Part 15
The largest types or letters of 2 or 3 inches diameter are made of metal composed of 1 atom antimony and 3 of lead, or 40 parts to 270. This alloy also fuses about 450 or 460°, which is a very remarkable fact. Its specific gravity is usually 10.22. After several trials I could not determine whether the fusing point of this or the preceding alloy was lower; and equal parts of the two alloys fused together were liquified at the same temperature of 450 or 460°.
All the intermediate sizes of types appear to be made of one or other of the three preceding proportions or of mixtures of them, the smaller the type the more of antimony being required to give the requisite hardness. The largest types might, I conceive, be made with a much greater proportion of lead.
When 40 antimony and 360 lead (1 atom to 4) are fused together, the melting point is about 470°. The specific gravity was found 10.4, but probably too low from blisters or air bubbles. The alloy was more flexible than the preceding, but brittle with a fine grained fracture.
Forty parts antimony with 450 lead (1 atom to 5) fused at 490°, and gave 11 specific gravity. This alloy bends and breaks with a fine grained fracture.
Forty parts antimony with 540 lead (1 atom to 6) fused at 510°, and gave 10.8 specific gravity, which in all probability was owing to air bubbles. Now the alloy soft and malleable.
4. _Lead and arsenic._ When lead is fused in contact with the white oxide of arsenic under a film of tallow and stirred frequently, an union of the two metals takes place and the excess of white oxide is partially converted into arsenic and partly driven off, seemingly taking with it a portion of the lead. A considerable portion of the mass assumes the form of a black spongy compound infusible at the temperature. It contains a portion of the lead and is probably a compound of the metals with oxygen. The fusible alloy has the appearance of lead, but is brittle, breaks without bending and exhibits a fracture like that of antimony and lead. The specific gravity of the alloy is 10.6, or more if not saturated with lead. By treating it with an excess of nitric acid it is dissolved, and the lead may be thrown down by sulphuric acid, and the arsenic acid or oxide by lime. In this way I find the alloy is composed of about 9 parts of lead with 2 of arsenic, or 1 atom of each of the metals. The spongy mass treated with nitric acid yields a similar solution, accompanied with a precipitation of oxide of arsenic.
5. _Lead and cobalt._ The alloy of these two metals is not easily obtained, probably from the great difference of the temperature at which they fuse. Gmelin fused 1 part cobalt with 1, 2, 4, 6 and 8 parts of lead respectively. Alloys were obtained of the specific gravities 8.12, 12.28 (query 8.28?), --, 9.65 and 9.78 respectively. From these specific gravities it is plain the lead had been in great part dissipated by the heat. For the last or greatest specific gravity corresponds nearly to 2 parts lead and 1 of cobalt. (An. de Chimie, 19--357.)
_Triple Alloys, Solders; Fusible Metal, &c._
Though it may seem premature to treat of triple compounds in the present chapter, which professedly is limited to compounds of two elements, yet as the triple alloys are few and so immediately connected with the preceding, it will scarcely require an apology for introducing them here.
_Soft solders._ Solders for plumbers and tin-workers, are required to melt easily, and yet not too low, as they should withstand a heat greater than boiling water. The fusing point of the soft solders is usually between 300-400°. Plumbers’ solder I believe is commonly formed by mixing equal parts of tin and lead. I procured a specimen of 8.9 specific gravity, and its fusing point was 380°. Probably a more perfect compound would be formed by mixing 104 parts tin with 90 lead (2 atoms to 1), which would give a specific gravity of 8.8 and the fusing point 350°.
Tin workers’ solder is made rather more fusible than that of the plumbers. A specimen I got from the workmen was 8.87 specific gravity and fused at 345°. A mixture of 3 parts tin and 2 of lead would have formed an alloy of the same fusibility, but the specific gravity would have been 8.6 or 8.7 only. Probably a rather less proportion of tin with a little bismuth entered into the composition.
_Fusible Metal._ Tin, bismuth and lead are metals which melt at comparatively low temperatures; and it has been shewn that the alloys of any two of them usually melt at lower temperatures than the mean, or even than the lower extreme. By analogy it might be inferred that an alloy of tin and lead fused with one of tin and bismuth, would melt below either of the two ingredients. It has been shewn that proportions of bismuth and lead of easiest fusion are 2 atoms bismuth with one of lead; this alloy melts at 250°. An alloy of 2 atoms of bismuth and 1 of tin melts at 260°; and so does that of 1 atom bismuth and 1 tin. These alloys being much more easily fused than any other proportions of these metals, it is from their combinations we are to expect a still further reduction of the fusing point. In fact, a combination of either of the tin and bismuth alloys, with the lead and bismuth alloy, produces almost exactly the same reduction of the fusing temperature.
