'Sh Coiinell on the Acidification of' Iodine. 73 



ceeded to try the process with larger quantities of the materials 

 with a view to its employment as a method for the preparation 

 of iodic acid. The vessel I used was a rather large and tall 

 flask, having a narrow orifice. In one trial I used twenty-five 

 grains of iodine, and half an ounce measure of fuming nitric 

 acid ; and in another, I employed twice these quantities of the 

 materials. After introducing the iodine and acid into the flask, 

 the liquid was made to boil. As soon as any iodine sublimed 

 and condensed on the sides of the vessel, it was washed back 

 again into the liquid by agitation. After the process had been 

 continued some time, a precipitation of white crystalline grains 

 was observed to take place ; and the operation of boiling and 

 washing back the sublimed iodine was continued until the free 

 iodine had to a great extent disappeared. The whole was then 

 decanted into a shallow bas.in, and evaporated to dryness. Any 

 free iodine which had remained was soon dissipated by the heat. 

 The residue of the evaporation consisted of whitish crystalline 

 grains, which were iodic acid, retaining a little nitric acid, from 

 which they appeared to be freed by one or two solutions in 

 water, and re-evaporations, when they lost much of their crys- 

 talline appearance, and became a whitish deliquescent mass, oc- 

 casionally with a slight purplish tint, from a tendency to de- 

 composition by the heat of evaporation. 



The general properties of the matter thus obtained, suffi- 

 ciently identified it with iodic acid. Exposed to a sufficient 

 heat, it was decomposed, and iodine sublimed. Its solution in 

 water gave a precipitate with nitrate of silver, soluble in am- 

 monia. Saturated with potash, it gave by evaporation a salt 

 composed of grouped cubical crystals, and deflagrating on hot 

 charcoal. 



The quantity of the acid obtained by this process, of course, 

 must vary, according to the care taken to prevent the dissipa- 

 tion and loss of iodine. Where no particular precautions were 

 taken to prevent its loss in the state of vapour, and where the 

 process was not continued mitil the entire disappearance of 

 iodine, the quantity of acid obtained approached that of the 

 iodine employed. In operating widi the relative proportions of 

 iodine and acid which I have mentioned, I have no doubt that 

 a farther addition of iodine might be made to the liquid, after 



