Part II

. Sect. X. we have already given a history of the discovery of that singular substance, with some observations upon the mode of its existence in vegetable and animal bodies. The best method of obtaining this acid in a state of purity is by burning well purified phosphorus under bell-glasses, moistened on the inside with distilled water; during combustion it absorbs twice and a half its weight of oxygen; so that 100 parts of phosphoric acid is composed of 28-1/2 parts of phosphorus united to 71-1/2 parts of oxygen. This acid may be obtained concrete, in form of white flakes, which greedily attract the moisture of the air, by burning phosphorus in a dry glass over mercury.

To obtain phosphorous acid, which is phosphorus less oxygenated than in the state of phosphoric acid, the phosphorus must be burnt by a very slow spontaneous combustion over a glass-funnel leading into a crystal phial; after a few days, the phosphorus is found oxygenated, and the phosphorous acid, in proportion as it forms, has attracted moisture from the air, and dropped into the phial. The phosphorous acid is readily changed into phosphoric acid by exposure for a long time to the free air; it absorbs oxygen from the air, and becomes fully oxygenated.

As phosphorus has a sufficient affinity for oxygen to attract it from the nitric and muriatic acids, we may form phosphoric acid, by means of these acids, in a very simple and cheap manner. Fill a tubulated receiver, half full of concentrated nitric acid, and heat it gently, then throw in small pieces of phosphorus through the tube, these are dissolved with effervescence and red fumes of nitrous gas fly off; add phosphorus so long as it will dissolve, and then increase the fire under the retort to drive off the last particles of nitric acid; phosphoric acid, partly fluid and partly concrete, remains in the retort.

TABLE _of the Combinations of Carbonic Acid, with the Salifiable Bases, in the Order of Affinity._

_Names of_ _Resulting Neutral Salts._ _Bases_ _New Nomenclature._ _Old Nomenclature._

Barytes Carbonates of barytes(A) Aërated or effervescent heavy earth.

Lime lime {Chalk, calcareous spar, { Aërated calcareous earth.

Potash potash {Effervescing or aërated fixe { vegetable alkali, mephitis of { potash.

Soda soda {Aërated or effervescing fixed mineral { alkali, mephitic soda.

Magnesia magnesia {Aërated, effervescing, mild, or { mephitic magnesia.

Ammoniac ammoniac {Aërated, effervescing, mild, or { mephitic volatile alkali.

Argill argill {Aërated or effervescing argillaceous { earth, or earth of alum.

Oxyds of zinc zinc Zinc spar, mephitic or aërated zinc. iron iron Sparry iron-ore, mephitic or aërated iron. manganese manganese Aërated manganese. cobalt cobalt Aërated cobalt. nickel nickel Aërated nickel. lead lead Sparry lead-ore, or aërated lead. tin tin Aërated tin. copper copper Aërated copper. bismuth bismuth Aërated bismuth. antimony antimony Aërated antimony. arsenic arsenic Aërated arsenic. mercury mercury Aërated mercury. silver silver Aërated silver. gold gold Aërated gold. platina platina Aërated platina.

[Note A: As these salts have only been understood of late, they have not, properly speaking, any old names. Mr Morveau, in the First Volume of the Encyclopedia, calls them _Mephites_; Mr Bergman gives them the name of _aërated_; and Mr de Fourcroy, who calls the carbonic acid _chalky acid_, gives them the name of _chalks_.--A]

SECT. XVII.--_Observations upon Carbonic Acid, and its Combinations._

Of all the known acids, the carbonic is the most abundant in nature; it exists ready formed in chalk, marble, and all the calcareous stones, in which it is neutralized by a particular earth called _lime_. To disengage it from this combination, nothing more is requisite than to add some sulphuric acid, or any other which has a stronger affinity for lime; a brisk effervescence ensues, which is produced by the disengagement of the carbonic acid which assumes the state of gas immediately upon being set free. This gas, incapable of being condensed into the solid or liquid form by any degree of cold or of pressure hitherto known, unites to about its own bulk of water, and thereby forms a very weak acid. It may likewise be obtained in great abundance from saccharine matter in fermentation, but is then contaminated by a small portion of alkohol which it holds in solution.

As charcoal is the radical of this acid, we may form it artificially, by burning charcoal in oxygen gas, or by combining charcoal and metallic oxyds in proper proportions; the oxygen of the oxyd combines with the charcoal, forming carbonic acid gas, and the metal being left free, recovers its metallic or reguline form.

We are indebted for our first knowledge of this acid to Dr Black, before whose time its property of remaining always in the state of gas had made it to elude the researches of chemistry.

It would be a most valuable discovery to society, if we could decompose this gas by any cheap process, as by that means we might obtain, for economical purposes, the immense store of charcoal contained in calcareous earths, marbles, limestones, &c. This cannot be effected by single affinity, because, to decompose the carbonic acid, it requires a substance as combustible as charcoal itself, so that we should only make an exchange of one combustible body for another not more valuable; but it may possibly be accomplished by double affinity, since this process is so readily performed by Nature, during vegetation, from the most common materials.

TABLE _of the Combinations of Muriatic Acid, with the Salifiable Bases, in the Order of Affinity._

_Names of the_ _Resulting Neutral Salts._ _bases._ _New nomenclature._ _Old nomenclature._

Barytes. Muriat of {Sea-salt, having base of barytes { heavy earth.

Potash potash {Febrifuge salt of Sylvius: { Muriated vegetable fixed { alkali.

Soda soda Sea-salt. Lime lime Muriated lime. Oil of lime. Magnesia magnesia {Marine Epsom salt. Muriated magnesia. Ammoniac ammoniac Sal ammoniac.

Argill argill {Muriated alum, sea-salt { with base of earth of alum. Oxyd of zinc zinc Sea-salt of, or muriatic zinc. iron iron Salt of iron, Martial sea-salt. manganese manganese Sea-salt of manganese. cobalt cobalt Sea-salt of cobalt. nickel nickel Sea-salt of nickel. lead lead Horny-lead. Plumbum corneum. tin smoaking of tin Smoaking liquor of Libavius. solid of tin Solid butter of tin. copper copper Sea-salt of copper. bismuth bismuth Sea-salt of bismuth. antimony antimony Sea-salt of antimony. arsenic arsenic Sea-salt of arsenic.

{sweet of mercury {Sweet sublimate of mercury, { { calomel, aquila alba. mercury { { {corrosive of {Corrosive sublimate of { mercury { mercury.

silver silver Horny silver, argentum corneum, luna cornea. gold gold Sea-salt of gold. platina platina Sea-salt of platina.

TABLE _Of the Combinations of Oxygenated Muriatic Acid, with the Salifiable Bases, in the Order of Affinity._

_Names of the Neutral Salts by_ _Names of the Bases._ _the new Nomenclature._

Oxygenated muriat of Barytes barytes. Potash potash. Soda soda. Lime lime. Magnesia magnesia. Argill argill. Oxyd of zinc zinc. iron iron. manganese manganese. cobalt cobalt. nickel nickel. lead lead. tin tin. copper copper. bismuth bismuth. antimony antimony. arsenic arsenic. mercury mercury. silver silver. gold gold. platina platina.

