | 29.6 | 17.0 | 1.2190 | 26.9 7.5 | 1.2440 | 29.5 | 17.5 | 1.2177 | 26.8 8.0 | 1.2427 | 29.3 | 18.0 | 1.2165 | 26.7 8.5 | 1.2412 | 29.2 | 18.5 | 1.2150 | 26.5 9.0 | 1.2400 | 29.0 | 19.0 | 1.2137 | 26.4 9.5 | 1.2390 | 28.9 | 19.5 | 1.2125 | 26.3 10.0 | 1.2375 | 28.8 | 20.0 | 1.2112 | 26.2 10.5 | 1.2362 | 28.7 | 20.5 | 1.2100 | 26.0 11.0 | 1.2350 | 28.6 | 21.0 | 1.2085 | 25.9 11.5 | 1.2335 | 28.4 | | | --------+--------+-------+---------+--------+--------
INDEX
A
Acetin process for the determination of glycerol, 155.
Acid, Clupanodonic, 20.
Acid, Hydrochloric, 111.
Acid, Lauric, 2.
Acid, Myristic, 2.
Acid, Napthenic, 24.
Acid, Oleic, 15, 19.
Acid, Palmitic, 2.
Acid, Pinic, 22.
Acid, Resin, 144.
Acid, Stearic, 15, 19.
Acid, Sulfuric, 112.
Acid, Sylvic, 22.
Acid saponification, 120.
Air bleaching of palm oil, 12.
Albuminous matter, Removal from tallow, 6.
Alcohol, Denatured, 82.
Alcoholic method for free alkali in soap, 139.
Alkali Blue 6 B, indicator, 129.
Alkali, Total, determination of in soap, 147.
Alkalis, 25.
Alkalis used in soap making, Testing of, 134.
Amalgamator, 33.
Analysis, Glycerine, International, 150.
Analysis, Soap, 137.
Analysis, Standard methods for fats and oils, 165-196.
Aqueous saponification, 121.
Arachis oil, 79.
Autoclave saponification, 118.
Automobile soaps, 41.
B
Barrels, sampling, 168.
Baume scale, 25.
Bayberry wax, Use in shaving soap, 89.
Bichromate Process for glycerol determination, 160.
Bleaching, Fullers' earth process for tallow, 4.
Bleaching palm oil by bichromate method, 9.
Bleaching palm oil by air, 12.
Bosshard & Huggenberg method for determination of free alkali, 140.
Bunching of soap, 52.
C
Candelite, 96.
Candle tar, 125.
Carbolic soap, 77.
Carbon Dioxide, Formation of in carbonate saponification, 45.
Carbonate, potassium, 29.
Carbonate, saponification, 35, 45.
Carbonate, sodium, 28.
Castile soap, 79.
Castor oil ferment, 121.
Castor oil, Use of in transparent soaps, 83.
Caustic potash, 26.
Caustic potash, Electrolytic, 27.
Caustic soda, 26.
Changes in soap-making, 36.
Chemist, Importance of, 127.
Chipper, Soap, 32.
Chip soap, 54.
Chip soap, Cold made, 55.
Chip soap, Unfilled, 56.
Chrome bleaching of palm oil, 9.
Cloud test for oil, Standard method, 182-183.
Clupanodonic acid, 20.
Cocoanut oil, 6.
Cold cream soap, 78.
Cold made chip soaps, 55.
Cold made toilet soaps, 72.
Cold made transparent soaps, 84.
Cold process, 35, 43.
Colophony, 22.
Coloring soap, 75.
Copra, 7.
Corn oil, 14.
Corrosive sublimate, 78.
Cotton goods. Soaps used for, 103.
Cottonseed oil, 14.
Cream, Shaving, 90.
Crude glycerine, 113.
Crutcher, 32.
Curd soap, 71.
Cutting table, 32.
D
Determination of free fatty acid, 128.
Determination of unsaponifiable matter, 132.
Distillation of fatty acids, 125.
Drying machine, 32.
E
Enzymes, 17.
Eschweger soap, 81.
Examination of fats and oils, 128.
F
Fahrion's method for moisture, 138.
Fats and oils, Examination of, 128.
Fats and oils used in soap manufacture, 3.
Fatty acids, 14.
Fatty acids, Distillation of, 125.
