596 



and hydrochloric acid, the latter producing, with the monamine 

 liberated in the reaction, a salt which in its turn is likewise decom- 

 posed. 



Thus the chloride of diethylammonium, for instance, together with 

 chloride of ethyl and ethylamine, yields ethylene and chloride of 

 ethylammonium which splits into chloride of ethyl and ammonia. 



The idea naturally suggested itself, to attempt, by means of this 

 reaction, the formation of the primary and secondary monophosphines, 

 which are at present unknown. Experiments made with the view 

 of transforming triethylphosphine into diethylphosphine have as yet 

 remained unsuccessful, the chloride of triethylphosphonium distilling 

 without alteration. 



X. " Notes of Researches on the Polyammonias." No. IX. 

 Remarks on anomalous Vapour-densities. By A. W. HOF- 

 MANN, LL.D., F.R.S. Received July 24, 1860. 



In a note addressed to the Royal Society * at the commencement 

 of this year, I have shown that the molecules of the diamines, like 

 those of all other well- examined compounds, correspond to two 

 volumes of vapour f, and I have endeavoured to explain the apparent 

 anomalous vapour-densities of the hydrated diamines by assuming 

 that the vapour-volume experimentally obtained was a mixture of 

 the vapour of the anhydrous base and of the vapour of water. 

 Thus, hydrated ethylene-diamine was assumed to split under the 

 influence of heat into anhydrous ethylene-diamine (2 vols. of vapour) 

 and water (2 vols. of vapour). 



(C 2 H 4 )" 

 H 

 " 



The vapour-density of ethylene-diamine referred to hydrogen being 

 30, and that of water vapour 9, the vapour-density of a mixture of 



equal volumes of ethylene-diamine and water- vapour = - = 19*5, 



which closely agrees with the result of experiment. 



In continuing the study of the diamines, I have expanded these 



C 2 H 10 N 2 0= H 2 



* Proceedings, vol. x. p. 224. 



f H a = 2 vols. J H = l; = 16; C = 12, &c. 



