Dr. Simpson on the Action of Acids on Glycol. 73 
pungent and somewhat bitter taste. It is insoluble in water, but 
freely soluble in alcohol and ether. Boiling solution of potash 
effects its decomposition with difficulty, solid potash readily, the re- 
action being the same as in the case of the analogous compounds, 
Action of Hydriodic Acid on Glycol.—Formation of Iodide of 
Ethylene and Iodhydrine of Glycol. 
Hydriodic acid gas is absorbed with great energy by glycol. A 
considerable quantity of heat is evolved during the passage of the 
gas, and the liquor becomes black and thick from the separation of 
free iodine. On removing the iodine by means of dilute potash, a 
mass of small white crystals is brought to light, which I at once 
suspected to be iodide of ethylene. To remove all doubt on this 
point, I submitted the crystals to analysis, having previously purified 
them by recrystallizing from boiling alcohol. The numbers ob- 
tained agree, with the formula of iodide of ethylene :— 
Theory. Experiment. 
ae 8°73 
BER cary AAP 1-78 
Bo2sj.:hg SPLOT ais 
100-00 
The reaction which causes the formation of iodide of ethylene may 
be thus explained :— 
C,H 
H 
That the action of hydriodic acid on glycol should be different 
from that of hydrochloric acid is doubtless owing to the bond of 
union between hydrogen and iodine being much weaker than that 
between hydrogen and chlorine. 
If, on the otaer hand, the temperature of the glycol be prevented 
from rising during the passage of the hydriodic acid gas, by sur- 
rounding the vessel containing it with cold water, a liquid product is 
obtained, which is coloured dark-brown by free iodine. This I have 
not as yet been able to discover any means of purifying, it being 
soluble in water, and decomposed by distillation. I believe, how- 
ever, it is the compound corresponding to chlorhydrine of glycol 
(“s a 0,) discovered by M. Wurtz. A portion of this liquid, 
1 
from which I had simply removed the free iodine, by agitation with 
mercury, gave, on analysis, numbers agreeing tolerably well with the 
formula of iodhydrine of glycol. After the analysis, however, I dis- 
covered that it contained a considerable quantity of iodide of mercury 
in solution. Another portion, from which I had removed the iodine 
by means of metallic silver, gave, on analysis, 11°] per cent. carbon 
st O,+2HI=C, H, 1,44HO. 