Ferments, Splitting fats with, 121.
Fillers for laundry soaps, 53.
Fillers for soap powders, 58.
Finishing change, 36.
Fish oils, 20.
Floating soap, 62.
Formaldehyde soap, 78.
Frames, 31.
Free alkali in soap, Determination of, 139.
Free fatty acid, Determination of, 128.
Free fatty acids, Extraction from tallow, 6.
Free fatty acid, Standard method of dilu., 174. Note on method, 188-189.
Full boiled soaps, 35.
Fullers' earth bleaching of tallow, 4.
G
Glycerides, 2.
Glycerine, 2.
Glycerine analysis, 150.
Glycerine change, 36.
Glycerine, Crude, 113.
Glycerine in spent lyes, Recovery of, 106.
Glycerine in soap, Determination of, 149.
Glycerine, Sampling crude, 162.
Glycerine soaps, 83.
Glycerol content, Ways of calculating actual, 159.
Glycerol determination, Acetin process, 155.
Glycerol determination, Bichromate process for, 160.
Graining soap, 30.
Grease, 21.
Grease, Bleaching, 21.
Grinding soap, 34.
H
Hand Paste, 93.
Hard water, 29.
Hardened oils in toilet soap, Use of, 96.
Hydrocarbon oils, 2.
Hydrogenating oils, 19.
Hydrolysis of fats and oils, 17.
Hydrolytic dissociation of soap, 1.
Hydrometers, 25.
I
Indicators, Action, 135-6.
Insoluble impurities in fatty oils, Determination of (standard method), 172. Note on method, 187.
Insoluble matter in soap, determination of, 143.
International committee on glycerine analysis, 150.
Iodine manufacturing oil, 191.
Iodine member Wijs method, Standard, 177-181. Note on method, 191.
Iodine soap, 78.
J
Joslin, ref., 113.
K
"Killing" change, 36.
Koettstorfer number (Standard method), 181-182.
Kontakt reagent, 117.
Krebitz Process, 123.
Krutolin, 96.
L
Leiste & Stiepel method for rosin in soap, 146.
Liebermann, Storch reaction, 144.
Light powders, 60.
Laundry soap, 48.
LeBlanc Process, 28.
Lewkowitsch, ref., 17, 146.
Lime saponification, 118.
Lime, Use in Krebitz Process, 123.
Lime, Use in treatment of glycerine water, 116.
Liquid medicinal soaps, 79.
Liquid soaps, 94.
Lyes, Spent, 37.
M
Magnesia, Use in autoclave saponification, 120.
Manganese sulfate, Use of as catalyzer in fermentative cleavage of fats, 122.
Marine soaps, 39.
Medicinal soaps, 76.
Medicinal soaps, Less important, 78.
Medicinal soaps, Therapeutic value of, 76.
Melting point of fat or oil, Standard method, 193.
Mercury soaps, 78.
Metallic soaps, 1.
Methyl orange, indicator, 136.
Meyerheim, ref., 21.
Mill soap, 32.
Moisture in soap, Determination of, 138, 130.
Moisture and volatile matter in fats and oils, Standard method for detm. of, 170. Note on method, 184-185.
Mottle in soap, 81.
Mug shaving soap, 90.
N
Naphtha, Incorporation in soap, 49.
Naphthenic acids, 24.
Nigre, 36.
Normal acids, Equivalent in alkalis, 136.
O
Oils and fats, 1.
Oils and fats, Chemical constants, 18.
Oils and fats, Distinction, 1.
Oils and fats, Preserving, 18.
Oils and fat, Nature of used in soap manufacture, 2.
Oils and fats, Rancidity of, 16.
Oil hardening, 19.
Oleic acid, 15, 19.
Olein, 2, 19.
Olive oil, 14.
Olive oil foots, 14.
Organoleptic methods, 127.
P
Palmatin, 2.
Palm kernel oil, 8.
Palmitic acid, 2.
Palm oil, 8.
Palm oil, air bleaching, 12.
Palm oil, Chrome bleaching of, 9.
Palm oil soap, 66.
Pearl ash, 29.
Perfuming and coloring toilet soaps, 73.
Peroxide soap, 78.
Petroff reagent, 117.
Pfeilring reagent, 117.
Phenol, 77.
Phenolphthalein, indicator, 38.
