68 Royal Society : — 



Formula of Dr. Ilofmann. 



(C.H,)" 

 Ethylene-diamine .... C 4 H 8 N 2 = H 2 [► N a . 



(C H V 

 Diethylene-diamine .. C 8 H 10 N a =(C 4 H 4 )'' j- 



(C H V 

 Triethylene-diamine . . C 12 H 12 N 2 = (C 4 H*)" }> N 2 . 



(C 4 H 4 )" 



It was by careful examination of the physical properties of the 

 bases under consideration, and more especially by the absence of 

 simple equations capable of explaining the formation of the first and 

 of the thirdjterms of the series, that I had first been led to doubt the 

 correctness of M. Cloez' s formulae ; but I would not have expressed 

 this doubt, if, on repeating the analysis of the first base, of formen- 

 amine, the slightest doubt on the subject had remained in my mind. 

 I did not at the time investigate the two other bases, and I limited 

 myself to stating that the constitution of these bodies would probably 

 be found analogous to that which I had experimentally established 

 for the first term of the series. 



Let us now examine the objections which M. Cloez has brought 

 forward against my argument. "According to the hypothesis of 

 M. Hofmann," says he, " the action of ammonia on the chlorinated 

 and brominated hydrocarbons cannot give rise to the formation of 

 chloride or bromide of ammonium ; the reaction consists simply in a 

 combination of the two substances, without the separation of a third 

 compound : it is a case of sytnmorphosis or addition, 



(C 4 H 4 ) C1 2 + 2H 3 N=(C 4 H 4 )H 4 N 2 , 2HC1. 

 Experiment proves, however, that the reaction involves the elimi- 

 nation of hydrochloric acid and the fixation of the elements of 

 amidogen : apomorphosis and symmorphosis are accomplished side 

 by side, as indicated by the following equation: — 



C 4 H 4 C1 2 + 2H 3 N=(C 4 H 3 )H 2 N, HC1 + H 3 N, HC1." 



M. Cloez would be perfectly right if during the reaction no other 

 base were formed except the first one. But he forgets altogether 

 that in the process under examination — exactly as in the mutual 

 reaction between bromide of ethyle and ammonia — several other bases 

 of more advanced substitution are produced. The equations which 

 I give for the formation of these bodies likewise involve the elimi- 

 nation of bromide of ammonium, and in fact of considerable quantities 

 of this compound. 



2(C 4 H 4 )" Br 2 + 4H 3 N=(C 4 H 4 ) 2 " H 2 N 2 , 2HBr+2(H 3 N, HBr). 

 3(C 4 H 4 )" Br 2 + 6H 3 N=(C 4 H 4 ) 3 " N 2 , 2 HBr+4 (H 3 N, HBr). 

 The bromide of ammonium then, which separates in considerable 

 quantity in the action of dibromide of ethylene upon ammonia, be- 

 longs to the second and third portions of the reaction ; it has nothing 

 whatever to do with the formation of the first base. M. Cloez, as I 



