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



to remove dibenzyl phosphinic acid. The residue was washed with water and dilute 

 hydrochloric acid, and then boiled with alcohol. The filtered solution gave on cooling a 

 crop of colourless needles, mixed with a few of the red crystals, but by recrystallisation 

 they were obtained pure. They had a melting point of 212° C. (uncorr.), agreeing with 

 that of tribenzyl phosphine oxide, and they also gave the compound with iodide of zinc, 

 microscopically identical with a specimen prepared with a known sample of the oxide. 

 The red crystals we did not obtain in sufficient quantity to examine. 



Experiment 2. — In order to avoid the very violent action which had occurred in our 

 first experiments, we now allowed the benzyl alcohol to drip down the inverted 

 condenser slowly on to the phosphorus mixture from a tap funnel. The first drops 

 occasioned a very violent action, even in the cold, the flask becoming full of white fumes 

 and iodine vapour ; but as more of the benzyl alcohol was added the action moderated, 

 though it continued to be pretty brisk, and sufficiently so to keep the mixture in 

 ebullition. When all the alcohol had been thus cautiously added, and the reaction 

 appeared to be over, a little more of the phosphorus mixture was added, and further 

 action occurred, but it was not very violent. Finally, the flask containing the product 

 of the reaction was heated for some time in an oil-bath and then allowed to cool. 



This product consisted of a dark brown viscid mass. To it a quantity of water 

 was added, when heat was developed. The flask in which it was contained was 

 next connected with a Liebig's condenser, and a current of steam blown through it, when 

 a somewhat brisk action occurred, and an oily liquid distilled over. This was in fairly 

 large quantity, and was readily identified by its boiling point (111° C.) and odour as 

 toluol. The residue in the flask after steaming, consisting of a dark brown oily substance 

 swimming on the surface of the water, rapidly solidified. The aqueous solution was 

 decanted, and the residue (which had by this time completely solidified) was extracted 

 two or three times with boiling water. The aqueous solutions were mixed, and gave on 

 cooling an abundant colourless crystalline precipitate (A). 



The residue after thorough extraction with water was pounded up in a dish and 

 extracted several times with baryta solution, then washed with water, and finally boiled 

 several times with alcohol, until nothing remained apparently but amorphous phosphorus. 

 The alcoholic solutions were evaporated down, and gave on cooling an abundant crop of 

 colourless needles (B). 



The mother-liquors from (A) were pressed out through linen and evaporated until 

 fumes of hydriodic acid came off. They were then allowed to cool, when the solution 

 solidified to a radiating crystalline mass (C). The mother-liquors were squeezed out 

 through linen and heated on a steam-bath for a considerable time, during which they 

 not only fumed, owing to evolution of hydriodic acid, but also effervesced, and the 

 effervescence increased on stirring. On heating some of the liquid in a tube it frothed 

 considerably, and iodide of phosphonium sublimed, while later the odour of monobenzyl 

 phosphine became very distinct and its hydriodate volatilised. 



Examination of Product A. — This was freed as far as possible from adhering mother- 