Thus if 4 atoms of bismuth, 1 of tin and 1 of lead be fused together, the compound melts in boiling water or below 212°. It is equally the case if 3 atoms bismuth, 1 of tin and 1 of lead, are fused together.
The double alloy next to those above mentioned in regard to easy fusion is that of 2 atoms tin, and 1 bismuth. It fuses at 320°. This alloy, united to the one of 2 atoms bismuth and 1 lead, gives a compound of 3 atoms bismuth, 2 tin and 1 lead, which fuses very nearly at the same temperature as the above triple alloys.
In reference to weights, the above proportions for the most fusible metals will nearly be,
Bismuth 14 parts -- Lead 5 -- tin 3 ------- 10 ----- -- ---- 5 ------ 3 ------- 5 ----- -- ---- 2½ ------ 3
Most of the elementary books have given the proportions of 8 bismuth, 5 lead and 3 tin; or 5 bismuth 2 lead and 3 tin, which nearly agree with some of the above, and give an alloy fusing below 212°.
Wishing to investigate this subject more fully, and it being obvious from the preceding facts that there are only two proportions of tin and lead to be united with bismuth, to produce the desired effect, namely, either 1 atom of tin with 1 of lead, or 2 atoms of tin with 1 of lead, I proceeded as follows:
1 atom tin (52) + 1 atom lead (90) + 1 atom bismuth (62), were fused together; the fusing point was 270°. The alloy was flexible to a certain degree; and the fracture very small grained. To this alloy 31 grains of bismuth were added successively till it was evident the alloy was growing less fusible; the results were as follows:
1 atom tin + 1 lead + 1 bismuth; fuses at 270° 1 -------- + 1 ---- + 1½ ------ -------- 235° 1 -------- + 1 ---- + 2 ------ -------- 205° 1 -------- + 1 ---- + 2½ ------ -------- 200° 1 -------- + 1 ---- + 3 ------ -------- 197° 1 -------- + 1 ---- + 3½ ------ -------- 200° 1 -------- + 1 ---- + 4 ------ -------- 220° 1 -------- + 1 ---- + 4½ ------ -------- 205° semi fluid. 1 -------- + 1 ---- + 5 ------ -------- 240° semi fluid. but it retains a little fluidity down to nearly 200°
From this it appears that 3 parts by weight of tin, 5 of lead, and any proportion of bismuth from 7 to 14 will produce an alloy fusing below 212°; but of these the best is 10 or 11 parts.
Again, 2 atoms of tin were combined with 1 of lead and 3 of bismuth, by gradually adding one half of the tin. The several alloys fused without any material difference at or below 200°. A further addition of tin impaired the property as in the above case with bismuth. I did not think it important to mix 2 atoms of tin and 1 of lead with any other proportion than 3 atoms of bismuth.
APPENDIX.
Since the publication of the second part of the first volume, (1810) some important essays on the subject of heat have appeared, which have a direct bearing upon some points of the doctrine on that subject inculcated in the said volume. It may be proper to state the results, with such remarks and reflections as have occurred in the consideration of them.
In the Annales de Chimie for January 1813, also in the Annals of Philosophy, vol. 2, we find a Memoir on the specific heat of different gases, by M. M. De la Roche and Berard. This exhibits a most laborious and refined series of experiments on this most difficult subject. Great merit seems to be due to them, both for invention and execution.
It is unnecessary to describe the particulars of the apparatus and the mode of conducting the experiments, as a description may be found as above referred. It is sufficient to observe that the _calorimeter_ used was a copper cylinder of 3 inches diameter and 6 in length, filled with water, and having a serpentine tube 5 feet in length, running through the interior and opening at both ends on the outside of the vessels. By means of this tube a regular current of any gas of a given temperature (212°) might be passed through the vessel so as to part with its excess of temperature to the water. The quantity of water and the capacity of the vessel for heat were previously determined; and the quantity of heated gas passed through the calorimeter was determinable at any time, as well as the temperature of the water, from the judicious arrangements.
