188 PROFESSOR LETTS AND N. COLLIE ON THE 
Benzyl-phosphine is formed, according to the reaction, 
2C,H,Cl+2(H,PHI) + ZnO =2|(C,H,)H,PHT], ZnCl, + HO. 
This equation, however, only expresses one phase of the reaction, in which 
simultaneously with monobenzyl-phosphine other products are formed. Of 
these Hormann could only succeed in isolating— 
Dibenzyl-Phosphine.—This compound is contained in the residues after 
the benzyl-phosphine has been distilled off. On long standing in contact with 
solid potash, these solidify to a soft crystalline mass, which is collected on a 
linen filter, well squeezed, dissolved in alcohol, and the solution decolorised 
with animal charcoal. It then deposits, on cooling, beautiful white crystals 
of the dibenzyl-phosphine, which only require to be recrystallised from alcohol 
to obtain them in a state of purity. 
Dibenzyl-phosphine thus obtained forms glistening white needles of large 
size, which are tasteless and colourless. They are insoluble in water, spar- 
ingly soluble in cold alcohol, readily in hot alcohol. The crystals melt 
at 205°, and sublime at higher temperatures, but not without partial decom- 
position. . 
With the introduction of the second benzyl group the alkaline characters, 
which are perfectly apparent in monobenzyl-phosphine, disappear. 
Dibenzyl-phosphine dissolves in no acid, nor could Hormann obtain its 
chloro-platinate. Its composition could, therefore, only be determined by an 
analysis of the purified substance. The formation of dibenzyl-phosphine may 
be expressed by the equation, 
2C,H,Cl+ H,PHI + ZnO =[(C,H,),HP,HI], ZnCl, + H,0. 
The mother liquors of the dibenzyl-phosphine contain another phosphorised 
body, which Hormann suspected to be tribenzyl-phosphine, but in spite of 
many efforts he was not able to prepare that body. 
