68 Proceedings of Eoyal Society of Edinhiirgh, [dec. 19 , 
steam, a stream of carbonic acid passing through the apparatus to 
prevent oxidation. 
Under favourable circumstances, from 60 to 70 grms. of the 
impure primary phosphine were obtained from 360 grms. of benzyl 
chloride. 
The residue in the distilling flask usually consisted of a slightly 
brown viscous mass, which solidified on cooling. It contained the 
secondary phosphine and several bye-products. The water in the 
distilling flask along with it also contained phosphorised bodies. 
After various experiments, we found that the best method for 
isolating the secondary phosphine is as follows : — 
The mass is boiled several times with water until the latter ceases 
to extract zinc salts. It is then boiled with strong potash solution, 
which removes a further quantity of zinc salts, and after washing 
with water it is extracted with boiling spirit, in which most of it 
dissolves ; leaving, however, a small quantity of a black viscous 
syrup. 
The alcoholic solution on evaporation yields crystals of crude di- 
benzyl phosphine, which may be purified by recrystallisation from 
spirit. The mother liquors on further evaporation yield, in addition 
to more of the crude dibenzyl phosphine, a viscous substance which 
contains phosphorised bodies. 
In addition to mono- and di-benzyl phosphine we obtained the 
following bye-products : — 
(A) A crystalline substance precipitated on addition of hydro- 
chloric acid to the potash solution used to extract the viscous mass 
containing dibenzyl phosphine. 
(B) A viscous substance remaining in the alcoholic mother liquors 
after the di-benzyl phosphine had crystallised out. 
(C) A solid substance separating from the aqueous solution 
obtained by treating the contents of the sealed tubes with water. 
(D) A crystalline zinc salt also contained in the aqueous solution, 
from which (C) bad been separated. 
In this paper we shall first discuss the properties of mono- and di- 
benzyl phosphine, and afterwards the nature of the bye-products. 
Monobenzyl Phosphine . — Hofmann purified the crude phosphine 
obtained by distilling the contents of the sealed tubes with water by 
fractional distillation only. He states that, after two distillations in 
