the Constitution of Carbon Compounds. 103 



of heat is developed as if combination were to take place 

 between an oxygen molecule and a single carbon atom, due 

 allowance being made for the change in volume. But it is 

 by no means certain that this is the case — that the addition 

 of the first and second atom of oxygen to a carbon atom 

 involves the development of the same amount of heat. The 

 argument that it does, which has been based on the results 

 obtained for certain solid oxides in cases where both higher 

 and lower oxide are ultimately obtained in the same state of 

 aggregation as the element oxidized, cannot, in my opinion, 

 be accepted in evidence, for the very reason that in the cases 

 in question solids are dealt with throughout. If we consider 

 what are the properties of carbon monoxide, they are such as on 

 the whole favour the contrary view, viz. that, of the total heat 

 developed in the formation of carbon dioxide, the larger pro- 

 portion is given out in the combination of the carbon atom 

 with a single oxygen atom. It is especially noteworthy, in 

 fact, that carbon monoxide does not appear to be so markedly 

 unsaturated, combining directly with but a limited number of 

 other bodies and, as a rule, only under special conditions. If 

 this view be accepted, 135340 units is too low a value for 

 /. d (§ 4) ; in other words, /. Ci = 135340 + a- ; and I think 

 facts justify the conclusion that x has a high value. 



(23) As the value /. Ci is made use of in deducing the 

 amount of heat developed in the formation of carbon com- 

 pounds generally, the calculation of the amount of heat 

 developed in the combination of hydrogen with carbon from 

 the heat of formation of methane and other hydrocarbons 

 must also be affected by the error which possibly has been 

 made in determining/. C^. 



(24) Thomsen's conclusion that v s = (§ 7) is also, I 

 imagine, evidence of a flaw somewhere in the argument by 

 which so improbable a conclusion is arrived at. Now, it is 

 assumed by him that the heat developed in the formation of 

 methane (59550 units) is given out in the combination of two 

 molecules of hydrogen with a single atom of carbon ; as pre- 

 viously explained (§ 6), it amounts in round numbers to 60000 

 units = 2 (2?'). The corrected value for the heat of formation of 

 methane will therefore be 60000 + x units, and the corrected 

 value of 2r will consequently be 30000 + \x units. But if 

 this be granted, it follows that, in order to determine v 3 , it is 

 necessary to add to the heat of formation of acetylene calcu- 

 lated by Thomsen (28990 units) twice the value of x, and to 

 deduct only 2r + £#=30000 + j&. This will give - 1010 + 1±#, 

 instead of zero, as the value of v 3 ; so that the heat of forma- 

 tion of acetylene may well be a fairly high positive value. 



