298 PROFESSOR LETTS ON PHOSPHORUS-BETAINES, 
and to be capable of yielding the bodies in any quantity that may be desired. 
This method consists in heating methyl or ethyl alcohol with iodide of phos- 
phonium for some hours in a sealed tube at 180° C., when a mixture of 
hydriodate of triethyl-phosphine and iodide of tetrethyl-phosphonium results, 
from which caustic potash separates triethyl-phosphine in the pure state. 
The author has been unsuccessful in his attempts to prepare trimethyl- and 
triethyl-phosphine in quantity by this process, although he has repeated the 
experiment between thirty and forty times with every precaution. The sealed 
tubes almost always exploded, and only in two or three cases did this not 
occur. He was therefore compelled to abandon this method, and to resort to 
the earlier process for preparing a tertiary phosphine. This was discovered by 
Hormann and Canours,* and consists in treating a zinc ether with terchloride 
of phosphorus. The method is at least certain, although tedious and trouble- 
some ; and as zinc methyl is difficult to obtain ona large scale, it was necessary 
for the author to confine his experiments to the ethyl series. 
As he has made very large quantities of triethyl-phosphine by this process, 
and his experience may be of use to others who may have occasion to prepare 
it, he thinks it better to describe the exact method of procedure which he 
adopted. 
Zinc-Ethyl.—This was prepared by means of the zinc copper couple, which 
GLADSTONE and TrIBEt have shown to give very good results on the small scale. 
The author has made a very large number of experiments with this method, 
and always with complete success. The process is simple and easily carried 
out, and the yield of zinc-ethyl is very good. The author can strongly 
recommend it for the preparation of large quantities of that substance. 
The zine for the couple was always prepared by pouring the molten metal 
into an almost red hot iron mortar, stirring and pounding as rapidly as possible. 
With a little practice, it is easy to manipulate almost 16 kilogrammes of zine in 
a couple of hours, and to obtain it as a very fine powder. 
This fine powder is sifted from the coarser particles by means of a wire- 
gauze sieve—the gauze being of the usual size employed as a support when 
heating beakers, &c. 
The copper was obtained by the reduction of the ordinary powdered oxide 
of commerce in a stream of hydrogen. It was sifted through the same sieve as 
was employed for the zinc. 
The couple was prepared as GLADSTONE and TRIBE recommend. 
One part of powdered copper and nine parts of zinc powder are placed in a 
flask and heated over a large Bunsen’s burner with constant shaking until the 
particles begin to accumulate in small lumps. Great care is necessary to obtain 
* Trans. Roy. Soc. Lond., 1857. 
+ GuapstoneE and Tripp, Journ. Chem. Soe., 1879. 
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