394 Royal Society : — 



more connected form, I hope soon to lay before the Royal Society, 

 I have not, indeed, met with the whole of these compounds ; but in 

 the place of the deficient members of the groups new products have 

 made their appearance, whose formation in the present state of our 

 knowledge could scarcely have been predicted, and thus the problem 

 of disentangling the difficulties of this reaction becomes a task of 

 very considerable difficulty. Nor did the action of dibromide of 

 ethylene upon ethylamine, diethylamine, and triethylamine, which I 

 subsequently studied, afford a sufficiently simple expression of the 

 transformations suggested by theory. The difficulties disappeared at 

 once when the experiment was repeated in the phosphorus-series. In 

 the reaction with dibromide of ethylene, the sharply-defined characters 

 of triethylphosphine exhibited themselves with welcome distinctness, 

 and in consequence more especially of the absence of unreplaced 

 hydrogen — whereby the formation of a large number of compounds 

 of subordinate theoretical interest was excluded — the general cha- 

 racter of the reaction, the recognition of which was the object cf 

 the inquiry, became at once perceptible. 



I have shown that the action of dibromide of ethylene upon 

 triethylphosphine gives rise to the formation of four different com- 

 pounds, viz. 



[(C 2 H 4 )" (C 2 H 5 ) 6 P 2 ]"Br 2 



[(C 2 H 4 Br)(C 2 H 5 ) 3 P] Br 



[(C,H 8 0)(C,H 8 ),P] Br 



[(C 2 H 3 ) (C 2 H 5 ) 3 P] Br, 



each of which represents one of the four groups of compounds, 

 which under favourable circumstances may arise from the mutual 

 reaction between ammonia and dibromide of ethylene, the produc- 

 tion of a greater number of terms being impossible on account of 

 the ternary substitution of triethylphosphine. 



Whilst going on with the researches on the phosphorus-bases 

 which I have taken the liberty of submitting to the Royal Society, 

 in notes sketched as I advanced, 1 have not altogether lost sight of 

 the experiments in the nitrogen-series, which had originally sug- 

 gested these inquiries. Numerous nitrogenated bases, both mono- 

 atomic and diatomic, with which I have become acquainted during 

 this investigation, must be reserved for a future communication. I 

 may here only remark, that these substances, although differing in 

 several points, nevertheless imitate in their general deportment so 

 closely the corresponding terms of the phosphorus-series, that the 

 picture which I have endeavoured to delineate of the phosphorus- 

 compounds, illustrates in a great measure the history of the nitrogen- 

 bodies. 



In conclusion, a few words about the further development of 

 which the experiments on the polyatomic bases appear to be capable, 

 and about the direction in which I propose to pursue the track which 

 they have opened. 



Conceived in its simplest form, the transition from the series of 



