191 



of the oxide of silver has profoundly changed the original system of 

 molecules. Hydriodic acid no longer produces the salt difficultly 

 soluble in alcohol ; by evaporating the solution a crystalline residue 

 is obtained, which easily separates into a viscous, extremely soluble 

 substance, and splendid crystals of an iodide, very soluble in water 

 and alcohol, but insoluble in ether. The analysis of this iodide has 

 proved it to contain 



CHPI 



U18 



I. 



This formula represents the iodide of methyl-triethylphosphonium, 

 which was formerly obtained by M. Cahours and myself, by acting 

 with iodide of methyl upon triethylphosphine. 



The alkaline liquid, obtained by the action of oxide of silver upon 

 the tri-iodide, when saturated with hydrochloric acid, yields no longer 

 the platinum salt, difficultly soluble in water but soluble in hydro- 

 chloric acid. In a dilute solution no precipitate whatever takes 

 place, and only after considerable evaporation well-defined deep 

 orange-yellow octahedrons are deposited, which contain 



C U H 18 PC1, PtCl 2 = 



Cl, PtCl a . 



From these results it is obvious that the triphosphonium-salt, 

 when submitted to the action of oxide of silver, passes over into a 

 monophosphonium-compound. The latter is not the sole product of 

 the reaction ; I have already alluded to the viscous deliquescent 

 substance which accompanies the iodide of methyl-triethylphospho- 

 nium. This is an iodide, which, in the solution produced by the 

 action of oxide of silver upon the original tri-iodide, exists in the form 

 of oxide. The latter substance is easily recognized by evaporating 

 the solution of oxide of methyl-triethylphosphonium, and adding a 

 concentrated solution of potassa, when the oily globules characteristic 

 of the dioxide of triethylphosphonium separate, which disappear 

 immediately on addition of water. 



The metamorphosis of the tri-iodide, under the influence of oxide 

 of silver, is represented by the following equation : 



