BENZYL PHOSPHINES AND THEIR DERIVATIVES. 545 



methods to those which we employed for preparing the two compounds just described. 

 On passing gaseous hydrochloric acid into a solution of the phosphine in benzol no effect 

 is produced until saturation is complete, then colourless crystalline scales begin to 

 form. On shaking the phosphine with a saturated aqueous solution of hydrochloric acid, 

 a similar precipitate is produced. We have not analysed the compound, as we did not 

 obtain it in sufficient quantity, but its composition cannot be doubted. 



Chloroplatinate. — On mixing the phosphine with an aqueous or alcoholic solution of 

 chloride of platinum, a light yellow bulky amorphous precipitate is produced. We did 

 not analyse it. 



Action of Air or Oxygen on Monobenzyl Phosphine. — As we have before mentioned, 

 the phosphine attracts oxygen with great energy from the air, the temperature rises 

 considerably, dense white vapours are produced which occasionally take fire spontaneously. 

 The final product of the oxidation is a colourless viscous liquid which refuses to crystallise. 

 It dissolves somewhat sparingly in water, and has a strong acid reaction. 



On adding acetate of lead to its aqueous solution a white flocculent precipitate is 

 produced which is by no means quite insoluble, so that its bulk diminishes considerably 

 on washing. The following results were obtained on submitting it to analysis : — 



Analysis. 



I. 01060 gave 00925 PbS0 4 = 06319 Pb = 5960 per cent. 

 II. 04538 „ 0-4035 „ =275 Pb = 608 



I. Prepared from the phosphine obtained from its hydriodate. 

 II. Prepared from the crude phosphine. 



Obtained Calculated for 



^ ^p (CVHyHPO^Pb (C 7 H 7 )P0 3 Pb 



Lead, . . 596 60-8 3992 54-97 



It is obvious that the lead salt is neither the benzyl-phosphinite nor benzyl 

 phosphinate. On the other hand, the percentage of lead does agree fairly well with 

 that required for the formula (C 7 H 7 )PO.Pb — viz., 60 - 0, and this view of its composition, 

 namely, that it is a derivative of an oxide C 7 H 7 PH 2 in which the two atoms of hydrogen 

 are replaced by one atom of lead, unlikely as it appeared, was supported by the increase 

 in weight which a sample of the pure phosphine experienced on spontaneous oxidation — 

 a rough experiment giving 14*1 per cent, increase in weight, instead of 12 '9 per cent., the 

 calculated amount. 



At the time of our first experiments on this subject we were unacquainted with 

 benzyl phosphinic acid, and hence knew nothing about the properties of its lead salt or 

 of its other compounds. After it had been obtained, however, and its salts investigated, 

 a simple means was at our disposal for ascertaining whether it was present in the product 

 of oxidation of the primary phosphine, and for separating it if necessary from other 

 substances. For benzyl phosphinate of barium is a highly characteristic salt, being 

 much less soluble in boiling water than in cold, and is precipitated almost completely 



