63 



a soluble bromide from the ethylene-compound unacted upon. On eva- 

 poration, a beautiful bromide was left, which being copiously soluble 

 in boiling, and sparingly soluble in cold alcohol, could be readily re- 

 crystallized from absolute, and even from common alcohol. In water 

 this substance is excessively soluble, and therefore scarcely crystal- 

 lizable from an aqueous solution. 



Analysis, as might have been expected, proved this salt to be the 

 analogue of the bromethylated triethylphosphonium-salt. It contains 

 C 8 H 19 AsBr 2 =[(C 2 H 4 Br) (C 2 H 5 ) 3 As] Br*. 



The bromide of bromethyl-triethylarsonium, the composition of 

 which is sufficiently established by the analysis of the corresponding 

 platinum -salt, can be obtained in beautiful crystals. Their form was 

 determined by Quintino Sella ; it corresponds exactly with that of 

 the corresponding phosphorus-compound. 



Platinum-salt. The solution of the previous salt, converted by 

 treatment with chloride of silver into the corresponding chloride, 

 yields with dichloride of platinum, splendid needles of a double salt, 

 difficultly soluble in cold and even in boiling water, which contain 

 C 8 H 19 Br As Pt C1 3 = [(C 2 H 4 Br) (C 2 H 5 ) 3 As] Cl, Pt Cl a . 



Compounds of Vinyl-triethylarsonium. 



The bromide of bromethyl-triethylarsonium, like the corresponding 

 phosphorus-compound, loses its latent bromine under the influence 

 of oxide of silver. If the solution of the bromide be precipitated 

 by an excess of nitrate of silver, one half of the bromine separates as 

 bromide of silver ; the clear nitrate mixed with ammonia yields the 

 second half of the bromine in the form of a dense precipitate. 

 Nevertheless the reaction differs from that observed in the phos- 

 phorus- series. The bromide of the bromethylated phosphonium, as 

 has been pointed out in a former part of the researches on the phos- 

 phorus-bases, is almost invariably converted into an oxethylated body, 

 its transformation into a vinyl-compound being altogether exceptional. 

 The bromide of the bromethylated arsonium, on the other hand, yields 

 as a rule the vinyl-body of the series, the formation of an oxethylated 

 compound taking place only under particular circumstances, in fact 

 so rarely as to leave some doubt regarding the existence of this term 

 of the series. 



The bromide of bromethylated arsonium, treated with an excess of 



* H = l; = 16; S = 32; C = 12. 



