DR. E. FRANKLAND’S RESEARCHES ON ORGANO-METALLIC BODIES. 
263 
When all is prepared for the distillation of the zincethyl, the reservoir D being- 
filled with carbonic acid, and the tube i from the digester (which latter still remains 
in the oil-bath and gas-stove) inserted into the tubulure of the retort g, the stream 
of carbonic acid, which has hitherto flowed through f, is cut off at e' by a caoutchouc 
valve, and is thus made to flow through g, making its escape between the tubulure 
and the tube i. After the carbonic acid has taken this route for a sufficient length 
of time to ensure the complete expulsion of air from g, a piece of sheet caoutchouc is 
passed round the tubulure of g and the tube i, so as to make the union gas-tight, 
whilst at the same moment an assistant opens the caoutchouc valve e'; thus allow- 
ing the carbonic acid again to escape through f. The retort g is thus connected 
with a reservoir kept constantly filled with pure and dry carbonic acid, which 
effectually excludes atmospheric oxygen and moisture from g during the distillation. 
Heat being now applied to the digester, by means of the gas-stove and oil-bath, 
ether begins to distil over, so soon as the temperature of the digester exceeds the 
boiling-point of that liquid. The first half-ounce is nearly free from zincethyl and 
might be collected apart, but I generally prefer to receive the whole product of the 
distillation in one vessel. As the temperature rises to 140° or 150° C. the product 
becomes more and more rich in zincethyl, but a heat of 190° C. is required to bring 
over the last portions of this body, a large quantity of which is apparently in some 
form of combination with the iodide of zinc, and can only be expelled at a very 
much higher temperature than the boiling-point of zincethyl. During the last 
stages of the distillation, there is a slow evolution of gas, due to the decomposition of 
a small portion of the zincethyl by tlie high temperature required for its complete 
expulsion. 
After the whole of the volatile products have passed over, the tube i must be 
carefully withdrawn from g and immediately replaced by a thermometer passing 
through a well-dried cork. The beak of the retort, disconnected from the tube h, 
must now be inserted air-tight into a suitable tubulated receiver, previously filled with 
dry carbonic acid, the tubulure of which is connected with the carbonic acid receiver 
D, and the rectification may now be commenced. The liquid begins to boil at 
