[4.15 ] 



LXVIII. On Iodic Mther. By James F. W. Johnston,M.^. 

 RR.S. E. $c. $c* 



"IX/'HEN a saturated solution of iodine in alcohol is poured 

 * * into hot nitric acid in a large flask, a violent action takes 

 place with evolution of nitric aether, acetic acid and deutoxide 

 of azote; and the colour of the iodic solution disappears. If 

 the heat be kept up, and iodine in a solid state be gradually 

 added as long as the action takes place, and the colour disap- 

 pears, there is deposited on cooling a transparent yellowish 

 oily-looking fluid, heavier than water, and possessing the fol- 

 lowing properties: — 



1. It has a strong penetrating odour, very different from 

 that of the hydriodic aether of Gay-Lussac, and a sharp burn- 

 ing taste, the effect of which remains upon the tongue for a 

 considerable time. 



2. When free from excess of iodine it is of a very pale 

 yellow colour; a slight heat, however, discolours it by causing 

 partial decomposition. 



3. It is not easily inflammable. It cannot be volatilized 

 without decomposition. The heat and light of the sun decom- 

 pose it in close vessels ; it becomes coloured and deposits iodine 

 in regular crystals. Kept in contact with the acid liquid in 

 which it was originally formed, it remains colourless for a great 

 length of time. Left to spontaneous evaporation in the open ail 

 it thickens, becomes discoloured, and disappears very slowly. 

 On the hand it volatilizes rapidly, and leaves a stain like io- 

 dine. 



4. Its specific gravity at 60° Fahr. is about 1*34. 



5. The boiling point of the compound is as high as 230° 

 Fahr. When gradually heated in a small retort, a colourless 

 fluid, having an aethereal odour, begins to distill over as low 

 as 160°; while the aether in the retort gradually thickens and 

 becomes dark coloured. At 380° this coloured liquid comes 

 over very slowly in brownish red fumes, which condense in the 

 beak of the retort into a dark brown solid, consisting chiefly 

 of iodine. Over a spirit-lamp the distillation and decomposi- 

 tion are much more rapid ; iodine is given off in copious violet- 

 coloured vapours, and there remains a light shining charcoal, 

 which in the flame of a candle burns away very slowly. The 

 clear liquid which distills over by a gentle heat reddens litmus, 

 but gives no aether by admixture with water. 



In preparing this aether, if we continue the heat after the 

 iodine has disappeared without adding more, the aether held 

 in solution by the acid liquid is again decomposed, the solu- 



* Communicated by the Author. 



