390 IODINE. 



like chlorine, by hydrate of lime or alkaline solutions, to form a 

 class of bleaching salts. Such compounds are wanting in the 

 series of oxides of iodine, which is at present limited to iodic 

 and hyperiodic acids. Sementini imagined that he had formed 

 inferior oxides of iodine, but he is evidently mistaken. The 

 iodate of soda combines with iodide of sodium in several pro- 

 portions, one of which was supposed by Mitscherlich, when he 

 discovered it, to be an iodate of soda, but that this is a double 

 salt of the constitution first mentioned is now beyond 

 doubt. 



A few grains of iodic acid may easily be prepared by the 

 method of Mr. Connel, which consists in heating the most con- 

 centrated nitric acid upon a little iodine, in a wide glass tube, 

 and afterwards evaporating to dryness by a heat not exceeding 

 4 or 500 5 a white crystalline powder remains in the tube, 

 which is anhydrous iodic acid. When a larger quantity is re- 

 quired, the most convenient process is to form, in the first place, 

 an iodate of soda. An ounce or two of iodine may be suspended 

 in a pound of water, with occasional agitation, and a stream of 

 chlorine be passed through, till the whole iodine is dissolved. 

 Carbonate of soda is added to the liquor, which is of a brown 

 colour and strongly acid, till it becomes slightly alkaline, when 

 a large precipitation of iodine occurs, which may be separated 

 and collected on a filter. This iodine may be suspended in 

 water and exposed to a stream of chlorine as before. But the 

 filtered solution contains iodate of soda and chloride of sodium, 

 with a trace of carbonate, which may be neutralized by hydrochlo- 

 ric acid. On afterwards adding chloride of barium to the filtered 

 solution, so long as a precipitate is produced, the whole iodic 

 acid will be thrown down as iodate of barytes, which may be 

 collected on a filter and dried. This iodate is anhydrous, and 

 may be decomposed completely, by boiling 9 parts of it for half 

 an hour with 2 parts of oil of vitriol, diluted with 10 or 12 parts 

 of water. The liberated iodic acid dissolves, and being separated 

 from the sulphate of barytes by filtration, is obtained as an 

 anhydrous crystalline mass when evaporated to dryness by a 

 gentle heat. 



Iodic acid crystallizes from a strong solution, as a hydrate, in 

 large and transparent crystals, which are six-sided tables. This 

 acid is not sublimed, but decomposed, by a high temperature, 

 and leaves no solid residue. Iodic acid is very soluble ; and 