This order of salts, entirely unknown to the ancient chemists, was discovered in 1786 by Mr Berthollet.--A.

SECT. XIX.--_Observations upon Muriatic and Oxygenated Muriatic Acids, and their Combinations._

Muriatic acid is very abundant in the mineral kingdom naturally combined with different salifiable bases, especially with soda, lime, and magnesia. In sea-water, and the water of several lakes, it is combined with these three bases, and in mines of rock-salt it is chiefly united to soda. This acid does not appear to have been hitherto decomposed in any chemical experiment; so that we have no idea whatever of the nature of its radical, and only conclude, from analogy with the other acids, that it contains oxygen as its acidifying principle. Mr Berthollet suspects the radical to be of a metallic nature; but, as Nature appears to form this acid daily, in inhabited places, by combining miasmata with aëriform fluids, this must necessarily suppose a metallic gas to exist in the atmosphere, which is certainly not impossible, but cannot be admitted without proof.

The muriatic acid has only a moderate adherence to the salifiable bases, and can readily be driven from its combination with these by sulphuric acid. Other acids, as the nitric, for instance, may answer the same purpose; but nitric acid being volatile, would mix, during distillation, with the muriatic. About one part of sulphuric acid is sufficient to decompose two parts of decrepitated sea-salt. This operation is performed in a tubulated retort, having Woulfe's apparatus, (Pl. IV. Fig. 1.), adapted to it. When all the junctures are properly lured, the sea-salt is put into the retort through the tube, the sulphuric acid is poured on, and the opening immediately closed with its ground crystal stopper. As the muriatic acid can only subsist in the gaseous form in the ordinary temperature, we could not condense it without the presence of water. Hence the use of the water with which the bottles in Woulfe's apparatus are half filled; the muriatic acid gas, driven off from the sea-salt in the retort, combines with the water, and forms what the old chemists called _smoaking spirit of salt_, or _Glauber's spirit of sea-salt_, which we now name _muriatic acid_.

The acid obtained by the above process is still capable of combining with a farther dose of oxygen, by being distilled from the oxyds of manganese, lead, or mercury, and the resulting acid, which we name _oxygenated muriatic acid_, can only, like the former, exist in the gasseous form, and is absorbed, in a much smaller quantity by water. When the impregnation of water with this gas is pushed beyond a certain point, the superabundant acid precipitates to the bottom of the vessels in a concrete form. Mr Berthollet has shown that this acid is capable of combining with a great number of the salifiable bases; the neutral salts which result from this union are susceptible of deflagrating with charcoal, and many of the metallic substances; these deflagrations are very violent and dangerous, owing to the great quantity of caloric which the oxygen carries alongst with it into the composition of oxygenated muriatic acid.

TABLE _of the Combinations of Nitro-muriatic Acid with the Salifiable Bases, in the Order of Affinity, so far as is known._

_Names of the Bases._ _Names of the Neutral Salts._

Argill Nitro-muriat of argill. Ammoniac ammoniac. Oxyd of antimony antimony. silver silver. arsenic arsenic. Barytes barytes. Oxyd of bismuth bismuth. Lime lime. Oxyd of cobalt cobalt. copper copper. tin tin. iron iron. Magnesia magnesia. Oxyd of manganese manganese. mercury mercury. molybdena molybdena. nickel nickel. gold gold. platina platina. lead lead. Potash potash. Soda soda. Oxyd of tungstein tungstein. zinc zinc.

_Note._--Most of these combinations, especially those with the earths and alkalies, have been little examined, and we are yet to learn whether they form a mixed salt in which the compound radical remains combined, or if the two acids separate, to form two distinct neutral salts.--A.

SECT. XX.--_Observations upon the Nitro-Muriatic Acid, and its Combinations._

The nitro-muriatic acid, formerly called _aqua regia_, is formed by a mixture of nitric and muriatic acids; the radicals of these two acids combine together, and form a compound base, from which an acid is produced, having properties peculiar to itself, and distinct from those of all other acids, especially the property of dissolving gold and platina.

In dissolutions of metals in this acid, as in all other acids, the metals are first oxydated by attracting a part of the oxygen from the compound radical. This occasions a disengagement of a particular species of gas not hitherto described, which may be called _nitro-muriatic gas_; it has a very disagreeable smell, and is fatal to animal life when respired; it attacks iron, and causes it to rust; it is absorbed in considerable quantity by water, which thereby acquires some slight characters of acidity. I had occasion to make these remarks during a course of experiments upon platina, in which I dissolved a considerable quantity of that metal in nitro-muriatic acid.

I at first suspected that, in the mixture of nitric and muriatic acids, the latter attracted a part of the oxygen from the former, and became converted into oxygenated muriatic acid, which gave it the property of dissolving gold; but several facts remain inexplicable upon this supposition. Were it so, we must be able to disengage nitrous gas by heating this acid, which however does not sensibly happen. From these considerations, I am led to adopt the opinion of Mr Berthollet, and to consider nitro-muriatic acid as a single acid, with a compound base or radical.

TABLE _of the Combinations of Fluoric Acid, with the Salifiable Bases, in the Order of Affinity._

_Names of the Bases._ _Names of the Neutral Salts._

Lime Fluat of lime. Barytes barytes. Magnesia magnesia. Potash potash. Soda soda. Ammoniac ammoniac. Oxyd of zinc zinc. manganese manganese. iron iron. lead lead. tin tin. cobalt cobalt. copper copper. nickel nickel. arsenic arsenic. bismuth bismuth. mercury mercury. silver silver. gold gold. platina platina.

And by the dry way, Argill Fluat of argill.

_Note._--These combinations were entirely unknown to the old chemists, and consequently have no names in the old nomenclature.--A.

SECT. XXI.--_Observations upon the Fluoric Acid, and its Combinations._

Fluoric exists ready formed by Nature in the fluoric spars[42], combined with calcareous earth, so as to form an insoluble neutral salt. To obtain it disengaged from that combination, fluor spar, or fluat of lime, is put into a leaden retort, with a proper quantity of sulphuric acid, a recipient likewise of lead, half full of water, is adapted, and fire is applied to the retort. The sulphuric acid, from its greater affinity, expels the fluoric acid which passes over and is absorbed by the water in the receiver. As fluoric acid is naturally in the gasseous form in the ordinary temperature, we can receive it in a pneumato-chemical apparatus over mercury. We are obliged to employ metallic vessels in this process, because fluoric acid dissolves glass and silicious earth, and even renders these bodies volatile, carrying them over with itself in distillation in the gasseous form.

