120 



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 other 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 



4 4 2 discovered bv M - Wurtz - A portion of this liquid, 



4 1 2 ) di 

 Cl 



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. After the analysis, however, I discovered 

 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, 1 1 I per cent, carbon 

 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 cf 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 Acetic Acids on Glycol. Formation of 

 lodacetine 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 



