62 



III. " Researches on the Arsenic-Bases." By A. W. HOF- 

 MANN, LL.D., F.R.S. Received November 24, 1860. 



In a previous note* I have shown the existence of a group of dia- 

 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 



* Proceedings of the Royal Society, " Researches on the Phosphorus-Bases. 

 No. IX. Phosphammonium Compounds," vol. x. p. 608. 



