NEW LAW IN THERMOCHEMISTRY II 



ries. By comparing this with the directly measured affm-cnt 

 heat of combustion of amorphous carbon, 96 960 calories, he 

 deduces that the difference between the two quantities, 38 380 

 calories, represents the heat absorbed in gasifying and dissoci- 

 ating the solid elementary molecule. If, however, the absolute 

 heat of formation of carbon dioxide is assigned the higher value 

 as shown above, then the corresponding difference between it 

 and the ordinary or apparent heat is 67 440 calories, or very 

 nearly five henotherms. From this we must deduct the heat 

 expended in the dissociation of one oxygen molecule, or 13 700 

 calories, leaving 53 740 as due to the volatilization and isolation 

 of one carbon atom. Four henotherms equal 54 800 calories 

 approximately, a quantity which seems more probable than the 

 surprisingly small estimate made by Thomsen. 



Again, the absolute heat of formation which I have assigned 

 to the iodine molecule is practically double the value calculated 

 by Boltzmann^ from the dissociation phenomena of the element. 

 The reasons for these and other similar differences I shall not 

 attempt to trace ; but additional evidence will in due time be 

 presented in favor of the new values. 



We have already seen that the magnitude of n in the general 

 formula is equal to two henotherms, or about 27 400 calories, for 

 each atomic linking. I must also reiterate that every such link- 

 ing counts for one only, regardless of double or triple bonds. 

 In other words — the absolute heat of forrnation of an aliphatic 

 hydrocarbon, or of its halogen derivative, is proportional to the 

 fiumber of atomic unions in the molecule, and seems to bear no 

 relation to the masses of the atoms combined. Hydrocarbons, 

 chlorides, bromides and iodides all follow the same rule ; and 

 in it we have a first glimpse of something like a true general 

 law. By applying the values already given to CO,, H,0, 0„ 

 CI2, Br2 and Ig to the evaluation of r in the fundamental equations 

 of combustion, we can test this principle, and see how far the 

 facts support the theory. Thus, in all of the following com- 

 pounds n = 4, and hence, in each case, the absolute heat of for- 

 mation should be 4 X 27 400, or 109600 calories. By evaluating 

 r in the equations we get the following results. 



2 Wiedemann's Annalen (2), 22, 71. 



