356 Further Experiments and Observations on Iodine. 



The triple compound of pota^siinn purified by alcohol is al- 

 most tasteless, has no action on vep;etable colours, is very little 

 soluble in eokl water, but more soluble in hot water ; when it 

 is thrown into concentrated nitric, or sulphuric, or phosphoric 

 acids, it has no violent action on tliem. By heat it may be dis- 

 solved in them, and the solutions, when saturated, congeal and 

 form crystalline substances intensely acid. V.'hen the substance 

 formed by the triple compound and the nitric acid is strongly 

 heated, the nitric acid flies off, and at the temperature at which 

 it is entirely expelled, the substance itself begins to decompose 

 and affords a little iodine and much oxygen. 



If the solution of the triple compounds in sulphuric or phos- 

 phoric acids be heated strongly at the temperature at which the 

 acids sublime, the triple compound itself is decomposed, and it 

 affords oxj-gen and iodine, and leaves acid sulphate and phos- 

 phate of potassa. If when the mixture is rendered fluid by heat, 

 a little sugar or other combusti])le matter is added, there is a 

 %'iolent action, and iodine is disengaged with great rapidity. 



The triple compound dissolves without decomposition in so- 

 lution of phosphorous acid ; but on heating the solution, oxygen 

 is attracted by it, iodine appears, and phosphate of potassa is 

 formed. 



When the triple compound is thrown into concentrated mu- 

 riatic acid, there is an effervescence, the smell of chlorine is 

 perceived, the fluid becomes yellow, and when evaporated yields 

 the chloTionic acid. 



When the solution of the hydroionlc acid in water is poured 

 upon the triple salt, iodine is instantly produced in great quan- 

 tities. 



Acetic and oxalic acids dissolve the triple compound without 

 decomposing it. On heating the solution in oxalic acid, the 

 acid becomes brown from the deposition of charcoal, and iodine, 

 immediately appears. 



When the triple compound is thrown into solution of suU 

 phurous acid, iodine is instantly produced, and sulphuric acid 

 formed, and if the sulphurous acid is not in too large a propor- 

 tion, the solution becomes yellow bv dissolving by iodine j if 

 more sulphurous acid is added, water is decomposed, and sul- 

 phuric acid, and hydroionic acid fornied. 



The double compound of pctasr.ium and iodine has no action 

 on oxalic, acetic, sulphuious, or jihosphorous acids, but when it 

 is mixed with the triple compound it is instantly decomposed 

 by them, and iodine set free. 



The same double compound in its pure state is decomposed 

 very slowly by muriatic acid ; and to convert the greater por- 

 tion into muriate of potassa (potassane) it is necessary that the 



acid 



