NEW LAW IN THERMOCHEMISTRY 



13 



So far the agreement with theory is remarkable, but there are 

 three exceptions to be noted. The formulae relate to the prod- 

 ucts of the reactions. 



Crotonic aldehyde, 

 Mesityl oxide, 

 Cinnamic alcohol. 



C.HgOBr, 

 CeH,oOBr, 

 CjHioOBr, 



19349 

 20238 

 22321 



Whatever these exceptions may mean, it is clear that the rule 

 holds in nine cases out of twelve, giving an average value for 

 the henotherm of one half of 27 530, or 13 765, and this agrees 

 with the values so far derived from other sources. 



In order to test our general formula still farther, let us apply 

 it to the organic compounds of nitrogen. Beginning with the 

 amines, for which Thomsen gives adequate data, we have equa- 

 tions of this type, in which -w represents the heat of formation of 

 the molecule of nitrogen. For ethylamine, CgHg.HgN the quad- 

 rupled formula is C^HjgN^, giving 



8a" -I- 14JK -(- 27t/ — \<^z — 4/'= I 516758 calories, 



when all the substances are gaseous. The derived formula is 

 exactly the same as that for the hydrocarbons, except that a 

 factor for nitrogen must be introduced, and this when m repre- 

 sents the number of nitrogen molecules produced, is 9 in. The 

 formula thus becomes 



4^ 



\2a -\- 6h ■\- <^m — c — 8n 



= constant. 



and from this we find that nine henotherms, or 123 300 calories, 

 is the heat of formation of Nj. This very high value corre- 

 sponds well with the known stability and inertness of nitrogen. 

 The table for ten aliphatic amines, with the constant yielded by 

 the formula, is as follows : 



