Chemical Science. 411 



in a warrii air-stove. Crystals were formed, being hexagonal 

 plates ; when separated from the fluid they retained a little hydro- 

 fluoric acid, but merely warming them on paper caused the dissipa- 

 tion of the latter. In these experiments the funnels and capsules 

 were of course covered with wax to prevent the action of the hydro- 

 fluoric acid. 



A solution of iodic acid mixed with sulphuric acid, and eva- 

 porated spontaneously in a stove, gave the former acid in crystals. 

 Thick syrupy iodic acid, in a dry place, also gradually crystallized. 



A solution of iodate of soda, mixed with at least twice the quan- 

 tity of sulphuric acid necessary to saturate the ijoda present, being 

 boiled for 12 or 15 minutes, is to be filtered and concentrated; the 

 liquid, left in a stove at 68° or 77° F., in a short time yields a crys- 

 talline mass, from which the crystals are to be separated, and 

 washed with a very little water; being then placed on filtering paper, 

 they are to be allowed to drain and then dried in a warm air-cham- 

 ber. When pressed they divide into small brilliant crystals. The 

 mother-liquor contains sulphuric acid, sulphate of soda, and a little 

 iodic acid. This crystallized acid is usually quite pure, and when 

 heated leaves no residue. If a little sulphate of ioda be present, the 

 acid should be recrystallized from sulphuric acid. 



This experiment is important, as it shews that iodate of soda 

 may be made to yield iodic acid, by the simple action of sulphuric 

 acid ; and it also led to the observation, that the compounds of iodic, 

 with other acids mentioned by Davy, had no real existence. The 

 precipitates he obtained were in fact iodic acid crystallized, and 

 moistened with the acid used in each experiment. 

 ' Crystallized iodic acid is not sensibly altered by exposure to air, 

 and does not appear to be deliquescent. It has a particular odour, 

 partly that of iodine. It is very soluble in water, and but very 

 slightly in alcohol ; the latter substance precipitates the aqueous 

 solution. It does not, as some have said, act upon gold. — Amiales 

 de Chiinie, xliii. 216. 



2. On Chloride of Iodine. Serullas. — A solution of chloride of 

 iodine in water, even when dilute, may be precipitated by sulphuric 

 acid, if it be added in successive portions, until in sufficient quan- 

 tity, the vessels being at the same time cooled. The chloride ap- 

 pears as a caseous white matter, which, as it acquires consistence, 

 assumes the orange yellow colour of the perchloride. If the preci- 

 pitate be heated in the liquid, it is dissolved, but appears again upon 

 cooling. When the mixture is distilled, the perchloride volatilizes 

 and condenses in the neck of the retort. 



It is still a question whether chloride of iodine when put into 

 water, remains unaltered, or becomes muriatic and iodic acids. As 

 these acids mutually decompose each other, the former appears to 

 be the most probable opinion. When the muriatic and iodic acid are 

 mixed, and then sulphuric acid added to the solution, chloride of 

 iodine is separated. The colour also produced upon mixing the 



