192 PROFESSOR LETTS AND N. COLLIE ON THE 
When the reaction is at an end only a few black particles are visible—the 
solid portions of the product appearing of a dirty orange colour. 
The preceding table shows the results of our experiments on the influence 
of the conditions which affect the yield of chloride of tetrabenzyl-phosphonium, 
which no doubt will be serviceable in experiments on the phosphines of other 
radicals. 
Extraction of Chloride of Tetrabenzyl-Phosphonium from the Product. 
The product of the reaction we have just described consists of a mixture of 
common salt, a small quantity of phosphide of sodium which remains unacted 
on, xylol, chloride of benzyl, and phosphorised bodies, of which the chief is the 
chloride of tetrabenzyl-phosphonium. 
To extract the latter we have tried several different processes, the simplest 
and best of which is the following :— 
The flask containing the product of the reaction is connected with a con- 
denser, and heated in an oil bath at a temperature of 180°-200° C.* as long as 
liquid distils. The mass. remaining in the flask is then detached by a glass 
rod, and added by small portions at a time to cold water acidulated with 
hydrochloric acid; but as spontaneously inflammable phosphuretted hydrogen is 
evolved, the operation must be conducted cautiously. When this gas ceases to 
come off, the solution is filtered and the residue boiled with a considerable 
quantity of water (2 or 3 litres). The aqueous extract is then filtered (through 
a cloth filter), more water is added to the residue, and the two boiled together 
as before, the solution filtered, and this treatment repeated until a portion of 
the extract gives no crystalline precipitate when cooled and mixed with hydro- 
chloric acid. The united aqueous extracts are then mixed with about 10 per 
cent. of their volume of strong hydrochloric acid and allowed to cool. Almost 
every trace of chloride of tetrabenzyl-phosphonium is then precipitated in the 
form of minute needles. The compound is collected on a linen filter, well 
squeezed to free it from mother liquor, and recrystallised from boiling water, 
from which it separates on cooling in beautiful needles often an inch and a half 
long, and almost perfectly white and pure. The residue which remains after ex- 
tracting the phosphonium compound forms a reddish-brown insoluble solid mass. 
It contains phosphorised bodies, the nature of which we shall consider later. 
Chloride of Tetrabenzyl-Phosphonium.—As this body forms the starting 
point from which the other salts of the phosphonium are obtained, we have 
examined its properties very carefully. It is sparingly soluble in cold water. 
(In a rough experiment 100 cc. of water at ordinary temperatures dissolved 
0°35 grm.) It is much more soluble in boiling water, and crystallises from 
* A higher temperature must be avoided, as we find that it materially diminishes the yield of phos- 
phonium salt. 
