98 Prof. H. E. Armstrong on the Determination of 



Table X. 



Components. 



Product. 



P". 



P"-(P+P'). | 



Methylamine P'= 8380 



Methane P =21170 



Dimethylamine ... P'= 10980 



Ethylamine F= 15770 



Ethane P =27400 



Diethylamine P' = 26420 



1 Dimethylamine . . . 

 L Trimethylamine . . . 



L Diethylamine ..... 

 1 Triethylamine 



10980 

 13550 



26420 



38020 



-18570 

 -18600 



-16750 

 -15800 



one by hydrocarbon radicals, on which view it is to be ex- 

 pected that equal amounts of heat would be developed 

 at each stage. This, however, is not the case (Table X.) : 

 the displacement of the first hydrogen atom by methyl 

 occasioning a much smaller heat-disturbance than that of 

 either the second or third atom, the amounts being very 

 nearly the same in the case of these latter however. The 

 difference may arise either because the hydrogen atoms in 

 ammonia are of different value, or because the change is 

 not of the nature supposed. In the former case one of the 

 hydrogen atoms must be regarded as more firmly held than 

 the other two, and in the formation of methylamine that which 

 is most firmly held would be first displaced ; but it is not 

 easy to explain why this should be the case. Moreover, in 

 the formation of the group C . NH 2 , on the one hand in the 

 primary amines containing methyl, ethyl, propyl and amyl, on 

 the other in aniline and allylamine, there is a difference in the 

 amounts of heat evolved of about 7000 units. It is also im- 

 probable, if the constitution of the amines be that commonly 

 supposed, that the introduction of the first methyl or ethyl 

 into ammonia should involve an increase in the heat of neu- 

 tralization, and that of the second and third a considerable 

 diminution*. Thomsen therefore seeks to deduce the heat of 

 formation of the primary amines of the first group on the 

 assumption that they differ in constitution from those of the 

 second group. Assuming the nitrogen to be pentadic, the 

 constitution of methylamine may be represented by the for- 

 mula H 2 C : NH 3 , i, e. it may be regarded as formed by direct 

 combination of methylene with ammonia. The heat of for- 



* 4 m ™ nia J2270 ) Uni f h deve i oped on 



Methylamine . 13115 / neutralizing with » chlox _ 



8740 ) h ? dric acid ' 



Dimethylamine 

 Trimethylamine , 