We are indebted to Mr Margraff for our first acquaintance with this acid, though, as he could never procure it free from combination with a considerable quantity of silicious earth, he was ignorant of its being an acid sui generis. The Duke de Liancourt, under the name of Mr Boulanger, considerably increased our knowledge of its properties; and Mr Scheele seems to have exhausted the subject. The only thing remaining is to endeavour to discover the nature of the fluoric radical, of which we cannot hitherto form any ideas, as the acid does not appear to have been decomposed in any experiment. It is only by means of compound affinity that experiments ought to be made with this view, with any probability of success.

TABLE _of the Combinations of Boracic Acid, with the Salifiable Bases, in the Order of Affinity._

_Bases._ _Neutral Salts._

Lime Borat of lime. Barytes barytes. Magnesia magnesia. Potash potash. Soda soda. Ammoniac ammoniac. Oxyd of zinc zinc. iron iron. lead lead. tin tin. cobalt cobalt. copper copper. nickel nickel. mercury mercury. Argill argill.

_Note._--Most of these combinations were neither known nor named by the old chemists. The boracic acid was formerly called _sedative salt_, and its compounds _borax_, with base of fixed vegetable alkali, &c.--A.

SECT. XXII.--_Observations upon Boracic Add and its Combinations._

This is a concrete acid, extracted from a salt procured from India called _borax_ or _tincall_. Although borax has been very long employed in the arts, we have as yet very imperfect knowledge of its origin, and of the methods by which it is extracted and purified; there is reason to believe it to be a native salt, found in the earth in certain parts of the east, and in the water of some lakes. The whole trade of borax is in the hands of the Dutch, who have been exclusively possessed of the art of purifying it till very lately, that Messrs L'Eguillier of Paris have rivalled them in the manufacture; but the process still remains a secret to the world.

By chemical analysis we learn that borax is a neutral salt with excess of base, consisting of soda, partly saturated with a peculiar acid long called _Homberg's sedative salt_, now _the boracic acid_. This acid is found in an uncombined state in the waters of certain lakes. That of Cherchiais in Italy contains 94-1/2 grains in each pint of water.

To obtain boracic acid, dissolve some borax in boiling water, filtrate the solution, and add sulphuric acid, or any other having greater affinity to soda than the boracic acid; this latter acid is separated, and is procured in a crystalline form by cooling. This acid was long considered as being formed during the process by which it is obtained, and was consequently supposed to differ according to the nature of the acid employed in separating it from the soda; but it is now universally acknowledged that it is identically the same acid, in whatever way procured, provided it be properly purified from mixture of other acids, by warning, and by repeated solution and cristallization. It is soluble both in water and alkohol, and has the property of communicating a green colour to the flame of that spirit. This circumstance led to a suspicion of its containing copper, which is not confirmed by any decisive experiment. On the contrary, if it contain any of that metal, it must only be considered as an accidental mixture. It combines with the salifiable bases in the humid way; and though, in this manner, it is incapable of dissolving any of the metals directly, this combination is readily affected by compound affinity.

The Table presents its combinations in the order of affinity in the humid way; but there is a considerable change in the order when we operate via sicca; for, in that case, argill, though the last in our list, must be placed immediately after soda.

The boracic radical is hitherto unknown; no experiments having as yet been able to decompose the acid; We conclude, from analogy with the other acids, that oxygen exists in its composition as the acidifying principle.

TABLE _of the Combinations of Arseniac Acid, with the Salifiable Bases, in the Order of Affinity._

_Bases._ _Neutral Salts._

Lime Arseniat of lime. Barytes barytes. Magnesia magnesia. Potash potash. Soda soda. Ammoniac ammoniac. Oxyd of zinc zinc. manganese manganese. iron iron. lead lead. tin tin. cobalt cobalt. copper copper. nickel nickel. bismuth bismuth. mercury mercury. antimony antimony. silver silver. gold gold. platina platina. Argill argill.

_Note._--This order of salts was entirely unknown to the antient chemists. Mr Macquer, in 1746, discovered the combinations of arseniac acid with potash and soda, to which he gave the name of _arsenical neutral salts_.--A.

SECT. XXIII.--_Observations upon Arseniac Acid, and its Combinations._

In the Collections of the Academy for 1746, Mr Macquer shows that, when a mixture of white oxyd of arsenic and nitre are subjected to the action of a strong fire, a neutral salt is obtained, which he calls _neutral salt of arsenic_. At that time, the cause of this singular phenomenon, in which a metal acts the part of an acid, was quite unknown; but more modern experiments teach that, during this process, the arsenic becomes oxygenated, by carrying off the oxygen of the nitric acid; it is thus converted into a real acid, and combines with the potash. There are other methods now known for oxygenating arsenic, and obtaining its acid free from combination. The most simple and most effectual of these is as follows: Dissolve white oxyd of arsenic in three parts, by weight, of muriatic acid; to this solution, in a boiling state, add two parts of nitric acid, and evaporate to dryness. In this process the nitric acid is decomposed, its oxygen unites with the oxyd of arsenic, and converts it into an acid, and the nitrous radical flies off in the state of nitrous gas; whilst the muriatic acid is converted by the heat into muriatic acid gas, and may be collected in proper vessels. The arseniac acid is entirely freed from the other acids employed during the process by heating it in a crucible till it begins to grow red; what remains is pure concrete arseniac acid.

Mr Scheele's process, which was repeated with great success by Mr Morveau, in the laboratory at Dijon, is as follows: Distil muriatic acid from the black oxyd of manganese, this converts it into oxygenated muriatic acid, by carrying off the oxygen from the manganese, receive this in a recipient containing white oxyd of arsenic, covered by a little distilled water; the arsenic decomposes the oxygenated muriatic acid, by carrying off its supersaturation of oxygen, the arsenic is converted into arseniac acid, and the oxygenated muriatic acid is brought back to the state of common muriatic acid. The two acids are separated by distillation, with a gentle heat increased towards the end of the operation, the muriatic acid passes over, and the arseniac acid remains behind in a white concrete form.

The arseniac acid is considerably less volatile than white oxyd of arsenic; it often contains white oxyd of arsenic in solution, owing to its not being sufficiently oxygenated; this is prevented by continuing to add nitrous acid, as in the former process, till no more nitrous gas is produced. From all these observations I would give the following definition of arseniac acid. It is a white concrete metallic acid, formed by the combination of arsenic with oxygen, fixed in a red heat, soluble in water, and capable of combining with many of the salifiable bases.

SECT. XXIV.--_Observations upon Molybdic Acid, and its Combinations with Acidifiable Bases[43]._

Molybdena is a particular metallic body, capable of being oxygenated, so far as to become a true concrete acid[44]. For this purpose, one part ore of molybdena, which is a natural sulphuret of that metal, is put into a retort, with five or six parts nitric acid, diluted with a quarter of its weight of water, and heat is applied to the retort; the oxygen of the nitric acid acts both upon the molybdena and the sulphur, converting the one into molybdic, and the other into sulphuric acid; pour on fresh quantities of nitric acid so long as any red fumes of nitrous gas escape; the molydbena is then oxygenated as far as is possible, and is found at the bottom of the retort in a pulverulent form, resembling chalk. It must be washed in warm water, to separate any adhering particles of sulphuric acid; and, as it is hardly soluble, we lose very little of it in this operation. All its combinations with salifiable bases were unknown to the ancient chemists.

