lo Cain, The Constitution of the Ammonium Compounds. 



resembles both the older formula of Kekule and the 

 later one of Blomstrand in several important respects. 

 In Kekule's formula, 



C6H6.N = N.C1, 

 the double linking between the nitrogen atoms shows a 

 close analogy to the azo compounds, and the position of 

 the chlorine atom easily explains the formation of hydra- 

 zines thus, 



CeHsN = NCI + 4H -> CeHe . N - NH3CI. 



I 

 H 



The Blomstrand formula, on the other hand, 



CeHeN^N 

 I 



CI 

 shows the presence of pentad nitrogen, and is analogous 

 to the existing ammonium theory. It is difficult, how- 

 ever, to explain the reduction to hydrazine by this 

 formula, 



CsHbN^N + 4H 



CI 

 The new formula 



CeHsN - NH4 

 CI 



CeHsN - NH,C1. 



H 



CI X 



CeHeN^ I or Ar. N^. | 



'% 



N 



^ 



N 



explains the transition of a diazonium salt into a jrjw-diazo 



compound thus, 



Ar R Ar R 



N = N+ -»N = N 



\ / 

 X K X-K 



avoiding the change of linkage necessary according to 

 Hautzsch {loc. cit., p. 45), 



Ar R Ar R 



N = N+ I ->N = N 



X K X-K 



