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



acid, and we had already had some evidence of its presence there. We searched for it 

 by the following method : — 



The mother-liquors remaining, after the phosphinic acid had been separated as far 

 as possible by concentration and crystallisation, were diluted and mixed with excess of 

 acetate of lead. The insoluble lead salts produced (chiefly iodide and phosphate) were 

 filtered off and the excess of lead removed by a current of sulphuretted hydrogen. The 

 solution was filtered and evaporated until all acetic acid was driven off, and nothing but a 

 syrupy liquid remained, which gave off benzyl phosphine on heating. The investigation 

 of this syrup, which evidently contained the phosphinous acid, proved troublesome. A 

 portion was neutralised with chalk and evaporated to small bulk, when a salt separated 

 in crystalline crusts. 



Analysis. 



0-3965 (dried at 110° C.) gave 0-0768 CaO=0-0548 Ca = 13-82 per cent. 



Obtained. Calculated for { (C 7 H 7 )HP0 2 },,Ca 



Calcium, . . . . ■ . 13-82 11-42 



This showed that the calcium salt was not pure. 



The rest of the syrup was neutralised with baryta and evaporated to small bulk, 

 when the solution crystallised on cooling, and apparently two sets of crystals were formed. 

 They were dried as far as possible by pressure, dissolved in a very little water, and then 

 alcohol was added to the solution, when a crystalline salt was precipitated. This was 

 washed and analysed. 



Analysis. 



06294 (dried at 110° C.) gave 05456 BaSO 4 = 0-3208 Ba = 5096 per cent. 



Obtained. Calculated for (PH 2 2 ) 2 Ba 



Barium, 50-96 51-31 



The salt gave all the reactions of a hypophosphite. Heated, it evolved phos- 

 phuretted hydrogen ; boiled with sulphate of copper, the copper was reduced, &c. 



The mother-liquors from which it had separated gave on evaporation in the desiccator 



a cake of crystals. Some of these were drained on filter-paper, then dried at 110° C. until 



they were of constant weight. 



Analysis. 



0-5564 gave 0-3251 BaSO 4 =01911 Ba=34-34 per cent. 



Obtained. Calculated for {(C 7 H 7 )P0 3 H} 2 Ba 



Barium, 3434 30-64 



A solution of this salt behaved with acetate of copper in the manner so characteristic 

 of benzyl phosphinite, giving a greenish precipitate in a strong solution, no precipitate 

 in a weak solution, but an immediate green precipitate on boiling. Moreover, the mother- 

 liquors from tlie copper salt obtained from a strong solution deposited the green salt 

 immediately on boiling. 