TABLE _of the Combinations of Tungstic Acid with the Salifiable Bases._

_Bases._ _Neutral Salts._

Lime Tungstat of lime. Barytes barytes. Magnesia magnesia. Potash potash. Soda soda. Ammoniac ammoniac. Argill argill. Oxyd of antimony(A), &c. antimony(B), &c.

[Note A: The combinations with metallic oxyds were set down by Mr Lavoisier in alphabetical order; their order of affinity being unknown, I have omitted them, as serving no purpose.--E.]

[Note B: All these salts were unknown to the ancient chemists.--A.]

SECT. XXV.--_Observations upon Tungstic Acid, and its Combinations._

Tungstein is a particular metal, the ore of which has frequently been confounded with that of tin. The specific gravity of this ore is to water as 6 to 1; in its form of cristallization it resembles the garnet, and varies in colour from a pearl-white to yellow and reddish; it is found in several parts of Saxony and Bohemia. The mineral called _Wolfram_, which is frequent in the mines of Cornwal, is likewise an ore of this metal. In all these ores the metal is oxydated; and, in some of them, it appears even to be oxygenated to the state of acid, being combined with lime into a true tungstat of lime.

To obtain the acid free, mix one part of ore of tungstein with four parts of carbonat of potash, and melt the mixture in a crucible, then powder and pour on twelve parts of boiling water, add nitric acid, and the tungstic acid precipitates in a concrete form. Afterwards, to insure the complete oxygenation of the metal, add more nitric acid, and evaporate to dryness, repeating this operation so long as red fumes of nitrous gas are produced. To procure tungstic acid perfectly pure, the fusion of the ore with carbonat of potash must be made in a crucible of platina, otherwise the earth of the common crucibles will mix with the products, and adulterate the acid.

TABLE _of the Combinations of Tartarous Acid, with the Salifiable Bases, in the Order of Affinity._

_Bases._ _Neutral Salts._

Lime Tartarite of lime. Barytes barytes. Magnesia magnesia. Potash potash. Soda soda. Ammoniac ammoniac. Argill argill. Oxyd of zinc zinc. iron iron. manganese manganese. cobalt cobalt. nickel nickel. lead lead. tin tin. copper copper. bismuth bismuth. antimony antimony. arsenic arsenic. silver silver. mercury mercury. gold gold. platina platina.

SECT. XXVI.--_Observations upon Tartarous Acid, and its Combinations._

Tartar, or the concretion which fixes to the inside of vessels in which the fermentation of wine is completed, is a well known salt, composed of a peculiar acid, united in considerable excess to potash. Mr Scheele first pointed out the method of obtaining this acid pure. Having observed that it has a greater affinity to lime than to potash, he directs us to proceed in the following manner. Dissolve purified tartar in boiling water, and add a sufficient quantity of lime till the acid be completely saturated. The tartarite of lime which is formed, being almost insoluble in cold water, falls to the bottom, and is separated from the solution of potash by decantation; it is afterwards washed in cold water, and dried; then pour on some sulphuric acid, diluted with eight or nine parts of water, digest for twelve hours in a gentle heat, frequently stirring the mixture; the sulphuric acid combines with the lime, and the tartarous acid is left free. A small quantity of gas, not hitherto examined, is disengaged during this process. At the end of twelve hours, having decanted off the clear liquor, wash the sulphat of lime in cold water, which add to the decanted liquor, then evaporate the whole, and the tartarous acid is obtained in a concrete form. Two pounds of purified tartar, by means of from eight to ten ounces of sulphuric acid, yield about eleven ounces of tartarous acid.

As the combustible radical exists in excess, or as the acid from tartar is not fully saturated with oxygen, we call it _tartarous acid_, and the neutral salts formed by its combinations with salifiable bases _tartarites_. The base of the tartarous acid is a carbono-hydrous or hydro-carbonous radical, less oxygenated than in the oxalic acid; and it would appear, from the experiments of Mr Hassenfratz, that azote enters into the composition of the tartarous radical, even in considerable quantity. By oxygenating the tartarous acid, it is convertible into oxalic, malic, and acetous acids; but it is probable the proportions of hydrogen and charcoal in the radical are changed during these conversions, and that the difference between these acids does not alone consist in the different degrees of oxygenation.

The tartarous acid is susceptible of two degrees of saturation in its combinations with the fixed alkalies; by one of these a salt is formed with excess of acid, improperly called _cream of tartar_, which in our new nomenclature is named _acidulous tartarite of potash_; by a second or equal degree of saturation a perfectly neutral salt is formed, formerly called _vegetable salt_, which we name _tartarite of potash_. With soda this acid forms tartarite of soda, formerly called _sal de Seignette_, or _sal polychrest of Rochell_.

SECT. XXVII.--_Observations upon Malic Acid, and its Combinations with the Salifiable Bases[45]._

The malic acid exists ready formed in the sour juice of ripe and unripe apples, and many other fruits, and is obtained as follows: Saturate the juice of apples with potash or soda, and add a proper proportion of acetite of lead dissolved in water; a double decomposition takes place, the malic acid combines with the oxyd of lead and precipitates, being almost insoluble, and the acetite of potash or soda remains in the liquor. The malat of lead being separated by decantation, is washed with cold water, and some dilute sulphuric acid is added; this unites with the lead into an insoluble sulphat, and the malic acid remains free in the liquor.

This acid, which is found mixed with citric and tartarous acid in a great number of fruits, is a kind of medium between oxalic and acetous acids being more oxygenated than the former, and less so than the latter. From this circumstance, Mr Hermbstadt calls it _imperfect vinegar_; but it differs likewise from acetous acid, by having rather more charcoal, and less hydrogen, in the composition of its radical.

When an acid much diluted has been used in the foregoing process, the liquor contains oxalic as well as malic acid, and probably a little tartarous, these are separated by mixing lime-water with the acids, oxalat, tartarite, and malat of lime are produced; the two former, being insoluble, are precipitated, and the malat of lime remains dissolved; from this the pure malic acid is separated by the acetite of lead, and afterwards by sulphuric acid, as directed above.

TABLE _of the Combinations of Citric Acid, with the Salifiable Bases, in the Order of Affinity(A)._

_Bases._ _Neutral Salts._

Barytes Citrat of barytes. Lime lime. Magnesia magnesia. Potash potash. Soda soda. Ammoniac ammoniac. Oxyd of zinc zinc. manganese manganese. iron iron. lead lead. cobalt cobalt. copper copper. arsenic arsenic. mercury mercury. antimony antimony. silver silver. gold gold. platina platina. Argill argill.

