358 Further Experiments and Olservations on Iodine. 



The triple compounds from lime and magnesia were solublas 

 without Eitbrding iodine in sulphuric acid ; but on evaporatinj; 

 the acid, at the time that the ve.'isel of platinum in which the 

 experiment was made became dry and ahuost red hot, the violet 

 vapour was perceived. Even the triple compound from baryta 

 did not afford iodine or oxygen by treatment with sulphuric acid, 

 except under the same circumstances. 



3. When I iirst discovered that the triple compounds dissolved 

 in acids without effervescence, I thought it probable that the 

 effect depended upon the formation of a compound of oxygen 

 and iodine, similar to euchlorine, or the oxv-chloric acid, and 

 which remained dissolved in the fluid ; and on this idea I made 

 a number of experiments with the hope of obtaining such a com- 

 bination in a detached form. 



I distilled the solution of the triple compound of potassium ill 

 sulphuric acid, but tlie only gaseous product I obtained was oxy- 

 gen. Sulphuric acid and iodine condensed in the cool part of 

 the apparatus, and the residuum v,-as acid sulphate of potassa. 



Conceiving that a compound of oxygen and iodine might ne- 

 vertheless exi?t in the fluid, and be decomposable at a high tem-» 

 perature, I attempted to obtain it by acting on the triple com- 

 pound of barium by sulphuric acid, and by evaporating the fluid 

 obtained at a gentle heat, and suffering it to cool at different 

 periods of the process ; but in this manner of operating I gained 

 no better results. 



The triple compound of barium is scarcely soluble in water. 

 Wa*er that had been ijoiled upon it gave only a slight cloudiness 

 to sulpluiric acid, which possibly might be owing to some double 

 compound mixed with it : the fluid when evaporated nearly to 

 dryness afforded fumes which had the characters of those of sulr 

 phuric acid, and by a red heat yielded iodine, and left sulphate 

 of baryta. 



When the solid triple compound of baryta was heated in very 

 small quantities of diluted sulphuric acid, the fluid separated ex- 

 hibited acid properties, and when gradually evaporated left a 

 substance which congealed bv coohng, and formed a solid of a 

 yellow colour deliquescent in the air, strongly acid, and which 

 reddened vegetable blues, and did not afterwards destroy them. 

 When strongly heated, the substance afforded the same results 

 as the substance procured from the fluid just mentioned. 



The residual solid matter obtained by the action of sulphuric 

 acid en the triple compound of barium was treated a second 

 time with su!]ihuric acid, yet notwithstanding, when heated to 

 redness, it yielded iodine in abundance. 



I have repeated these experiments very often, because M. Guy 

 Lussac has slated that an acid compound of oxygen and iodine 



may 



