50 Mr. W. Sutherland on the Fundamental 



10. Nitro- Compounds. — The values of p + ad for nitro- 

 methane and nitroethane are 55*8 and 101*9, from which 

 Thomsen subtracts 3 r and 5 r + **i respectively, having as 

 mean remainder 11*8 for the heat of forming the group N0 2 , 

 and attaching it to a carbon atom in the CH 3 or C 2 H 5 , but for 

 the junction of C and N by a single bond Thomsen takes his 

 former value 2*6, so that 9*2 remains for the heat of formation 

 of N0 2 , but according to experiment this heat of formation 

 is really — 8*4 ; and Thomsen concludes from this discrepancy 

 that the nitroparaffins cannot contain the group N0 2 , pro- 

 ceeding to show that according to his thermochemical con- 

 stants the nitroparaffins must be regarded as paraffins in which 

 two atoms of H are replaced by the two groups NO and OH. 



But we shall see immediately that there is no necessity to 

 assign this improbable constitution to the nitroparaffins, for, 



accepting the orthodox constitution such as H 3 C— N__qj we 

 have in our notation the equation 



/(ON)+2/(N:0) = ll-8; . . . .(52) 



but in our study of the oxides we gathered that /(N:0) is 

 small and might be taken as zero, and in the amines /(C'N) 

 was seen to be probably small, say zero : thus equation (52) 

 discloses a secondary effect which will be discussed in con- 

 nexion with another to which we proceed. 



For the nitrites of ethyl, isobutyl, and anryl, Thomsen gives 

 the following values of p + ad y namely, 105*6, 1 98*4, and 236*6 ; 

 but for the formation of ethyl, isobutyl, and amyl we have the 

 expressions br + v^ 9r + 3v h and llr + 4:Vi, whose values are 

 89*2, 177*6, and 221*8 : so that for the formation of the 

 — 0— N=0 and its attachment to the free carbon bond of 

 the alkyl radicals we have the values 16*4, 20*8, and 14*8, 

 of which the mean is 17*3, whence the equation 



./(C*0)+/(N*0)+/(N:0) = 17*3, . . (53) 



/. /(C*0) = 17*3, (54) 



a result in harmony with the values 18*5 and 15 formerly 

 found, see (33). 



Now for ethyl nitrate the value of p + ad is 115*5 ; sub- 

 tracting 89*2 for ethyl, we get for the formation of —O — N 2%* 



and its attachment to ethyl the value 26*3, whence the 

 equation 



/(C*Oj+/(N'0) + 2/(N:0) = 26-3, . . (55) 