[Note A: These combinations were unknown to the ancient chemists. The order of affinity of the salifiable bases with this acid was determined by Mr Bergman and by Mr de Breney of the Dijon Academy.--A.]

SECT. XXVIII.--_Observations upon Citric Acid, and its Combinations._

The citric acid is procured by expression from lemons, and is found in the juices of many other fruits mixed with malic acid. To obtain it pure and concentrated, it is first allowed to depurate from the mucous part of the fruit by long rest in a cool cellar, and is afterwards concentrated by exposing it to the temperature of 4 or 5 degrees below Zero, from 21° to 23° of Fahrenheit, the water is frozen, and the acid remains liquid, reduced to about an eighth part of its original bulk. A lower degree of cold would occasion the acid to be engaged amongst the ice, and render it difficultly separable. This process was pointed out by Mr Georgius.

It is more easily obtained by saturating the lemon-juice with lime, so as to form a citrat of lime, which is insoluble in water; wash this salt, and pour on a proper quantity of sulphuric acid; this forms a sulphat of lime, which precipitates and leaves the citric acid free in the liquor.

TABLE _of the Combinations of Pyro-lignous Acid with the Salifiable Bases, in the Order of Affinity(A)._

_Bases._ _Neutral Salts._

Lime Pyro-mucite of lime. Barytes barytes. Potash potash. Soda soda. Magnesia magnesia. Ammoniac ammoniac. Oxyd of zinc zinc. manganese manganese. iron iron. lead lead. tin tin. cobalt cobalt. copper copper. nickel nickel. arsenic arsenic. bismuth bismuth. mercury mercury. antimony antimony. silver silver. gold gold. platina platina. Argill argill.

[Note A: The above affinities were determined by Messrs de Morveau and EloI Boursier de Clervaux. These combinations were entirely unknown till lately.--A.]

SECT. XXIX.--_Observations upon Pyro-lignous Acid, and its Combinations._

The ancient chemists observed that most of the woods, especially the more heavy and compact ones, gave out a particular acid spirit, by distillation, in a naked fire; but, before Mr Goetling, who gives an account of his experiments upon this subject in Crell's Chemical Journal for 1779, no one had ever made any inquiry into its nature and properties. This acid appears to be the same, whatever be the wood it is procured from. When first distilled, it is of a brown colour, and considerably impregnated with charcoal and oil; it is purified from these by a second distillation. The pyro-lignous radical is chiefly composed of hydrogen and charcoal.

SECT. XXX.--_Observations upon Pyro-tartarous Acid, and its Combinations with the Salifiable Bases[46]._

The name of _Pyro-tartarous acid_ is given to a dilute empyreumatic acid obtained from purified acidulous tartarite of potash by distillation in a naked fire. To obtain it, let a retort be half filled with powdered tartar, adapt a tubulated recipient, having a bent tube communicating with a bell-glass in a pneumato-chemical apparatus; by gradually raising the fire under the retort, we obtain the pyro-tartarous acid mixed with oil, which is separated by means of a funnel. A vast quantity of carbonic acid gas is disengaged during the distillation. The acid obtained by the above process is much contaminated with oil, which ought to be separated from it. Some authors advise to do this by a second distillation; but the Dijon academicians inform us, that this is attended with great danger from explosions which take place during the process.

TABLE _of the Combinations of Pyro-mucous Acid, with the Salifiable Bases, in the Order of Affinity(A)._

_Bases._ _Neutral Salts._

Potash Pyro-mucite of potash. Soda soda. Barytes barytes. Lime lime. Magnesia magnesia. Ammoniac ammoniac. Argill argill. Oxyd of zinc zinc. manganese manganese. iron iron. lead lead. tin tin. cobalt cobalt. copper copper. nickel nickel. arsenic arsenic. bismuth bismuth. antimony antimony.

[Note A: All these combinations were unknown to the ancient chemists.--A.]

SECT. XXXI.--_Observations upon Pyro-mucous Acid, and its Combinations._

This acid is obtained by distillation in a naked fire from sugar, and all the saccharine bodies; and, as these substances swell greatly in the fire, it is necessary to leave seven-eighths of the retort empty. It is of a yellow colour, verging to red, and leaves a mark upon the skin, which will not remove but alongst with the epidermis. It may be procured less coloured, by means of a second distillation, and is concentrated by freezing, as is directed for the citric acid. It is chiefly composed of water and oil slightly oxygenated, and is convertible into oxalic and malic acids by farther oxygenation with the nitric acid.

It has been pretended that a large quantity of gas is disengaged during the distillation of this acid, which is not the case if it be conducted slowly, by means of moderate heat.

TABLE _of the Combinations of the Oxalic Acid, with the Salifiable Bases, in the Order of Affinity(A)._

_Bases._ _Neutral Salts._

Lime Oxalat of lime. Barytes barytes. Magnesia magnesia. Potash potash. Soda soda. Ammoniac ammoniac. Argill argill. Oxyd of zinc zinc. iron iron. manganese manganese. cobalt cobalt. nickel nickel. lead lead. copper copper. bismuth bismuth. antimony antimony. arsenic arsenic. mercury mercury. silver silver. gold gold. platina platina.

[Note A: All unknown to the ancient chemists.--A.]

SECT. XXXII.--_Observations upon Oxalic Acid, and its Combinations._

The oxalic acid is mostly prepared in Switzerland and Germany from the expressed juice of sorrel, from which it cristallizes by being left long at rest; in this state it is partly saturated with potash, forming a true acidulous oxalat of potash, or salt with excess of acid. To obtain it pure, it must be formed artificially by oxygenating sugar, which seems to be the true oxalic radical. Upon one part of sugar pour six or eight parts of nitric acid, and apply a gentle heat; a considerable effervescence takes place, and a great quantity of nitrous gas is disengaged; the nitric acid is decomposed, and its oxygen unites to the sugar: By allowing the liquor to stand at rest, cristals of pure oxalic acid are formed, which must be dried upon blotting paper, to separate any remaining portions of nitric acid; and, to ensure the purity of the acid, dissolve the cristals in distilled water, and cristallize them afresh.