It is easy to see that when an apparatus of this kind is at work, the gas will impart heat, more or less according to its capacity, to the water; and that the temperature of the calorimeter will gradually ascend till it arrives at a maximum; that is, till the refrigerating effect of the surrounding atmosphere upon the calorimeter is equal to the heating effect of the current of gas.
_The following Table exhibits the results of their experiments._
+----------------+---------------------------------------+ | | Specific Heat | | | Of the same bulk.| Of the same weight.| +----------------+------------------+--------------------+ | Air | 1.0000 | 1.0000 | | Hydrogen | 0.9033 | 12.3401 | | Carbonic Acid | 1.2583 | 0.8280 | | Oxygen | 0.9765 | 0.8848 | | Azote | 1.0000 | 1.0318 | | Nitrous Oxide | 1.3503 | 0.8878 | | Olefiant Gas | 1.5530 | 1.5763 | | Carbonic Oxide | 1.0340 | 1.0805 | | Aqueous Vapour | 1.9600 | 3.1360[24] | +----------------+------------------+--------------------+
[Footnote 24: The result for this last article must be considered more uncertain than any of the previous ones, the experiment being more complicated.]
They found the specific heats of equal volumes of air of the pressures 29.2 and 41.7 inches of mercury to be nearly as 1 ∶ 1.2396, differing from the ratio of the pressures or densities, which is 1: 1.358.
The above table of the specific heat of the permanent gases (excluding aqueous vapour) was corroborated by the results of another series of experiments in which the principle was varied a little: namely, to find how many cubic inches of each gas at a given temperature were required to raise the temperature of the calorimeter a given number of degrees, and inferring the capacities for heat to be inversely as the quantities of gas employed. The differences in the results were from 1 to 10 per cent., which may be considered small, in experiments of such delicacy.
The ratios of the specific heats of several gases being found, it was highly expedient to find the ratio of the specific heat of water, and that of some one gas, as common air. This was effected by passing a small current of hot water through the calorimeter, and comparing the effect of this current with that of the larger one of air, the requisite care being taken to ascertain the quantity of water passing in a given time and its temperature at the ingress. The result of this experiment was that the specific heat of water is to that of common air as 1 ∶ .25 nearly. By two other experiments, varied from the above, results not much differing were obtained, so that the average of the three gave, water to air, as 1 ∶ .2669.
Reducing the specific heats of the gases to the standard of water as unity, we have the following Table of the specific heats of equal weights of the respective bodies:
Water 1.0000 Air 0.2669 Hydrogen 3.2936 Carbonic Acid 0.2210 Oxygen 0.2361 Azote 0.2754 Nitrous Oxide 0.2369 Olefiant Gas 0.4207 Carbonic Oxide 0.2884 Aqueous Vapour 0.8474
Before we animadvert upon these results, it will be expedient to give an abstract of the not less interesting experiments of Messrs. Dulong and Petit, on heat, as given in the Annales de Chimie and de Physique, vol. 7 and 10.
These gentlemen begin by an investigation of the expansion of air by heat. The absolute expansion of air from freezing of water to boiling had been previously determined by Gay Lussac and myself to be from 8 to 11 nearly: they however extended the enquiry above and below these points of temperature, namely to those of freezing and boiling mercury. From the temperature of freezing mercury or thereabouts, to that of boiling water, they find the expansion of air to keep pace with that of mercury, as indicated by the common thermometer; but from the boiling point of water to that of mercury, the latter expands somewhat more in a proportion gradually increasing: as by the following Table.
TABLE I. +------------------------+-----------------+-----------------------+ | | | Temperature by an | | | | air Thermometer, | |Temperature by Mercurial| Corresponding | corrected for | |Thermometer. |volume of a given| expansion of glass. | | | mass of air. | | |Fahrenheit.| Centigrade.| | Centigrade. | +-----------+------------+-----------------+-----------------------+ | -33° | -36°| 0.8650 | -36.8 | | 32 | 0 | 1.0000 | 0 | | 212 | 100 | 1.3750 | 100 | | 302 | 150 | 1.5576 | 148.70 | | 392 | 200 | 1.7389 | 197.05 | | 482 | 250 | 1.9189 | 245.05 | | 572 | 300 | 2.0976 | 292.70 | | 680 |M. boil 360 | 2.3125 | 350.00 | +-----------+------------+-----------------+-----------------------+
The absolute dilatation of mercury claims their attention. They quote nine authorities for the expansion from freezing to boiling water temperatures; the extremes of these nine are, Casbois ¹/₆₇ of original volume, and mine ¹/₅₀ of the same. They determine it to be ¹/₅₅.₅. By doubling and tripling the elevation of the temperature, they made observations from which are deduced the results of the following Table. The dilatations are for each degree of the thermometer centigrade, to which I have added the corresponding ones for Fahrenheit’s.
