ON THE PREPARATION OP THE IODIDE OF LEAD. 299 
The experiments made by the author on this subject confirm 
the previous statements. In order to discover whether the 
acetate of potash, which is formed by the double decompo- 
sition, is the cause of the increased solubility of the iodide 
of lead, the author triturated iodide of lead together with 
some acetate of potash. The mixture, after having deli- 
quesced to a syrup from the absorption of moisture, soon 
became perfectly white, and had no reaction upon blue lit- 
mus-paper. After some length of time, silky needles of the 
protiodide of lead and potassium separated; on adding 
water to the mixture, the yellow iodide of lead was precipi- 
tated, and the liquid became acid. This liquid subsequently 
afforded with basic acetate of lead a yellow precipitate, and 
nitric acid and very dilute sulphuric acid likewise threw 
down some yellow iodide of lead. When the white syrupy 
mixture of acetate of potash and iodide of lead was pre- 
viously extracted with alcohol, the white residue deposited, 
on the addition of a weak acid, a yellow protiodide of lead, 
and the filtered liquid gave, on the addition of nitric acid, a 
precipitate of the same compound. When, on the other 
hand, iodide of lead was boiled with an aqueous solution 
of acetate of potash, the author obtained a colourless acid 
liquid, which deposited white silky crystals of the protiodide 
of lead and potassium, while an insoluble yellowish-white 
residue of the oxyiodide of lead was left. Hence it appears 
that wherever acetate of potash and iodide of lead come in 
contact with each other, the precipitate never contains the 
whole of the iodide of lead formed; but, on the contrary, 
there is always a loss due to the protiodide of lead and 
potassium remaining in solution. No such loss occurs on 
precipitating iodide of potassium with nitrate of lead. — 
Chem. Gaz. from Journ. cle Pharm. et de Chim. 
