1887.] Prof. Letts and W. Wheeler on Benzyl Phosphines. 81 
Zinc Salt . — Obtained as a white amorphous precipitate on adding 
acetate of zinc to a solution of the barium salt : — 
Calculated for 
Obtained. {{C^HjisPOj I^Zn 
Zinc. . . . 12-1 ■ 11-7 
Silver Salt . — Obtained by adding a strong aqueous solution of 
nitrate of silver to a solution of the acid in alcohol, when the salt 
Calculated for 
{(C^H, bPO^ }Ag. 
30-6 
Although the analyses of the acid itself are not very satisfactory, 
the composition of its salts shows pretty conclusively that it is di- 
benzyl phosphinic acid. This is also proved by its artificial pro- 
duction from dibenzyl phosphine, as we shall presently explain. 
Dibenzyl phosphinic acid has the following properties ; — 
It is very sparingly soluble in water, but readily dissolves in hot 
alcohol. Drom a mixture of the two it crystallises in thin scales 
with mother-o’-pearl lustre. Its melting point is 183°-186° C. 
Its salts with the alkalies and alkaline earths are readily soluble, 
whilst those which it forms with lead, zinc, and silver are very 
sparingly soluble. 
Production of Dibenzyl Phosphinic Acid from Dihenzyl Phos- 
phine . — When dibenzyl phosphine is heated with caustic potash or 
soda it fuses and floats on the surface of the melted alkali. No 
violent action occurs, but on cooling the mixture and treating it 
with water, the greater portion dissolves, and acids then precipitate 
a flocky crystalline substance, which is dibenzyl phosphinic acid, as 
the following data prove : — 
Melting point after two recrystallisations from a mixture of 
alcohol and water, 186° *5 C. 
Obtained. Calculated. 
Carbon, . . . 67T 68‘3 
Hydrogen, . . 6 '5 6T 
Lead Salt— 
Lead, . . . 30*5 29 '7 
Barium Salt — (dried at 110° C.) 
Barium, . . 22-0 21*8 
VOL. XV. F 
separated in thin colourless needles : — 
Obtained. 
Silver, . . 30T 