+---------------+------------------+--------------------------------------- | _Bases._ | _Neutral salts._ |_Names of the resulting neutral salts_ | | | |_according to the old nomenclature._ | |---------------+------------------+---------------------------------------+ |Barytes |Acetite of barytes{Unknown to the ancients. Discovered by | | | {Mr de Morveau, who calls it _barotic | | | {acéte_. | | | | | |Potash | ---- potash {Secret terra foliata tartari of Muller.| | | {Arcanum tartari of Basil Valentin and | | | {Paracelsus. Purgative magistery of | | | {tartar of Schroëder. Essential salt of | | | {wine of Zwelfer. Regenerated tartar of | | | {Tachenius. Diuretic salt of Sylvius | | | {and Wilson. | | | | | |Soda | ---- soda {Foliated earth with base of mineral | | | {alkali. Mineral or crystallisable | | | {foliated earth. Mineral acetous salt. | | | | | |Lime | ---- lime {Salt of chalk, coral, or crabs eyes; | | | {mentioned by Hartman. | | | | | |Magnesia | ---- magnesia |First mentioned by Mr Wenzel. | | | | | |Ammoniac | ---- ammoniac {Spiritus Mindereri. | | | {Ammoniacal acetous salt. | | | | | |Oxyd of zinc | ---- zinc {Known to Glauber, Schwedemberg, | | | {Respour, Pott, de Lassone, and Wenzel, | | | {but not named. | | | | | | ---- manganese| ---- manganese |Unknown to the ancients. | | | | | | ---- iron | ---- iron {Martial vinegar. Described by Monnet, | | | {Wenzel, and the Duke d'Ayen. | | | | | | ---- lead | ---- lead {Sugar, vinegar, and salt of lead or | | | {Saturn. | | | | | | ---- tin | ---- tin {Known to Lemery, Margraff, Monnet, | | | {Weslendorf, and Wenzel, but not named. | | | | | | ---- cobalt | ---- cobalt |Sympathetic ink of Mr Cadet. | | | | | | ---- copper | ---- copper {Verdigris, crystals of verditer, | | | {verditer, distilled verdigris, crystals| | | {of Venus or of copper. | | | | | | ---- nickel | ---- nickel |Unknown to the ancients. | | | | | | ---- arsenic | ---- arsenic {Arsenico-acetous fuming liquor, | | | {liquid phosphorus of Mr Cadet. | | | | | | ---- bismuth | ---- bismuth {Sugar of bismuth of Mr Geoffroi. Known | | | {to Gellert, Pott, Weslendorf, Bergman, | | | {and de Morveau. | | | | | | ---- mercury | ---- mercury {Mercurial foliated earth, Keyser's | | | {famous antivenereal remedy. Mentioned | | | {by Gebaver in 1748; known to Helot, | | | {Margraff, Baumé, Bergman, and | | | {de Morveau. | | | | | | ---- antimony | ---- antimony |Unknown. | | | | | | ---- silver | ---- silver {Described by Margraff, Monnet, and | | | {Wenzel; unknown to the ancients. | | | | | | ---- gold | ---- gold {Little known, mentioned by Schroëder | | | {and Juncker. | | | | | | ---- platina | ---- platina |Unknown. | | | | | |Argill | ---- argill |According to Mr Wenzel, vinegar | | | |dissolves only a very small proportion | | | |of argill. | +---------------+------------------+---------------------------------------+

From the liquor remaining after the first cristallization of the oxalic acid we may obtain malic acid by refrigeration: This acid is more oxygenated than the oxalic; and, by a further oxygenation, the sugar is convertible into acetous acid, or vinegar.

The oxalic acid, combined with a small quantity of soda or potash, has the property, like the tartarous acid, of entering into a number of combinations without suffering decomposition: These combinations form triple salts, or neutral salts with double bases, which ought to have proper names. The salt of sorrel, which is potash having oxalic acid combined in excess, is named acidulous oxalat of potash in our new nomenclature.

The acid procured from sorrel has been known to chemists for more than a century, being mentioned by Mr Duclos in the Memoirs of the Academy for 1688, and was pretty accurately described by Boerhaave; but Mr Scheele first showed that it contained potash, and demonstrated its identity with the acid formed by the oxygenation of sugar.

SECT. XXXIII.--_Observations upon Acetous Acid, and its Combinations._

This acid is composed of charcoal and hydrogen united together, and brought to the state of an acid by the addition of oxygen; it is consequently formed by the same elements with the tartarous oxalic, citric, malic acids, and others, but the elements exist in different proportions in each of these; and it would appear that the acetous acid is in a higher state of oxygenation than these other acids. I have some reason to believe that the acetous radical contains a small portion of azote; and, as this element is not contained in the radicals of any vegetable acid except the tartarous, this circumstance is one of the causes of difference. The acetous acid, or vinegar, is produced by exposing wine to a gentle heat, with the addition of some ferment: This is usually the ley, or mother, which has separated from other vinegar during fermentation, or some similar matter. The spiritous part of the wine, which consists of charcoal and hydrogen, is oxygenated, and converted into vinegar: This operation can only take place with free access of air, and is always attended by a diminution of the air employed in consequence of the absorption of oxygen; wherefore, it ought always to be carried on in vessels only half filled with the vinous liquor submitted to the acetous fermentation. The acid formed during this process is very volatile, is mixed with a large proportion of water, and with many foreign substances; and, to obtain it pure, it is distilled in stone or glass vessels by a gentle fire. The acid which passes over in distillation is somewhat changed by the process, and is not exactly of the same nature with what remains in the alembic, but seems less oxygenated: This circumstance has not been formerly observed by chemists.

Distillation is not sufficient for depriving this acid of all its unnecessary water; and, for this purpose, the best way is by exposing it to a degree of cold from 4° to 6° below the freezing point, from 19° to 23° of Fahrenheit; by this means the aqueous part becomes frozen, and leaves the acid in a liquid state, and considerably concentrated. In the usual temperature of the air, this acid can only exist in the gasseous form, and can only be retained by combination with a large proportion of water. There are other chemical processes for obtaining the acetous acid, which consist in oxygenating the tartarous, oxalic, or malic acids, by means of nitric acid; but there is reason to believe the proportions of the elements of the radical are changed during this process. Mr Hassenfratz is at present engaged in repeating the experiments by which these conversions are said to be produced.

The combinations of acetous acid with the various salifiable bases are very readily formed; but most of the resulting neutral salts are not cristallizable, whereas those produced by the tartarous and oxalic acids are, in general, hardly soluble. Tartarite and oxalat of lime are not soluble in any sensible degree: The malats are a medium between the oxalats and acetites, with respect to solubility, and the malic acid is in the middle degree of saturation between the oxalic and acetous acids. With this, as with all the acids, the metals require to be oxydated previous to solution.

The ancient chemists knew hardly any of the salts formed by the combinations of acetous acid with the salifiable bases, except the acetites of potash, soda, ammoniac, copper, and lead. Mr Cadet discovered the acetite of arsenic[47]; Mr Wenzel, the Dijon academicians Mr de Lassone, and Mr Proust, made us acquainted with the properties of the other acetites. From the property which acetite of potash possesses, of giving out ammoniac in distillation, there is some reason to suppose, that, besides charcoal and hydrogen, the acetous radical contains a small proportion of azote, though it is not impossible but the above production of ammoniac may be occasioned by the decomposition of the potash.