Phenolphthalein, Using as indicator, 51.
Phenols, Soaps containing, 77.
Pinic acid, 22.
Plodder, 33.
Potash from wood ash, 27.
Potassium carbonate, 29.
Powders, Light, 60.
Powders, Scouring, 61.
Powders, Shaving, 90.
Powders, Soap, 56.
Precipitation test for treated spent lyes, 110.
Prevention of rancidity, 18.
Pumice or sand soaps, 93.
Purple shade in soap, 75.
R
Rancidity of oils and fats, 16.
Rancidity, Prevention, 18.
Recovery of glycerine from spent lye, 106.
Red oil, 15.
Red oil, Saponified, 15.
Resin acids, Total fatty and, Determination of in soap, 144.
Ribot, ref., 20.
Rosin, 22.
Rosin, Determination of in soap, 144.
Rosin saponification, 23.
Run and glued up soaps, 69.
Run soaps, 39.
S
Sal soda, 29.
Salt, 30.
Salting out, 30.
Salt "pickle," 37.
Sampling crude glycerine, 162.
Sampling for standard method, 166. Note on, 184.
Sampling oils and fats, 128.
Sampling soap, 137.
Saponification by ferments, 121.
Saponification, Acid, 120.
Saponification, Aqueous, 121.
Saponification, Autoclave, 118.
Saponification, Carbonate, 45.
Saponification defined, 2, 105.
Saponification, Lime, 118.
Saponification number, 181-182.
Saponification, Rosin, 23.
Saponification, Various methods, 105.
Scouring and fulling soaps for wool, 98.
Scouring powders, 61.
Scouring soap, 61.
Semi-boiled laundry soaps, 49.
Semi-boiled process, 44.
Shaving cream, 90.
Shaving powder, 90.
Shaving soaps, 87.
Silica and silicates, Determination of in soap, 148.
Silk dyeing, 102.
Silk industry, Soaps used in, 101.
Slabber, 32.
Smith method for moisture in soap, 138.
Soap analysis, 137.
Soap, Automobile, 41.
Soap, Carbolic, 71.
Soap, Castile, 79.
Soap, Chip, 54.
Soap Chip, cold made, 55.
Soap, Chip, unfilled, 56.
Soap, Cold cream, 78.
Soap, Coloring, 75.
Soap containing phenols, 77.
Soap, Curd, 71.
Soap, Defined, 1.
Soap, Determination insoluble matter, 143.
Soap, Determining glycerine in, 149.
Soap, Eschweger, 81.
Soap, Floating, 62.
Soap, Formaldehyde, 78.
Soap for wool, Scouring and fulling, 98.
Soap, Full boiled, 35.
Soap, Iodine, 78.
Soap kettle, 31.
Soap, Laundry, 48.
Soap, Liquid, 94.
Soap lye crude glycerine, 113.
Soap, Marine, 39.
Soap, Medicinal, 76.
Soap, Medicinal, less important, 78.
Soap, Mercury, 78.
Soap, Metallic, 1.
Soap, Peroxide, 78.
Soap powders, 56.
Soap, Pumice or sand, 93.
Soap, Rosin settled, 50.
Soap, Run and glued up, 69.
Soap, Scouring, 61.
Soap, Semi-boiled laundry, 49.
Soap, Shaving, 87.
Soap, Sulphur, 77.
Soap, Tannin, 78.
Soap, Tar, 77.
Soap, Test for color of, 133.
Soap, Textile, 98.
Soap, Toilet, 65.
Soap, Toilet cheaper, 68.
Soap, Toilet, cold made, 72.
Soap, Toilet perfuming and coloring, 73.
Soap, Transparent, 82.
Soap, Transparent, cold made, 84.
Soap used for cotton goods, 103.
Soap used in the silk industry, 101.
Soap, Witch hazel, 78.
Soap, Wool thrower's, 100.
Soap, Worsted finishing, 101.
Soda ash, 28.
Sodium carbonate, 28.
Sodium perborate, Use of in soap powders, 57.
Soft soaps, 40.
Soluble mineral matter detm. of in fats and oils, 173. Note on method, 187-188.
Solvay process, 28.
Soya bean oil, 14.
Spent lye, Recovery of glycerine from, 106.
Spent lyes, 37.
Spent lyes, Treatment of for glycerine recovery, 107.
