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



The rest of the product was washed with dry ether, and then decomposed by potash 

 in a flask through which a stream of hydrogen flowed. A current of steam was then passed 

 to complete the decomposition, and to drive off any volatile matters. The aqueous 

 solution was then decanted, and the oily liquid reserved for examination. 



(1) On mixing some of this liquid with iodide of benzyl in excess, much heat was 

 disengaged, and on cooling a viscous mass resulted. This boiled with caustic potash 

 gave a solid substance, and on crystallising the latter from alcohol two sets of crystals 

 were obtained, one having the characteristic form of iodide of tetrabenzyl phosphonium, 

 the other that of tribenzyl phosphine oxide. 



(2) The rest of the oily liquid was left for some time and became semisolid. On 

 treating this with ether, a white crystalline solid remained undissolved, which was 

 apparently oxide of tribenzyl phosphine. The ethereal solution filtered from this was 

 distilled off in a stream of hydrogen, and left about 10 grms. of a colourless liquid, which 

 was distilled in vacuo. 



It behaved in exactly the same manner as described with the corresponding liquid 

 obtained in Experiment 2 ; that is to say a little liquid distilled over — say about one-third 

 of the original quantity operated on — and the residue then showed unequivocable signs 

 of decomposition with separation of red phosphorus. The distillate was mixed with the 

 corresponding distillate described under Experiment 2, and the mixture submitted to an 

 oxidation experiment conducted quantitatively. 



1*3995 grms. were weighed out in a sealed tube and transferred to a beaker. Dense 

 white fumes were produced at first, and a syrupy liquid resulted. After twelve hours, 

 baryta solution was added, and the mixture evaporated to dryness several times, with 

 addition of water. The aqueous solution was then filtered and mixed with hydrochloric 

 acid, when a crystalline precipitate of dibenzyl phosphinic acid was produced, which weighed 

 when dry 0'0912 grms. The residue insoluble in water was treated with a little hydro- 

 chloric acid to remove carbonate of barium, then washed and dried. Its weight amounted 

 to 0*1098 grms. It consisted mainly at all events of oxide of tribenzyl phosphine.* 



The filtrate from the dibenzyl phosphinic acid and the hydrochloric acid washings 

 from the oxide of tribenzyl phosphine were evaporated on a water-bath to drive off 

 excess of hydrochloric acid, the residue neutralised with baryta, and again evaporated to 

 dryness, and extracted with alcohol. The alcoholic extract when dry weighed 0*3786 

 grms. This residue gave all the characteristic reactions of benzyl phosphinite of barium, 

 and was considered to be that substance. The residue from the alcoholic extraction was 

 dissolved in water, and the solution boiled, when the characteristic crystals of benzyl 

 phosphinate of barium were precipitated. 



These results prove that the distilled liquid was chiefly monobenzyl phosphine 

 mixed with smaller quantities of dibenzyl and tribenzyl phosphine. 



* The dibenzyl phosphinic acid was identified by its melting point (191 -5-192 ) after recrystallisation. The oxide 

 of tribenzyl phosphine by its characteristic crystalline form and by the production of its crystalline compound with 

 bromine in acetic acid. 



