74 Royal Society. 
and 3'5 hydrogen, instead of 13°9 carbon and 3:0 hydrogen. After 
all, an analysis is not necessary to enable us to arrive at the composi- 
tion of this body. The products formed by the action of potash on 
it furnish us with almost as convincing a proof of its composition as 
any analysis could do. They are iodide of potassium and oxide of 
ethylene. 
Iodhydrine of glycol is soluble in water and alcohol, but insoluble 
in ether. It has no taste at first; after a time, however, it almost 
burns the tongue, it is so pungent. It is decomposed by heat into 
iodide of ethylene, and probably glycol. It acts with great energy 
on the salts of silver. 
Action of Hydriodic and Acetie Acids on Glycol.—Formation of 
Iodacetine of Glycol. 
A stream of hydriodic acid gas was conducted into a mixture of 
equivalent quantities of glacial acetic acid and glycol, the tempera- 
ture of which was prevented from rising during the action of the gas. 
As soon as a portion of the liquid gave a considerable quantity of an 
oily precipitate on the addition of water, the passage of the gas 
was interrupted ; for the prolonged action of the gas is apt to give 
rise to the formation of iodide of ethylene. The liquid thus obtamed 
was well washed with very dilute potash, dried i vacuo, and ana- 
lysed. The numbers obtained lead to the formula c Ht O. \ O., as 
will be seen from the following Table :— ‘i 
Theory. Experiment. 
ta Il. 
icc... cee 21°95 22°30 
Bo e597 3°31 3°50 
O, 14:96 bf me 
I 59°35 
100°00 
Todacetine has a sweetish pungent taste. It is insoluble in water, 
but soluble in alcohol and ether. Its specific gravity is greater than 
that of water. It crystallizes in tables when exposed to cold. Heated 
with potash, it gives iodide of potassium, acetate of potash, and oxide 
of ethylene. It is readily decomposed by the salts of silver. 
This compound can also be prepared with great facility by ex- 
posing monoacetate of glycol to the action of hydriodic acid gas. 
The liquid must be kept cold during the action of the gas, which 
should be interrupted as soon as the addition of water to a portion 
of it causes an abundant oily precipitate. The whole is then washed 
with dilute potash, and dried iz vacuo. A specimen prepared in 
this manner gave, on analysis, 22°62 per cent. carbon and 3°43 hy- 
drogen, instead of 22°42 carbon and 3:27 hydrogen. 
I hope soon to have an opportunity of studying these iodine com- 
pounds more particularly. 