Splitting fats with ferments, 121.
Standard methods of analysis for fats and oils, 165-196.
Starch and gelatine, Determination in soap, 143.
Stearic acid, 15, 19.
Stearin, 2, 19.
Strengthening change, 36.
Strengthening lyes, 38.
Strunz crutcher, 63.
Sugar in soap, Determination of, 150.
Sugar, Use in transparent soap, 83.
Sulfate of alumina, Use of in spent lyes, 108.
Sulphonated oils, 104.
Sulphur soaps, 77.
Sweating of soap, 62.
Sweet water, 119.
Sylvic acid, 22.
T
Talgol, 96.
Tallow, 4.
Tallow, Fullers' earth bleaching of, 4.
Tallow, Improving color by extraction of free fatty acid, 6.
Tannin soap, 78.
Tar soap, 77.
Test for color of soap, 133.
Testing of alkalis used in soap making, 134.
Textile soaps, 98.
Titer, 130.
Tank cars, Sampling, 166.
Tierces, Sampling, 168.
Titer, Standard method, 175.
Titer, Note on, 189.
Tung oil, Note one iodine, number of, 180.
Toilet soap, 65.
Toilet soaps, Cheaper, 68.
Toilet soap, Use of hardened oils in, 96.
Total alkali, Determination of in soap, 147.
Total fatty and resin acids, Determination of in soap, 144.
Train oils, 20.
Transparent soap, 82.
Transparent soap, Cold made, 84.
Troweling soap, 52.
Tsujimoto, ref., 20.
Tubes for transparent soap, 85.
Turkey red oil, 104.
Twaddle scale, 25.
Twitchell method for rosin, 145.
Twitchell process, 113.
Twitchell process, Advantages, 113.
U
Unsaponifiable matter, Determination of in oils and fats, 132.
Unsaponifiable matter, Determination of in soap, 148.
Unsaponifiable matter, determination of by standard method, 176.
V
Vacuum Oven, Standard, 176.
Vegetable oils, 6.
W
Water, 29.
Water, Hard, 29.
Witch hazel soap, 78.
Wool thrower's soap, 100.
Worsted finishing soaps, 101.
Z
Zinc oxide, Use of in autoclave saponification, 120.
Zinc oxide, Use of in soap, 33.
LITERATURE OF THE CHEMICAL INDUSTRIES
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A list of standard books relating to soapmaking and allied industries.
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~Askinson, George W.~ Perfumes and Cosmetics. Their preparation and manufacture. Fourth Edition, translated from the German, and revised with additions by W. L. Dudley. 32 illustrations. 6-1/4 x 9-1/2. Cloth. 354 pp. New York, 1915. ~$5.00~
~Chalmers, T. W.~ The Production and Treatment of Vegetable Oils. Including chapters on the refining of oils, the hydrogenation of oils, the generation of hydrogen, soap making, the recovery and refining of glycerine, and the splitting of oils. 95 illustrations, 9 folding plates. 8 x 11-1/2. Cloth. 163 pp. London, 1919. ~$7.50~
~Deite, C.~ Manual of Toilet Soap-Making. Comprising toilet soaps, medicated soaps, and other specialties. Second Revised Edition. 85 illustrations. 6-1/2 x 10. Cloth. 356 pp. London, 1920. ~$7.50~
~Ellis, Carleton G.~ The Hydrogenation of Oils, Catalyzers and Catalysis and the Generation of Hydrogen and Oxygen. Second Edition, thoroughly revised and enlarged. 240 illustrations. 6-1/4 x 9-1/2. Cloth. 767 pp. N. Y., 1919. ~$7.50~
~Fischer, M. H.~ Soaps and Proteins, Their Colloid Chemistry in Theory and Practice. With the collaboration of G. D. McLaughlin and M. O. Hooker. 114 illustrations. 6 x 9-1/4. Cloth. 281 pp. New York, 1921. ~$4.00~
~Holde, D.~ The Examination of Hydrocarbon Oils, and of the Saponifiable Fats and Waxes. Translated from the Fourth German Edition by Edward Mueller. 115 illustrations. 6-1/4 x 9-1/4. Cloth. 499 pp. N. Y., 1915. ~Net, $5.00~
