568 PROF. LETTS AND MR R. F. BLAKE ON 



its selenium compound. To produce this substance some of the ethereal solution, obtained 



as we have described above, was mixed with bisulphide of carbon and freshly precipitated 



selenium. The selenium rapidly disappeared, and a white precipitate was formed. This 



was boiled with alcohol, in which it was insoluble, then dissolved in a large quantity of 



boiling glacial acetic acid, the solution filtered from excess of selenium, and allowed to 



cool, when beautiful silky needles separated, which were colourless. They melted at 



2 5 6° '5, and on analysis gave the following numbers : — 



Analysis. 



0-2786 f 0-1487 H 2 = 0016522 H= 593 per cent, 



gave <j 0680Q C q 2=0 . 185454 C =6656 „ 



Obtained. Calculated for (C 7 H 7 ) 3 PSe 



Carbon, .... 6656 6596 



Hydrogen, . . . 5'93 549 



The selenium compound decomposes slowly on exposure to light. 



Action of the Haloid Compounds of Benzyl on the Primary Phosphine. 



Action of Benzyl Iodide on Monobenzyl Phosphine. — We investigated this action 

 chiefly with the view of obtaining dibenzyl phosphine, but also with the object of 

 obtaining from it tribenzyl phosphine, by the further action of benzyl iodide. 



We naturally anticipated that if the reaction between the two substances occurred at 

 all it would be of the usual kind, and would at once give rise to a simple product. Experi- 

 ment has, however, shown that such is not the case, as the following results show. 



Experiment 1. — 6 grms. of crystallised benzyl iodide* were placed in a tube, which 

 was then filled with carbonic anhydride, and 5 grms.t of the primary phosphine were 

 added. The tube was sealed and the mixture agitated, when the benzyl iodide liquefied, 

 and a turbid fluid resulted (probably from a trace of water in the benzyl iodide). After 

 about ten minutes the mixture solidified to a snow-white crystalline mass, but no sensible 

 rise of temperature occurred. The tube was opened after two days, and the hard solid 

 mass which it contained broken up, and treated with washed and distilled ether. The 

 ether was, however, not sufficiently dry, and as a consequence the mass became pasty from 

 absorption of water. It was then thrown into a filter, which was placed in a desiccator 

 in vacuo. It soon became hard and brown at the edges. 



It was found that boiling chloroform dissolved the product, and that crystals — pre- 

 sumably of hydriodate of dibenzyl phosphine — separated on cooling. Accordingly, the 

 whole was dissolved in boiling chloroform, but on cooling only a very small quantity of 

 crystalline matter was obtained. 



Moreover, on evaporating off the chloroform, no solid product remained, but only a 

 viscous liquid, from which we did not succeed in obtaining any definite substances. 



Experiment 2. — 12 grms. of the primary phosphine of boiling point 170°-190° C. 



* Prepared by a very simple method discovered by us, namely, by saturating benzyl alcohol with dry hydriodic acid 

 and washing the product with water when it solidifies. The yield appears to be quantitative. 



t A large excess of the primary phosphine was therefore employed, as the molecular weight of C-H-I is 218, while 

 that of ( ' 7 H-PH 2 is 124 ; so that, roughly speaking, 2 parts of the former is required for 1 of the latter. 