TABLE II. +---------------------+-----------------+-------------------------+ | | Mean absolute | Temperatures indicated | |Temperature by an air| dilatations |by dilatation of mercury,| | Thermometer. | of mercury. | supposed uniform.[25] | +---------------------+-----------------+-------------------------+ | Fahr. Cent. | Fahr. Cent. | Fahr. Cent. | | 32° 0° | 0 0 | 32° 0° | | 212 100 | ¹/₉₉₉₀ ¹/₅₅₅₀ | 212 100 | | 392 200 | ¹/₉₉₄₅ ¹/₅₅₂₅ | 400.3 204.61 | | 572 300 | ¹/₉₅₄₀ ¹/₅₃₀₀ | 597.5 314.15 | +---------------------+-----------------+-------------------------+
[Footnote 25: That is, the temperature that would be denoted by mercury inclosed in a vessel having no expansion by heat; or else in one that expanded in the same rate as mercury.]
By a series of observations on the apparent dilatation of mercury in glass vessels, compared with the results in the above tables, they deduce the absolute dilatation of glass for each degree of the thermometer, and the temperature that would be indicated by supposing the uniform expansion of a glass rod adopted as the measure of temperature as under:
TABLE III. +---------------+--------------+-------------------+--------------+ | |Mean apparent | Absolute |Temperature by| |Temperature by |dilatation of | dilatation of |a Thermometer | |an air Thermom.| mercury | glass in |made of glass.| | | in glass. | volume. | | +---------------+--------------+-------------------+--------------+ | Fahr. Cent. | Fahr. Cent.| Fahr. Cent. | Fahr. Cent. | | 212° 100° |¹/₁₁₆₆₄ ¹/₆₄₃₀| ¹/₆₉₆₆₀ ¹/₃₈₇₀₀ | 212 100 | | 392 200 |¹/₁₁₄₃₀ ¹/₆₃₇₈| ¹/₆₅₃₄₀ ¹/₃₆₃₀₀ | 415.8 213.2 | | 572 300 |¹/₁₁₃₇₂ ¹/₆₃₁₈| ¹/₅₉₂₂₀ ¹/₃₂₀₀₀ | 667.2 352.9 | +---------------+--------------+-------------------+--------------+
The absolute dilatations of iron, copper, and platina were investigated with great address, from 0° to 100° and from 0° to 300° centigrade; and were found as per Table below, for each degree of the centigrade thermometer.
TABLE IV. +--------+---------------+--------+---------------+ |Temp. by|Mean dilatation|Temp. by|Mean dilatation| | the air| of iron, |iron rod| of copper | | Therm. | in volume. | Therm. | in volume. | +--------+---------------+--------+---------------| | Cent. | | | | | 100° | ¹/₂₈₂₀₀ | 100° | ¹/₁₉₄₀₀ | | 300 | ¹/₂₂₇₀₀ | 372.6 | ¹/₁₇₇₀₀ | +--------+---------------+--------+---------------+
+-----------+---------------+-----------+ | Temp. by |Mean dilatation| Temp. by | |copper rod | of platina |platina rod| | Therm. | in volume. | Therm. | +-----------+---------------+-----------+ | | | | | 100° | ¹/₃₇₇₀₀ | 100° | | 328.8 | ¹/₃₆₃₀₀ | 311.6 | +-----------+---------------+-----------+
Connected with this subject was another important enquiry, whether the capacities of bodies for heat remain constant at different temperatures, or whether they diminish or increase as the temperature advances. In other words, does a body that requires a certain quantity of heat to raise it from 0° to 100° centigrade, require the same quantity to raise it from 100° to 200°, and from 200 to 300°, &c.; or does it require less or more as we ascend? This enquiry involves that of the measure of temperature. They adopt the uniform expansion of air, or the air thermometer, as the proper measure, and find the capacity of iron,
From 0° to 100° = .1098 0 to 200 = .1150 0 to 300 = .1218 0 to 350 = .1255
the capacity of an equal weight of water being 1.
