57$ PROF. LETTS AND MR R. F. BLAKE ON 



Analysis. 



,-.,,- , Calculated for 



Obtained. (C 7 H 7 ) 2 P0 2 Ag 



Silver, .... 30-1 306 



Subsequently we obtained dibenzyl phosphinic acid by other methods, and satisfied 

 ourselves that it was identical with the substance in question. 



B. Solid Substance which separated spontaneously from the Aqueous Solution obtained 

 by treating the contents of the Sealed Tubes with Water. — This body separated from the 

 solution as a white powder stained brown by free iodine. On boiling with dilute spirit 

 it dissolved, and the solution on cooling deposited thin colourless plates, which when 

 dried had the lustre of mother-of-pearl. An analysis was not made, as the melting point 

 (192° corr.) and other properties proved sufficiently that the substance was dibenzyl 

 phosphinic acid. It may be mentioned that this body is also produced when chloride of 

 benzyl and phosphonium iodide are heated alone in a sealed tube, the product of action 

 being; afterwards treated with water. 



C. Crystalline Zinc Salt contained in the Aqueous Solution obtained by treating 

 the contents of the Sealed Tubes with Water. — This salt was obtained as follows : — The 

 aqueous solution filtered from B (dibenzyl phosphinic acid) was mixed with excess 

 of acetate of lead (in order to precipitate hydriodic acid), then after filtering from 

 iodide of lead saturated with sulphuretted hydrogen, again filtered and evaporated to 

 small volume. "When most of the acetic acid had volatilised a zinc salt crystallised out in 

 small nodules. Determinations of zinc and water indicated that this salt was benzyl 

 phosphinate of zinc, but it was not obtained in sufficient quantity for further examina- 

 tion. 



Analysis. 



Obtained. Calculated for (C 7 H 7 )P0 3 Zn,H 2 



Zinc, .... 257 257 



Water, .... 6*9 71 



In a later series of experiments a different method of treatment was employed, with 

 the object of obtaining all the bye products of the reaction. 



The contents of the sealed tubes were steamed with water as already described, and 

 the aqueous solution decanted. The brown viscous mass remaining was then steamed a 

 second time with water, and the solution decanted and mixed with the first. The 

 viscous mass, now fairly free from soluble zinc salts and hydracids, was repeatedly 

 extracted with alcohol, when a considerable quantity was dissolved, leaving, however, 

 a resinous mass coloured with red phosphorus. This latter was repeatedly boiled with 

 baryta, and then extracted with chloroform, which dissolved a resin having a strong green 

 fluorescence, and containing phosphorus. We have not succeeded in ascertaining its 

 nature. The alcoholic extracts were thrown into a large volume of caustic baryta solution 

 and boiled for a considerable time, and this treatment repeated with what remained 

 undissolved. The resinous matter at first precipitated became crystalline during the 

 ebullition, and eventually the crystals were found to consist of oxide of tribenzyl phos- 



