562 PEOF. LETTS AND ME E. F. BLAKE ON 



on a plate of unglazed porcelain, and placed in a desiccator to dry, but it became 

 so brown from separated iodine that it was not deemed advisable to analyse it. 

 It was decomposed with a hot solution of caustic potash, when an oily liquid resulted, 

 which was washed with water. Some of this, when exposed to the air and warmed, 

 gradually became crystalline, and the crystals when recrystallised from alcohol had 

 the appearance of oxide of tribenzyl phosphine. Another portion, when mixed with 

 crystallised iodide of benzyl, evolved heat, and the product when recrystallised from 

 alcohol separated in the characteristic form of tetrabenzyl phosphonium iodide, and had 

 the melting point 189° C. After these preliminary experiments, it was decided to 

 precipitate the remainder of the ethereal solution with hydriodic acid gas ; but as the 

 ethereal solution contained a little water, fractional precipitation was resorted to, as we 

 considered it probable that the first portions of the precipitated hydriodate would carry 

 down the whole of the water. This surmise was fully borne out by experiment, for 

 on passing hydriodic acid through the solution a quantity of a slimy white precipitate 

 separated, and on filtering from this and passing hydriodic acid through the filtrate, a 

 pure white flocculent precipitate was obtained, which was (after the solution had been 

 saturated) thoroughly washed with dry ether, and then dried in vacuo. On analysis, the 

 following numbers were obtained : — 



Analysis. 



(1) 1-0223 



required 26 c.c ^ 



AgN0 3 



= 03302 I = 32-29 per cent. 



(2) 0-5028 



12-3 c.c £ 



)> 



= 0156211 = 3106 





Found. 

 (1) 31-06 





Calculated for 



Iodine, 



(C 7 H 7 ) 2 HP.HI. (C 7 H 7 ) 3 P.HI 

 3713 29-39 



>> 



(2) 32-29 





... 



The above analyses indicated, in our opinion, that the compound was a mixture of 

 the hydriodates of dibenzyl phosphine and tribenzyl phosphine, a view of its composi- 

 tion which was rendered the more probable from the experiments described on p. 568 on 

 the action of iodide of benzyl on the primary phosphine, which were made almost at the 

 same time. We therefore decided to obtain a fresh and larger quantity of the 

 hydriodates. 



Experiment 3. — The contents of twelve sealed tubes were treated exactly as in 

 experiment 2, and an ethereal solution obtained of the " solidified oil." 



The bulk of this was treated with gaseous hydriodic acid, when a large quantity 

 of a white precipitate was formed. An attempt was made to saturate the solution 

 with hydriodic acid, but unfortunately the ether itself was rapidly attacked, yielding 

 water and iodide of ethyl, with the result that the hydriodates of the phosphines 

 were partly dissolved and a slimy mass obtained, which we could not dry nor do 

 anything with. 



Some of the ethereal solution of the cake of crude phosphines was mixed with a 

 filtered solution of sulphur in bisulphide of carbon, when much heat was evolved, and 



