419 



They may be recrystalllzed from water ; only on protracted ebullition 

 they are decomposed with separation of metallic gold. 



The triatomic ammonias, the history of which I have endeavoured 

 to trace in this paper, are naturally connected with the triatomic 

 alcohol discovered by Wurtz, and described by him under the name 

 of diethylene-alcohol. Diethylene-triamine and triethylene-triamiue 

 occupy in the series of diethylene-alcohol the position which is held 

 by ethylamine and diethylamine, by ethylene-diamine and diethyleue- 

 diamine in the series of ethylic and ethylenic alcohols respectively, 



Ethyl-alcohol. Ethylene-alcohol. Diethylene-alcohol. 



(C 2 H 5 )] (C 2 H 4 )") (C 2 H 4 )"En 



H IN H 2 K (C 2 H 4 )HK 



H J - H 2 j H 3 J 



Ethylamine. Ethylene-diamine. Diethylene-triamine. 



(C 2 H 4 )yN 3 



H 2 



Diethylamine. Diethylene-diaraine. Triethylene-triamine. 



The above formulae disclose the perfect symmetry which obtains 

 in the construction of the diatomic and triatomic ammonias ; they 

 also show the number and diversity of the ammonias of increasing 

 atomicity. 



If the substitution be carried to the furthest limit, viz. to the com- 

 plete replacement of the hydrogen in the type ammonium, ethylenic 

 substitution in the diatomic derivatives produces four compounds, in 

 the same manner as ethylic substitution in ammonium itself. The 

 group of triatomic ethylene-ammoniums does not comprise less than 

 jive compounds, the last term of the series being a non- volatile body 

 containing six molecules of ethylene and represented by the formula 



the existence of which is sure to be established experimentally by the 

 continuation of these researches. 



