Mr. J. F. W. Johnston on Iodic Mther. i 1 7 



ease with which water and the caustic and carbonated alkalies 

 discolour and partially decompose it, and the impossibility ol' 

 distilling it, 1 have not hitherto obtained it in a state, in which, 

 in the air at least, it does not possess this property in a slight 

 degree. A weak solution of caustic potash or soda acts upon 

 it like water, discolouring it and diminishing its volume ; but 

 after washing again with water to remove the alkali a slight 

 action upon litmus is still observable. This is to be ascribed 

 solely, I believe, to partial decomposition. A concentrated 

 solution of a caustic fixed alkali acts upon it, with the evolution 

 of heat and some gas; and when allowed to subside after 

 agitation the alkaline solution is of a red colour, and the aether, 

 much diminished in quantity, is colourless, or nearly so. Agi- 

 tated with pure water the aether again becomes coloured and 

 tinges litmus. With a sufficient excess of caustic alkali it ap- 

 pears, like muriatic aether, to be resolvable into a colourless 

 oil containing only carbon and hydrogen. 



The alkaline solution evaporated to dryness, and the dry 

 salt redissolved gives no trace of iodic acid. It precipitates 

 lead of the well-known yellow colour, but it does not precipi- 

 tate muriate of barytes. Nitric acid separates iodine from the 

 solution. 



10. After being treated with caustic potash in a concen- 

 trated solution, potassium has a very slight action upon it, 

 becoming tarnished, evolving minute bubbles of gas, and 

 making the liquid slightly brownish. If potassium be dropped 

 into the aether as first obtained, much action and evolution of 

 heat takes place, aether and an iodide are formed, and char- 

 coal remains behind. 



11. When dry phosphorus is thrown upon it considerable 

 action takes place, with evolution of heat, and an iodide of 

 phosphorus is formed. The same takes place under water, and 

 the supernatant liquid contains hydriodic acid, from which ni- 

 tric acid precipitates the iodine. On sulphur it has no action. 



12. Mercury does not act upon it in the cold, unless the 

 aether have become discoloured by partial decomposition, when 

 the mercury removes the free iodine to which the colour is 

 due. When slightly heated a greenish pellicle is formed on 

 the mercury, and the colour developed in the aether by heat 

 disappears. This greenish pellicle dried and heated becomes 

 red, showing that some iodide had been formed. The decom- 

 position, however, is due to the heat and not to the action of 

 the mercury. 



This aether may also be prepared by the substitution of sul- 

 phuric aether for alcohol, in which case, after the violence of 

 the action has ceased, the bottle may be placed in the sun 

 Third Series. Vol. 2. No. 12. June 1833. 3 H 