TABLE _of the Combinations of Acetic Acid with the Salifiable Bases, in the order of affinity._

_Bases._ _Neutral Salts._

Barytes Acetat of barytes. Potash potash. Soda soda. Lime lime. Magnesia magnesia. Ammoniac ammoniac. Oxyd of zinc zinc. manganese manganese. iron iron. lead lead. tin tin. cobalt cobalt. copper copper. nickel nickel. arsenic arsenic. bismuth bismuth. mercury mercury. antimony antimony. silver silver. gold gold. platina platina. Argill argill.

_Note._--All these salts were unknown to the ancients; and even those chemists who are most versant in modern discoveries, are yet at a lose whether the greater part of the salts produced by the oxygenated acetic radical belong properly to the class of acetites, or to that of acetats.--A.

SECT. XXXIV.--_Observations upon Acetic Acid, and its Combinations._

We have given to radical vinegar the name of acetic acid, from supposing that it consists of the same radical with that of the acetous acid, but more highly saturated with oxygen. According to this idea, acetic acid is the highest degree of oxygenation of which the hydro-carbonous radical is susceptible; but, although this circumstance be extremely probable, it requires to be confirmed by farther, and more decisive experiments, before it be adopted as an absolute chemical truth. We procure this acid as follows: Upon three parts acetite of potash or of copper, pour one part of concentrated sulphuric acid, and, by distillation, a very highly concentrated vinegar is obtained, which we call acetic acid, formerly named radical vinegar. It is not hitherto rigorously proved that this acid is more highly oxygenated than the acetous acid, nor that the difference between them may not consist in a different proportion between the elements of the radical or base.

TABLE _of the Combinations of Succinic Acid with the Salifiable Bases, in the order of Affinity._

_Bases._ _Neutral Salts._

Barytes Succinat of barytes. Lime lime. Potash potash. Soda soda. Ammoniac ammoniac. Magnesia magnesia. Argill argill. Oxyd of zinc zinc. iron iron. manganese manganese. cobalt cobalt. nickel nickel. lead lead. tin tin. copper copper. bismuth bismuth. antimony antimony. arsenic arsenic. mercury mercury. silver silver. gold gold. platina platina.

_Note._--All the succinats were unknown to the ancient chemists.--A.

SECT. XXXV.--_Observations upon Succinic Acid, and its Combinations._

The succinic acid is drawn from amber by sublimation in a gentle heat, and rises in a concrete form into the neck of the subliming vessel. The operation must not be pushed too far, or by too strong a fire, otherwise the oil of the amber rises alongst with the acid. The salt is dried upon blotting paper, and purified by repeated solution and crystallization.

This acid is soluble in twenty-four times its weight of cold water, and in a much smaller quantity of hot water. It possesses the qualities of an acid in a very small degree, and only affects the blue vegetable colours very slightly. The affinities of this acid, with the salifiable bases, are taken from Mr de Morveau, who is the first chemist that has endeavoured to ascertain them.

SECT. XXXVI.--_Observations upon Benzoic Acid, and its Combinations with Salifiable Bases[48]._

This acid was known to the ancient chemists under the name of Flowers of Benjamin, or of Benzoin, and was procured, by sublimation, from the gum or resin called Benzoin: The means of procuring it, _via humida_, was discovered by Mr Geoffroy, and perfected by Mr Scheele. Upon benzoin, reduced to powder, pour strong lime-water, having rather an excess of lime; keep the mixture continually stirring, and, after half an hour's digestion, pour off the liquor, and use fresh portions of lime-water in the same manner, so long as there is any appearance of neutralization. Join all the decanted liquors, and evaporate, as far as possible, without occasioning cristallization, and, when the liquor is cold, drop in muriatic acid till no more precipitate is formed. By the former part of the process a benzoat of lime is formed, and, by the latter, the muriatic acid combines with the lime, forming muriat of lime, which remains dissolved, while the benzoic acid, being insoluble, precipitates in a concrete state.

SECT. XXXVII.--_Observations upon Camphoric Acid, and its Combinations with Salifiable Bases[49]._

Camphor is a concrete essential oil, obtained, by sublimation, from a species of laurus which grows in China and Japan. By distilling nitric acid eight times from camphor, Mr Kosegarten converted it into an acid analogous to the oxalic; but, as it differs from that acid in some circumstances, we have thought necessary to give it a particular name, till its nature be more completely ascertained by farther experiment.

As camphor is a carbono-hydrous or hydro-carbonous radical, it is easily conceived, that, by oxygenation, it should form oxalic, malic, and several other vegetable acids: This conjecture is rendered not improbable by the experiments of Mr Kosegarten; and the principal phenomena exhibited in the combinations of camphoric acid with the salifiable bases, being very similar to those of the oxalic and malic acids, lead me to believe that it consists of a mixture of these two acids.

SECT. XXXVIII.--_Observations upon Gallic Acid, and its Combinations with Salifiable Bases[50]._

The Gallic acid, formerly called Principle of Astringency, is obtained from gall nuts, either by infusion or decoction with water, or by distillation with a very gentle heat. This acid has only been attended to within these few years. The Committee of the Dijon Academy have followed it through all its combinations, and give the best account of it hitherto produced. Its acid properties are very weak; it reddens the tincture of turnsol, decomposes sulphurets, and unites to all the metals when they have been previously dissolved in some other acid. Iron, by this combination, is precipitated of a very deep blue or violet colour. The radical of this acid, if it deserves the name of one, is hitherto entirely unknown; it is contained in oak willow, marsh iris, the strawberry, nymphea, Peruvian bark, the flowers and bark of pomgranate, and in many other woods and barks.

SECT. XXXIX.--_Observations upon Lactic Acid, and its Combinations with Salifiable Bases[51]._

The only accurate knowledge we have of this acid is from the works of Mr Scheele. It is contained in whey, united to a small quantity of earth, and is obtained as follows: Reduce whey to one eighth part of its bulk by evaporation, and filtrate, to separate all its cheesy matter; then add as much lime as is necessary to combine with the acid; the lime is afterwards disengaged by the addition of oxalic acid, which combines with it into an insoluble neutral salt. When the oxalat of lime has been separated by decantation, evaporate the remaining liquor to the consistence of honey; the lactic acid is dissolved by alkohol, which does not unite with the sugar of milk and other foreign matters; these are separated by filtration from the alkohol and acid; and the alkohol being evaporated, or distilled off, leaves the lactic acid behind.

This acid unites with all the salifiable bases forming salts which do not cristallize; and it seems considerably to resemble the acetous acid.

TABLE _of the Combinations of Saccholactic Acid with the Salifiable Bases, in the Order of Affinity._

_Bases._ _Neutral Salts._

Lime Saccholat of lime. Barytes barytes. Magnesia magnesia. Potash potash. Soda soda. Ammoniac ammoniac. Argill argill. Oxyd of zinc zinc. manganese manganese. iron iron. lead lead. tin tin. cobalt cobalt. copper copper. nickel nickel. arsenic arsenic. bismuth bismuth. mercury mercury. antimony antimony. silver silver.

