474 Royal Society : — 



tomic bases, containing phosphorus and arsenic, which are formed by 

 the action of monarsines on the bromethylated bromide, so frequently 

 mentioned in my researches on the phosphorus-bases. The idea 

 naturally suggested itself to examine the deportment of this salt 

 under the influence of monostibines, with the view of producing the 

 phospho-stibonium-compounds. The two bodies react upon one an- 

 other, but only after protracted digestion or exposure to rather high 

 temperatures. The product of the reaction is complex, yielding a 

 comparatively small quantity of a difficultly soluble platinum-salt of 

 diatomic appearance. I have repeatedly modified the circumstances 

 and analysed the products in the form of platinum-salts ; I omit to 

 quote the detail of these experiments, since they have failed to dis- 

 entangle the difficulties of the reaction. 



Some experiments upon the deportment of dibromide of ethylene 

 with triethylarsine were more successful. The reaction between these 

 two bodies had been selected as a subject of inquiry by Mr. W. 

 Valentin, to whom I am indebted for valuable assistance at the 

 earlier stage of these researches. Circumstances have subsequently 

 prevented Mr. Valentin from carrying out his plan, and I have 

 therefore to take upon myself the responsibility for the following 

 statements. 



Action of Dibromide of Ethylene upon Triethylarsine. 



MONARSONIUM SERIES. 



The experience gathered during the examination of the phosphorus- 

 bodies, enabled me to establish the nature of this reaction by a com- 

 paratively small number of platinum-determinations. 



Bromide of Bromethyl-triethylarsonium. — To avoid as far as pos- 

 sible the formation of the second product, a mixture of triethylarsine 

 with a very large excess of dibromide of ethylene was digested in 

 sealed tubes at a temperature not exceeding 50° C. Notwithstanding 

 the low temperature, the tubes invariably contained compressed gases ; 

 the product of the reaction was treated with water, which extracted 

 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 As Br 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, 



* H = l; 0=16; S = 32; C = 12. 



