158 Royal Society : — 



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. 



" Notes of Researches on the Poly- Ammonias." — No. IX. Remarks 

 on anomalous Vapour-densities. By A. W. Ilofmann, 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 hy 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). 



h: 



C 2 H 10 N 2 O= H, 2 K+li} *- 



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 = — X_= 19*5, 



which closely agrees with the result of experiment. 



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

 experiments. Without going into the detail of the inquiry, I beg 

 leave to record an observation which appears to furnish an experi- 

 mental solution to the question. 



Ethylene-diamine, when submitted to the action of iodide of ethyle, 

 yields a series of ethylated derivatives, amongst which the diethylated 

 compound has claimed my particular attention. This body in the 

 anhydrous state is an oily liquid containing 



C G H 10 N 2 =(C 2 H 6 ) 3 lN a . 

 H 2 J 



"With water it forms a beautiful crystalline very stable hydrate §, of 

 the composition 



c 13 N 2 = (C 2 IL) 2 [N 2 -f;J[0. 



Hj 



* Phil. Mag. vol. xx. p. 66. 



t H 2 = 2 vols. \ H=l; = 16 ; C = 12, &c. 



§ Phil. Mag. vol. xix. p. 232. 



