4^8 Sir H. Davy's further Experiments 
phenomena as they are produced by the triple compound of 
potassium, as this substance is most easily procured in consi- 
derable quantities, but as far as I have been able to observe, 
the phenomena presented by the compound of sodium are 
precisely analogous. 
The triple compound of potassium purified by alcohol is 
almost tasteless, has no action on vegetable colours, is very 
little soluble in cold water, but more soluble in hot water; when 
it is thrown into concentrated nitric, or sulphuric, or phos- 
phoric acids, it has no violent action on them. By heat it may 
be dissolved in them, and the solutions, when saturated, congeal 
and form crystalline substances intensely acid. When the 
substance formed by the triple compound and the nitric acid 
is strongly heated, the nitric acid flies off, and at the tempe- 
rature at which it is entirely expelled, the substance itself 
begins to decompose and affords a little iodine and much 
oxygene. 
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 oxygene and iodine, and leaves acid sulphate 
and phosphate of potassa. If when the mixture is rendered 
fluid by heat, a little sugar or other combustible matter is 
added, there is a violent action, and iodine is disengaged with 
great rapidity. 
The triple compound dissolves without decomposition in 
solution of phosphorous acid ; but on heating the solution, 
oxygene is attracted by it, iodine appears, and phosphate of 
potassa is formed. 
When the triple compound is thrown into concentrated 
