520 Prof. R. Meldola on the Theory of the 



quinone, this compound being regarded by him as a double 

 ketone : — 







A 



HC CH 



II II 

 HC CH 



\c/ 



6 



Phenylene, according to this view, must be regarded as a 

 tetratomic radical, and a slight extension of the same view 

 enables us to consider phenyl as triatomic: — 



H 

 C= C— 



H(/ X CH HC^^CH 



II II II II 



HC CH HC CH 



If this assumption be made, it then becomes possible to 

 construct formulae for the mixed diazoamido-compounds which 

 meet all the requirements of the case, and which must, there- 

 fore, commend themselves to the notice of all chemists who, 

 like myself, have been puzzled to explain the behaviour of 

 these compounds in accordance with the existing theoretical 

 notions. The formula now proposed may be written in two 

 ways:- — 



N:N N.N. 



x/ > < ^ 



I. II. 



Of these two formulae I am disposed to attach the greater 

 weight to the first because it indicates the presence of the 

 very stable azo-group, — N : N — ; and this is in accordance 

 with the general character of the compounds, which decom- 

 pose under the influence of acids or of reducing agents in 

 such a manner that the N-atoms of the azo-group always 

 remain in combination, either in the form of a diazo-salt or a 

 hydrazine. On the other hand, the second formula indicates 

 the presence of the group =C=N . N=C=; and this might 