The following Table exhibits the capacities of seven other bodies according to their results.
TABLE V. +---------+--------------+--------------+ | |Mean capacity |Mean capacity | | | between 0° | between 0° | | | and 100° | and 300° | +---------+--------------+--------------+ |Mercury | .0330 | .0350 | |Zinc | .0927 | .1015 | |Antimony | .0507 | .0549 | |Silver | .0557 | .0611 | |Copper | .0949 | .1013 | |Platina | .0335 | .0355 | |Glass | .1770 | .1900 | +---------+--------------+--------------+
According to this table the capacities of bodies _increase_ with the temperature in a small degree: and the increase, though it would still exist, would be less, if the common mercurial thermometer were the measure of temperature.
Also supposing that thermometers made of these bodies and graduated by immersion in freezing and boiling water into 100°; if these were all immersed in a fluid in which an air thermometer stood at 300°. Then the relative temperatures of the several thermometers would be as under, if measured by the absolute quantity of heat acquired, namely,
Iron 322.2° Silver 329.3 Zinc 328.5 Antimony 324.8 Glass 322.1 Copper 320.0 Mercury 318.2 Platina 317.9
From these observations they infer that the law which has been promulgated for the refrigeration of bodies, cannot be strictly true: namely, that bodies part with heat in proportion as their temperature exceeds that of the surrounding medium.
Some animadversions on the general laws relative to the phenomena of heat, announced in my elements of Chemical Philosophy (page 13) then follow, together with a table drawn up to show the discordance between the air thermometer and the mercurial thermometer, both being graduated in the manner I proposed in the said elements. On these points I may have to remark in the sequel.
The first part of the Essay concludes with some remarks to shew why a preference should be given to the air thermometer, or more strictly, the thermometer whether of mercury or any other body, supposed to be graduated so as to correspond with an air thermometer of equal degrees.
The Second Part of the Essay is on
_The Laws of Refrigeration_.
Adopting the air thermometer as the most eligible measure of temperature, Messrs. Dulong and Petit proceed to investigate the laws of the refrigeration of bodies, under a great variety of circumstances, in _vacuo_ and in air or gases of different kinds and densities. The inquiry abounds with experiments and observations evincing great skill and acuteness; but which it will not suit our purpose to detail. It may suffice for us to give a general summary of the Laws deduced by them from their experiments, at the same time recommending all those who feel sufficient interest in the subject to peruse the essay at large, which exhibits a profound philosophical train of experiments, the results of which are illustrated by the aid of mathematical generalization.
“_Law 1._ If one could observe the cooling of a body placed in a vacuum, and surrounded by a vessel absolutely destitute of heat, or otherwise deprived of the power of radiating heat, the velocities of cooling would decrease in geometrical progression when the temperatures diminished in arithmetical progression.”
“_Law 2._ The temperature of a vessel containing a vacuum being constant, and a body being placed in it to cool, the velocities of cooling for excesses of temperature in arithmetical progression, decrease as the terms of a geometrical progression diminished by a constant number. The ratio of this progression is the same for the cooling of all kinds of bodies, and is equal to 1.0077.”
“_Law 3._ The velocity of cooling in a vacuum for the same excess of temperature, increases in geometrical progression, the temperature of the vessel circumscribing the vacuum increasing in an arithmetical progression. The ratio of the progression is the same as above, namely 1.0077 for all kinds of bodies.”
“_Law 4._ The velocity of cooling due to the sole contact of a gas is entirely independent of the nature of the surface of the cooling bodies.”
“_Law 5._ The velocity of cooling due to the sole contact of a gaseous fluid varies in a geometrical progression, while the excess of temperature itself varies in a geometrical progression. If the ratio of this second progression be 2, that of the first is 2.35, whatever be the nature of the gas and its elastic force.”
“This Law may be likewise announced by saying that the quantity of heat carried off by a gas is in all cases proportional to the excess of the temperature of the heated body raised to the power whose index is 1.233.”
“_Law 6._ The cooling power of a gaseous fluid diminishes in a geometrical progression, when its tension itself diminishes in a geometrical progression. If the ratio of this second progression is 2, the rate of the first is 1.366 for atmospheric air; 1.301 for hydrogen; 1.431 for carbonic acid; and 1.415 for olefiant gas.”