290 ORGANIC CHEMISTRY 



law. In a similar manner, if we accept the theory of the sequence of 

 atoms in carbon compounds, there seems no reasonable possibility 

 other than that van't Hoff's hypothesis is true in its broad out- 

 lines. 



I hope I may be pardoned here for a brief digression. I am aware 

 that Franz Wald 1 believes that he can give a satisfactory explanation 

 of the laws of fixed and multiple proportion and of combining weights 

 without the aid of the atomic theory, and that Professor Ostwald in 

 his recent Faraday lecture 2 has accepted and expanded the same 

 thought. I will say frankly that their reasoning does not appear to 

 me conclusive. Ostwald defines a chemical individual as "a body 

 which can form hylotropic phases within a finite range of tempera- 

 ture and pressure," 3 and deduces from this the fact that a given 

 hylotropic phase must have a fixed composition. He appears to forget 

 that the existence of these hylotropic phases implies that the pro- 

 perties of matter are discontinuous, or, in other words, that there is 

 a finite number of hylotropic bodies, one of the facts for which the 

 atomic theory gives an explanation. 



There is another characteristic, too, of a chemical compound which 

 all chemists will agree is at least as important as that it shall consist 

 of a "hylotropic phase. " This is that the compound must not only 

 have a fixed composition, but this composition must bear a definite 

 relation to those numerical quantities which represent the proportion 

 in which each element of which it is composed always combines 

 with other elements. I need hardly add that these numerical quan- 

 tities are so deeply seated in the properties of matter that, having 

 adopted a unit, all chemists are absolutely agreed in selecting one 

 and only one such quantity for each of the well-known elements. 



In attempting to deduce this law of combining weights Ostwald 

 assumes that three elements form the compounds AB, AC, BC, and 

 ABC, and adds, "There shall be but one compound of every [each] 

 kind." With this assumption, his reasoning may be sound, but I 

 fail to see how it applies when we find ten thousand compounds 

 ABC instead of one. The case which he supposes is so far theoretical 

 that I have been unable to find an actual case where the compound 

 ABC can be formed, by the union both of AB with C and of AC with 

 B. 4 But I have taken too much time with a matter which is aside 



1 Ztschr. Phys. Chem., 24, 633, 1897. 



2 J. Chem. Soc. (London), 35, 506. 



3 Ibid., p. 515. 



4 It is quite possible that such an illustration may be found, but, in any case, 

 Professor Ostwald's deduction cannot be made to apply to those cases in which 

 the compound ABC does not exist, nor to those cases where the compound ABC 

 cannot, even theoretically, be supposed to consist in turn of a known compound 

 AB combined with C and of another known compound AC combined with B. 

 Such cases are common because of the fact of valence. In its simplest form the 

 law of combining weights is quite independent of the existence of the compound 

 ABC and may be stated thus: If the composition of two compounds A B and BC 