_Note._--All these were unknown to the ancient chemists.--A.

SECT. XL.--_Observations upon Saccholactic Acid, and its Combinations._

A species of sugar may be extracted, by evaporation, from whey, which has long been known in pharmacy, and which has a considerable resemblance to that procured from sugar canes. This saccharine matter, like ordinary sugar, may be oxygenated by means of nitric acid: For this purpose, several portions of nitric acid are distilled from it; the remaining liquid is evaporated, and set to cristallize, by which means cristals of oxalic acid are procured; at the same time a very fine white powder precipitates, which is the saccholactic acid discovered by Scheele. It is susceptible of combining with the alkalies, ammoniac, the earths, and even with the metals: Its action upon the latter is hitherto but little known, except that, with them, it forms difficultly soluble salts. The order of affinity in the table is taken from Bergman.

TABLE _of the Combinations of Formic Acid, with the Salifiable Bases, in the Order of Affinity._

_Bases._ _Neutral Salts._

Barytes Formiat of barytes. Potash potash. Soda soda. Lime lime. Magnesia magnesia. Ammoniac ammoniac. Oxyd of zinc zinc. manganese manganese. iron iron. lead lead. tin tin. cobalt cobalt. copper copper. nickel nickel. bismuth bismuth. silver silver. Argill argill.

_Note._--All unknown to the ancient chemists.--A.

SECT. XLI.--_Observations upon Formic Acid, and its Combinations._

This acid was first obtained by distillation from ants, in the last century, by Samuel Fisher. The subject was treated of by Margraff in 1749, and by Messrs Ardwisson and Ochrn of Leipsic in 1777. The formic acid is drawn from a large species of red ants, _formica rufa, Lin._ which form large ant hills in woody places. It is procured, either by distilling the ants with a gentle heat in a glass retort or an alembic; or, after having washed the ants in cold water, and dried them upon a cloth, by pouring on boiling water, which dissolves the acid; or the acid may be procured by gentle expression from the insects, in which case it is stronger than in any of the former ways. To obtain it pure, we must rectify, by means of distillation, which separates it from the uncombined oily and charry matter; and it may be concentrated by freezing, in the manner recommended for treating the acetous acid.

SECT. XLII.--_Observations upon Bombic Acid, and its Combinations with Acidifiable Bases[52]._

The juices of the silk worm seem to assume an acid quality when that insect changes from a larva to a chrysalis. At the moment of its escape from the latter to the butterfly form, it emits a reddish liquor which reddens blue paper, and which was first attentively observed by Mr Chaussier of the Dijon academy, who obtains the acid by infusing silk worm chrysalids in alkohol, which dissolves their acid without being charged with any of the gummy parts of the insect; and, by evaporating the alkohol, the acid remains tollerably pure. The properties and affinities of this acid are not hitherto ascertained with any precision; and we have reason to believe that analogous acids may be procured from other insects. The radical of this acid is probably, like that of the other acids from the animal kingdom, composed of charcoal, hydrogen, and azote, with the addition, perhaps, of phosphorus.

TABLE _of the Combinations of Sebacic Acid, with the Salifiable Bases, in the Order of Affinity._

_Bases._ _Neutral Salts._

Barytes Sebat of barytes. Potash potash. Soda soda. Lime lime. Magnesia magnesia. Ammoniac ammoniac. Argill argill. Oxyd of zinc zinc. manganese manganese. iron iron. lead lead. tin tin. cobalt cobalt. copper copper. nickel nickel. arsenic arsenic. bismuth bismuth. mercury mercury. antimony antimony. silver silver.

_Note._--All these were unknown to the ancient chemists.--A.

SECT. XLIII.--_Observations upon Sebacid Acid, and its Combinations._

To obtain the sebacic acid, let some suet be melted in a skillet over the fire, alongst with some quick-lime in fine powder, and constantly stirred, raising the fire towards the end of the operation, and taking care to avoid the vapours, which are very offensive. By this process the sebacic acid unites with the lime into a sebat of lime, which is difficultly soluble in water; it is, however, separated from the fatty matters with which it is mixed by solution in a large quantity of boiling water. From this the neutral salt is separated by evaporation; and, to render it pure, is calcined, redissolved, and again cristallized. After this we pour on a proper quantity of sulphuric acid, and the sebacic acid passes over by distillation.

SECT. XLIV.--_Observations upon the Lithic Acid, and its Combinations with the Salifiable Bases[53]._

From the later experiments of Bergman and Scheele, the urinary calculus appears to be a species of salt with an earthy basis; it is slightly acidulous, and requires a large quantity of water for solution, three grains being scarcely soluble in a thousand grains of boiling water, and the greater part again cristallizes when cold. To this concrete acid, which Mr de Morveau calls Lithiasic Acid, we give the name of Lithic Acid, the nature and properties of which are hitherto very little known. There is some appearance that it is an acidulous neutral salt, or acid combined in excess with a salifiable base; and I have reason to believe that it really is an acidulous phosphat of lime; if so, it must be excluded from the class of peculiar acids.

TABLE _of the Combinations of the Prussic Acid with the Salifiable Bases, in the order of affinity._

_Bases._ _Neutral Salts._

Potash Prussiat of potash. Soda soda. Ammoniac ammoniac. Lime lime. Barytes barytes. Magnesia magnesia. Oxyd of zinc zinc. iron iron. manganese manganese. cobalt cobalt. nickel nickel. lead lead. tin tin. copper copper. bismuth bismuth. antimony antimony. arsenic arsenic. silver silver. mercury mercury. gold gold. platina platina.

_Note._---All these were unknown to former chemists.--A.

_Observations upon the Prussic Acid, and its Combinations._

As the experiments which have been made hitherto upon this acid seem still to leave a considerable degree of uncertainty with regard to its nature, I shall not enlarge upon its properties, and the means of procuring it pure and dissengaged from combination. It combines with iron, to which it communicates a blue colour, and is equally susceptible of entering into combination with most of the other metals, which are precipitated from it by the alkalies, ammoniac, and lime, in consequence of greater affinity. The Prussic radical, from the experiments of Scheele, and especially from those of Mr Berthollet, seems composed of charcoal and azote; hence it is an acid with a double base. The phosphorus which has been found combined with it appears, from the experiments of Mr Hassenfratz, to be only accidental.

Although this acid combines with alkalies, earths, and metals, in the same way with other acids, it possesses only some of the properties we have been in use to attribute to acids, and it may consequently be improperly ranked here in the class of acids; but, as I have already observed, it is difficult to form a decided opinion upon the nature of this substance until the subject has been farther elucidated by a greater number of experiments.

FOOTNOTES:

[36] See Memoirs of the Academy for 1776, p. 671. and for 1778, p. 535,--A.

[37] See Part I . Chap. XI. upon this subject.--A.

[38] See Part I . Chap. XI. upon the application of these names according to the proportions of the two ingredients.--A

[39] See