1887.] Prof. Letts and W. Wheeler on Benzyl Pliospliines. 67 
properties. He mentions that bye-products are formed along with 
them which he did not further investigate. 
We have repeated Hofmann’s experiments, and have submitted 
both the mono- and di-benzyl phosphine to a very careful examina- 
tion. We have also investigated the bye-products which are formed 
and have determined as far as possible their composition. 
Preparation of Mono- and Di-Benzyl Phosphine. — Hofmann 
recommends digestion during six hours at 160° C. of a mixture 
of 4 parts of oxide of zinc, 16 of iodide of phosphonium, and 
12 of chloride of benzyl. Experiments conducted in this way 
with commercial chloride of benzyl from Kahlbaum gave in the 
tubes a viscous semicrystalline mass. To obtain a good result, 
thorough mixing of the materials in the sealed tubes by shaking 
before heating seemed to be necessary. On opening the tubes much 
phosphuretted hydrogen escaped, but on heating for a longer period 
or to a higher temperature, the escaping gas seemed to consist of 
hydrochloric acid only. It was soon found that at the temperature 
of 160° C., a great deal of hydrochloric acid is formed, and but 
little of the primary phosphine. The best results were obtained 
by a six hours’ digestion of the mixture at temperature of 120° C. 
Experiments tried at 100° to 110° C. showed that but little of the 
primary phosphine is formed. 
With the quantities Hofmann recommends and a digestion for 
six hours at 120°, the tubes when cold contain a viscous semi- 
transparent mass, sometimes of a brown colour, sometimes red and 
opaque from the separation of free phosphorus. Above this a 
small quantity of a liquid usually floats, which at times is mobile, 
but at others thick and slightly fluorescent. A few crystals of 
undecomposed iodide of phosphonium are also frequently present. 
The liquid floating on the viscous mass (consisting of benzyl 
chloride, toluol, &c.) we usually poured off, whilst the viscous mass 
itself we removed by inverting the tubes and blowing a current of 
steam through them — the operation being so conducted that no air 
was admitted, whilst the viscous mass (which liquefies when warmed) 
was allowed to run into a distilling flask — without coming in con- 
tact with the air. 
The crude primary phosphine (liberated by the action of water 
on the product of the reaction) was then distilled off in a current of 
