ANNALS 



OF 



PHILOSOPHY. 



JUNE, 1815. 



Article I. 



« 

 A Memoir on Iodine. By M. Gay-Lussac. 



(Continued from p. 302.) 



Hydriodate of Zinc. 



1 HIS salt is easily obtained by putting iode into water with an 

 excess of zinc, and favouring their action by heat, as 1 have aheady 

 explained. I have frequently attempted, but always without success, 

 to make this salt crystallize, because it is extremely deliquescent. 

 Heat first deprives it of its water, tlien melts it, and sublimes it in 

 fine prismatic crystals, similar to those obtained when antimony is 

 oxidized. It is not decomposed by this operation, if performed in 

 close vessels ; but if air be admitted, iodine is disengaged, and 

 oxide of zinc remains. Wlien this hydriodate is dried, it does not 

 differ from ioduret of zinc. 



By taking the mean of three experiments, differing very little 

 from each other, 1 find that ioduret of zinc is composed of 



Iodine .. .' 100 



Zinc 26-225 



Consequently the hydriodate is composed of 



Acid 100 



Oxide of zinc 32-352 



When a solution of hydriodate of |)otash or soda is mixed with a 

 ■olution of metallic oxides, no precipitate is obtained with those of 

 manganese, nickel, and cobalt, which proves that the hydriodatcs 

 of these metals arc soluble. Perhaps we may say that all the cora- 



VoL. V. IC« VI. li C 



