214 On Iodine. [March, 



saturate the wliole of the barytes in the iodate, a small portion of it 

 always remains mixed with the iodic acid. If we endeavour to 

 separate this portion by adding barytes- water, the two acids preci- 

 pitate together. I suppose that the presence of a small quantity of 

 sulphuric acid in the iodic acid depends upon the strong affinity of 

 this last acid for barytes. I do not think there is reason to believe 

 that the two acids have a tendency to combine together, in conse- 

 quence of which the iodate is decomposed. 



The iodate of lime and sulphuric acid give similar results. 

 When tlie same salt and oxalic acid are used, the decomposition 

 seems to be more complete. 



Hitherto iodic acid has only been obtained in combination with 

 water, and it is very probable that this liquid is as necessary as a 

 base to keep the elements of the acid united, as we see is the case 

 with sulphuric acid, nitric acid, &c.* Its taste is very acid when 

 it is concentrated. Light does not decompose it. It may be 

 evaporated to the consistence of a syrup. But if its temperature be 

 raised to about 392°, it is decomposed entirely into iodine and 

 oxygen. Sulphurous and hydro-sulphuric acids immediately sepa- 

 rate iodine from it. This acid and hydriodic acid are decomposed 

 almost completely, like sulphurous and hydro-sulphuric acids. If 

 we mix it with concentrated hydro-chloric acid, chlorine is dis- 

 engaged. Sulphuric and nitric acids have no action on it. With 

 solution of silver it gives a white precipitate, very soluble in 

 ammonia. It combines with all the bases, and produces all the 

 iodates which we obtain by making the alkaline bases act upon 

 iodine in water. It likewise forms with ammonia a salt, which 

 fulminates when heated, the existence of which I announced some 



time ago. 



From experiments which I shall state in speaking of the iodates, 

 this acid is composed of 



Iodine ] 00 



Oxygen 31-927 



Now the first possible combination of iodine and oxygen being 



Iodine ] 00 



Oxygen 6-4017 



Iodic acid is evidently a compound of 



Iodine ] 00 



Oxygen 6-4017 x 5 = 32*0085 



That is to say, that iodic acid contains five proportions of oxygen. 



* The existence of acids without water shows a grcriter reciprocal affinity in 

 their elemeuts than in those acids -which exist only by means of water or a base, 



{To be continued.) 



