TRANSACTIONS OF SECTION B. 637 



9. Integral Weights in Chemistry. 

 By T. Sterrt Hunt, LL.D., F.R.S. 



The author began by insisting that changes of state, such as the condensation 

 of vapours to liquids and solids, the vaporisation of these, the fusion of solids, and 

 also the transformations alike of gaseous (liquid and solid) species, whether ele- 

 mental or compound, are comprehended under the general head of chemical meta- 

 moi-phosis. He considered the relations of all these changes to temperature and 

 pressure, and noted that while passing alterations in volume alike in solids, liquids, 

 and gases are not chemical but dynamical, the phenomenon of elasticity in gases 

 and vapour is a manifestation of chemical change, giving rise to new species which 

 are unstable at the existing temperature. He next remarked the diiference between 

 metamorphosis, or homogeneous change, and metagenesis, or heterogeneous change, 

 in both cases including alike integration and disintegration. He insisted upon the 

 subordination of all chemical changes to simple relations of measure, number, and 

 weight, as appears from the facts of definite and multiple proportions and from 

 progressive series. 



Regarding the chemical species as an integer, and rejecting the language of 

 the atomic or molecular hypothesis, the author designates the equivalent or so-called 

 molecular weight as the integral weight of the species. This weight for gases and 

 vapour is calculated from tliat of hydrogen gas as the unit of weight, the specific 

 gravity of such bodies varying directly as their integral weights. It is farther 

 maintained that the law of volumes governs equally the combination of gases and 

 vapours, and their condensation into liquid and solid integers. These have conse- 

 quently very high integral ■v^eights, which may be calculated like those of gaseous 

 species by comparing their specific gravities with that of hydrogen gas — which is 

 the true and natural unit of specific gravity for all species alike — or else with that 

 of water, which is generally assumed as the unit of specific gravity for liquid and 

 solid species. "Water is generated by the integration of 1,628 volumes of water 

 vapour at 100° and 7G0 mm. into one volume of the same temperature. Direct 

 determination of the weights of equal volumes of steam and water shows that the 

 integral weight of the former is not 180, but very nearly 17"963.3 — corresponding 

 to the corrected number for oxvgen — so that the integral weight of water, 

 1628 (H.0) = 29244; that of steam H20 = 17-9633, and that of hydrogen 

 gas H, = 2. 



The question of the contraction of water from 100° to 15° and 4°, the points 

 generally assumed for the unit of specific gravity, was next considered, and also the 

 fact that the density of all liquid and solid species should theoretically be taken at the 

 highest temperature which they can sustain without chemical change. But in view 

 of the errors incident to the determination of such densities in solids, and their 

 relatively small coefficients of expansion, it is believed that those taken at ordinary 

 temperatures give us sufficiently near approximations. 



The high integral weights thus fixed for liquids and solids in which the unit of 

 specific gravity for gases is multiplied by 29244 are in accordance with the notion 

 of great condensation, or so-called polymerisation in such species, which has been 

 maintained by many chemists, and notably by the author since 1853. It now 

 becomes possible, by fixing their integral weights, to give their true formulas for all 

 species, and to show that even the salts of the ammoni-cobalt bases, and those of 

 the so-called 'complex inorganic acids' of Wolcott Gibbs have higher integral 

 weights than was before suspected. The relations of the process of condensation 

 or integration to hardness and to chemical indifference were noticed in conclusion, 

 and allusion was made to the more detailed discussion of this subject in the author's 

 lately published volume, entitled, ' A New Ba'=is for Chemistry,' and in a more 

 recent essay on Chemical Integration, in both of which it is maintained that these 

 are, like specific gravity itself, functions of the integral weight.' 



Published in exienso in the Phil. Mag. for Oct. 1837. 



