854 



SIR B. C. BBODIE ON THE CALCULUS OF CHEMICAL OPERATIONS. 



Tlie second column contains the symbol, as expressed by the factors u, x, i, • • ■ ■ I the 

 third column the temperatures at which the observation is made ; column A, the density 

 of the substance, the density of air being assumed as 1; column B, the same density, 

 the density of hydrogen being 1 ; column C contains the density as calculated from the 

 symbols given in the first column. 



It will be seen on inspection of the preceding Table that, in many instances, the 

 vapour-density, as determined by experiment, does not sufficiently agree with any hypo- 

 thesis even remotely probable. 



Many of these apparent exceptions obviously admit of a similar simple explanation 

 to that which has been suggested in the case of chloride of ammonium. Indeed, it 

 would be truly surprising if in the varied transformations of matter no example of such 

 decomposition should occur. In more than one case actual evidence of it has been 

 adduced * ; and while undoubtedly it must be allowed that the question is not to be 

 answered by theoretical considerations alone, but that every case of such apparent 

 anomaly should be submitted to the most rigid tests of experiment, there is every reason 

 to believe that the simple weights a,, ^, 0, ^, . . . . are the ultimate known components 

 of the units of ponderable matter, and represent a limit to chemical decomposition 

 which has not as yet been passed. 



* See PtATFAiR and "Wankltn, Joum. Chemical Society, vol. xv. p. 142 ; "WANKira and Eobixson, " On 

 Diffusion of Vapours," Proceedings, Royal Society, vol. xii. p. 507. 



