Dr. Hofmann on the Arsenic-Bases. 4<75 



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 6 ) 3 As] CL Pt Cl a . 



Compounds of Finyl-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 filtrate 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 

 oxide of silver, yields a powerfully alkaline solution, the nature of 

 which was determined by the analysis of the corresponding platinum- 

 salt. Transformed into the chloride and precipitated with dichloride 

 of platinum, this solution yielded beautiful rather soluble octahedra 

 which were found to contain 



8 H 18 A S PtCl 3 =[(C 2 H 3 ) (C 2 H 5 ) 3 As] CI, PtCl 2 . 



The analysis of this salt shows that the transformation of the brom- 

 ethylated compound ensues according to the following equation, 



[(C 2 H 4 Br) (C 2 HJ 3 As]Br+^j} O^ * 1 ^ ( C ^^ } O-f 2AgBr. 



The idea suggested, itself that the vinyl-compound obtained in this 

 reaction might be a secondary product resulting from the decom- 

 position of an oxethylated compound of limited stability formed in 

 the first instance, 



[(C 2 H 5 0) (C 2 H 5 ) 3 As] | 0= H | 0+ [(C 2 H 3 ) (C 3 H 6 ) 3 As] j Q 



It was with the view of avoiding this decomposition that in one of 

 the operations the digestion was accomplished at the common tem- 

 perature ; the result, however, showed that even in this case the 

 vinyl-compound was obtained. 



Nevertheless the oxethylated body appears to exist : under cir- 

 cumstances which were not sufficiently well observed at the time, the 

 action of oxide of silver upon bromide of bromethylated triethyl- 

 arsonium yielded an octahedral platinum -salt, which on analysis fur- 

 nished exactly the platinum-percentage of the oxethylated compound. 

 2 12 



