621 



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 of 

 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 6 ) 3 P] Br 



[(C 2 H 5 0)(C 2 H 5 ) 3 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, I 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 



2 u2 



