44 Mr. W. Sutherland on the Fundamental 



the C atom is dyad. In carbonic dioxide each junction C:0 

 is associated with the other junction C'rO ; and according to 

 what we have just seen this association ought probably to be 



characterized by an evolution of 15 kcal.; so that for /(CflO), 

 free from the effect of associated oxygen, we get the value 

 1 35*3/2 — 15 or 52*6 in harmony with the values found in 

 organic compounds ; and then comparing the values 67*6 



for/(C"0) in carbonic oxide, and 52*6 for/(CYO), we see the 

 passage from tetrad to dyad carbon is accompanied by an 

 evolution of 15 kcal. per gramme-atom. Now if in the bonds 

 phraseology we say that the conversion of tetrad to dyad 

 carbon is due to two bonds of the same atom satisfying one 

 another, then the heat of formation of dyad from tetrad 

 carbon would be/(OC), which in CO we have just found to 

 be 15, and which as one of the fundamental constants for 

 organic compounds we found to be 14, which is nearly the 

 same. Thus, then, the thermochemistry of the oxides of 

 carbon and of the alcohols, ethers, aldehydes, ketones, acids, 

 esters, and anhydrides canto a first approximation be brought 

 into consistency by the system of values f(G'G) = f(C :C) = 14*2, 

 /(CH) = 15, /(C-0-C) = 2/(C;0) = 37, /(C-0)+/(OH) = 44-5, 

 /\C:0)=53, with the provisos that the association of the 

 junctions C:0 and C*0, or C:0 and C:0, is accompanied 

 by the evolution of 15 kcal. for each C:0, and that the con- 

 version of tetrad into dyad carbon is accompanied by an 

 evolution of heat 15, or nearly /(OC). 



7. Nitrogen in Organic Compounds. — In treating of the 

 thermochemistry of nitrogen, Thomsen starts by seeking for 

 the thermal value of the bond uniting two If atoms. He 





 assumes that nitrogen dioxide has the constitution ~N\ | , and 



°\ /° ° 



nitric peroxide N — N [ ; so that the heat evolved when 



7 \) 



two molecules of N0 2 unite to form one of N 2 4 is the required 

 thermal value of a single binding between two nitrogen atoms. 

 Now from Berthelot's and Ogier's measurements of the specific 

 heat of gaseous N 2 4 , as with rising temperature it gets dis- 

 sociated into 2N0 3 (Ann. de Chim, et de Phys. 5th ser. xxx.), it 

 follows that the heat required for the complete dissociation is 

 13*25, while a theoretical estimate made by Boltzmann on 

 thermody mimical grounds gave the value 13*9. Thomsen 

 takes the mean 13' 6, and subtracting '6 for the doubling of 

 the volume, gets 13 as the heat of complete dissociation of 

 N 2 4 at constant volume, and this, then, he takes as the 

 thermal value of a single binding of two IS atoms, 



