652 



which I endeavoured to grasp is most abundantly produced when 

 the triethylphosphine is rather in excess. Indeed, it would appear, 

 that under those conditions, the bromide in question constitutes the 

 principal product of the reaction. 



Not more successful was an attempt to increase the chances of 

 separation by reducing the number of the bromides. 



As I have previously stated, treatment with oxide of silver de- 

 stroys the triethylated-bromethylene-phosphonium, converting it into 

 a basic compound, which contains no longer any bromine, ^whilst 

 the same agent transforms the bromide of triethylphosphonium into 

 the oxide of argento-triethylphosphonium, and the dioxide of tri- 

 ethylphosphine. On saturating again by hydrobromic acid the liquid 

 thus produced, the solution now contained only the new bromide, the 

 bromide of the debrominetted body, and the dibromide of triethyl- 

 phosphine, the extreme solubility of which rendered its presence al- 

 most harmless. The task was thus virtually reduced to the separation 

 of two bromides. Unfortunately, the two substances resemble each 

 other to such an extent, that this hope also had to be abandoned. 



A modification, however, of this process led to the solution of the 

 difficulty. On saturating the alkaline solution, produced by the action 

 of oxide of silver upon the crude bromides, with hydriodic instead of 

 hydrobromic acid, a mixture of the corresponding iodides was ob- 

 tained, the separation of which could be easily accomplished. 



On moderately concentrating this solution, a beautiful iodide of 

 limited solubility was deposited. This substance readily dissolved in 

 boiling water, from which it crystallized on cooling in long white 

 needles. It was less soluble in alcohol, insoluble in ether. 



The analysis of this compound, carefully purified by repeated 

 crystallizations, led to the following atomic expression : 



C U H,,PI. 



This formula received ample confirmation by the examination of 

 a platinum- and gold-compound. Converted into chloride and pre- 

 cipitated by dichloride of platinum, the new body furnished a crystal- 

 line, difficultly-soluble platinum-salt, differing from the platinum-salts 

 of all the other compounds of this group. This salt dissolves in 

 boiling concentrated hydrochloric acid without decomposition, and 

 crystallizes on cooling in beautiful yellow needles containing 



