IODIDE or POTASSIUM. 
115 
Iodide of potassium is generally stated to be deliquescent, 
but this is the case only when the air is extremely moist. 
The iodide, as it is found in commerce, is generally in the 
form of opaque cubic crystals of a white colour, which decrepi- 
tate when heated. A solution of the iodide, when allowed to 
evaporate spontaneously, deposits crystals which are perfectly 
transparent and colourless. 
Iodide of potassium consists of one equivalent of iodine 
126.3, and one of potassium 39.15 = 165.45. 
One hundred parts of water, at the temperature of 64°, 
dissolve 143 parts of the iodide.* It is soluble in one-half its 
weight of water at 212°. Alcohol of specific gravity, .835, at 
the temperature of 60°, dissolves about one-eighth its weight; 
in boiling alcohol it is much more soluble. 
Iodide of potassium is decomposed by sulphuric, nitric, and 
hydro-chloric acids; and by the salts of lead and of mercury. 
The only officinal preparation of this iodide is the " Un- 
guentum potassse hydriodatis." of the Dublin Pharmacopoeia. 
* Thenard. 
