BENZYL PHOSPHINES AND THEIR DERIVATIVES. 577 



(.D). A crystalline solid of low melting point remaining in the alcoholic mother-liquors 

 from which oxide of tribenzyl phosphine had crystallised out. (This substance we call 

 "Crystalline Oil".) 



We obtained all of these bye products in our earlier experiments, in which after 

 steaming the contents of the sealed tubes with water to liberate the primary phosphine, 

 the residual viscous insoluble mass was boiled with aqueous potash. 



In our later investigations other bye products were obtained, but we shall first discuss 

 the composition of the first three we have just enumerated. 



A. Crystalline Substance precipitated by Hydrochloric Acid from the Potash Solution 

 used for extracting the viscous mass containing Tribenzyl Phosphine, &c. — This body 

 was precipitated in crystalline flocks. It was very sparingly soluble in cold water, 

 rather more so in hot water, and crystallised from a boiling aqueous solution in indistinct 

 leaflets. That the substance had acid properties was proved by the readiness with which 

 it dissolved in potash and baryta solutions. A slight residue was, however, left in 

 both cases, and indeed an impurity appeared to be present which was extremely difficult 

 to eliminate, as the following analyses show. 



Analysis. 



Obtained. 



I. 

 i, . . 59-69 

 jen, . . 5-80 



A. 

 II. 



66-30 

 630 



III. 



6706 



6-50 



Calculated for 

 (C 7 H 7 ) 2 P0 2 H 

 68-29 

 609 



(1) Crude product washed with water. 



(2) Precipitated from a solution of the crude product in baryta, and carefully washed. 



(3) Several times dissolved in baryta and reprecipitated by hydrochloric acid, then recrystallised from alcohol and water. 



The identity of the substance was, however, fully established by analyses of some of 

 its salts. 



Barium Salt. — Obtained by dissolving the crude product in baryta water, and 

 subsequent precipitation of the excess of baryta by a stream of carbonic anhydride. 

 The salt crystallised from the highly concentrated solution in tufts of thin plates. 



Analysis. 



Obtained. ,-, , ■, . , c 



Calculated tor 



L ~~ iT {(C 7 H 7 ) 2 P0 2 } 2 Ba 



Barium (in salt dried at 110), 22-2 21'8 21-8 



Zinc Salt. — Obtained as a white amorphous precipitate on adding acetate of zinc to a 

 solution of the barium salt. 

 Analysis. 



,-.,, ■ i Calculated for 



Obtained. { (C 7 H 7 ) 2 P0 2 } 2 Zn 



Zinc, . . . . 121 11-7 



Silver Salt. — Obtained by adding a strong solution of nitrate of silver to a solution 

 of the acid in alcohol, when the salt separated in thin colourless needles. 