~Hurst, G. H~. Soaps. A practical manual of the manufacture of domestic, toilet and other soaps. Second Edition. 66 illustrations. 6 x 8-3/4. Cloth. 385 pp. London, 1907. ~$6.00~
~Hurst, George H., and Simmons, W. H.~ Textile Soaps and Oils. A handbook on the preparation, properties, and analysis of the soaps and oils and in textile manufacturing, dyeing and printing. Third Edition, revised. 12 illustrations. 5-1/2 x 8-3/4. Cloth. 212 pp. London, 1921. ~$4.00~
~Koller, T. Cosmetics.~ A handbook of the manufacture, employment, and testing of all cosmetic materials and cosmetic specialties, with numerous recipes. Translated from the German. Third Edition. 5 x 7-1/2. Cloth. 264 pp. London, 1920. ~$3.50~
~Koppe, S. W. Glycerine.~ Its introduction, Uses and Examination. For chemists, perfumers, soapmakers, pharmacists, and explosives technologists. 7 illustrations. 5-1/4 x 7-1/2. Cloth. 260 pp. New York, 1915. ~$3.50~
~Lamborn, L. L.~ Modern Soaps, Candles, and Glycerin. A practical manual of modern methods of utilization of fats and oils in the manufacture of soaps and candles, and the recovery of glycerin. 228 illustrations. 6-1/2 x 9-1/4. Cloth. 708 pp. N. Y., 1906. ~$10.00~
~Murray, B. L.~ Standards and Tests for Reagent Chemicals. 6 x 9. Cloth. 400 pp. New York, 1920. ~$3.00~
~Parry, Ernest J.~ The Chemistry of Essential Oils and Artificial Perfumes. Vol. I, Monographs on Essential Oils. Fourth Edition, revised and enlarged. 51 illustrations. 6-1/4 x 10. Cloth. 557 pp. London, 1921. ~$9.00~
Vol. II. Constituents of Essential Oils, Synthetic Perfumes and Isolated Aromatics, and the Analysis of Essential Oils. Third Edition, revised and enlarged. Illustrated. 351 pp. London, 1919. ~$7.00~
~Partington, J. R.~ The Alkali Industry. 63 illustrations. 5-1/2 x 8-1/2. Cloth. 318 pp. London, 1918. ~$3.00~
~Rogers, Allen.~ Industrial Chemistry. A manual for the student and manufacturer. Third Edition, thoroughly revised and enlarged. 377 illustrations. 6-1/2 x 9-3/4. Flexible fabrikoid. 1255 pp. New York, 1920. ~$7.50~
~Scott, Wilfred W.~ (Editor). Standard Methods of Chemical Analysis. A manual of analytical methods and general reference for the analytical chemist and for the advanced student. Second Edition, revised, with additional tables. 142 illustrations, 3 color plates. 7 x 9-1/4. Cloth. 900 pp. N. Y., 1917. ~$7.50~
~Simmons, W. H.~ Fats, Waxes and Essential Oils. ~In Press.~
~Simmons, William H.~ Soap. Its composition, manufacture and properties. 11 illustrations. 4-3/4 x 7-1/4. Cloth. 133 pp. London, 1916. ~$1.00~
~Simmons, W. H., and Appleton, H. A.~ The Handbook of Soap Manufacture. 27 illustrations. 6 x 9. Cloth. 166 pp. London, 1908. ~$4.00~
~Van Nostrand's Chemical Annual.~ Edited by John C. Olsen. A handbook of useful data for analytical manufacturing and investigating chemists and chemical students. Fourth Issue, enlarged. 5 x 7-1/2. Flexible fabrikoid. 785 pp. New York, 1918. ~$3.00~
~Watt, A.~ Art of Soapmaking. A practical handbook of the manufacture of hard and soft soaps, toilet soaps, etc. Seventh Edition, revised and enlarged. 43 illustrations. 5-1/4 x 7-1/2. Cloth. 323 pp. London, 1918. ~$4.00~
~Wright, C. R. A.~ Animal and Vegetable Fixed Oils, Fats, Butters, and Waxes: Their Preparation and Properties, and the Manufacture Therefrom of Candles, Soaps, and Other Products. Third Edition, revised and greatly enlarged by C. Ainsworth Mitchell. 185 illustrations, 3 plates. 6 x 9. Cloth. 953 pp. London, 1921. ~$16.50~