ON THE IODIDE OF LEAD. 
331 
of iron is rather useful than otherwise, nevertheless! see no 
reason for employing three times more of that metal than is 
required. 
10 grms. of iodine, converted into iodide of iron, and 
treated with neutral acetate of lead, afforded 16.70 to 16.75 
iodide of lead. I obtained a more satisfactory result by 
precipitating the iodide of iron from 10 grms. of iodine with 
a solution of nitrate of lead; the product weighed 17.50 — 
17.50 grms. The iodide of lead obtained from the iodide 
of iron is of an orange color, and dissolves entirely in boil- 
ing water. It possesses the same characters whether the 
acetate or nitrate of lead has been employed. 
5. Process by Iodide of Zinc. — I am not aware that the 
iodide of zinc has been proposed for the preparation of the 
iodide of lead, and nevertheless this salt is the one now 
most frequently employed; its great solubility and the 
readiness with which it is obtained will readily account for 
the preference given to it; it is moreover not altered in the 
air. 10 grms. of iodine, converted into iodide of zinc, fur- 
nished 17.05 to 17.15 grms. iodide of lead on precipitation 
with the neutral acetate, and 17.40 to 17.45 with nitrate of 
lead; the iodide is of a pale orange-yellow color, sometimes 
lemon-colored. 
6. Process by the Double Iodide of Potassium and Lead, 
— In a recent paper on the iodide of lead, M. Thevenot has 
proposed a new process for preparing this salt ; it is founded 
on the decomposing action of water upon the combination 
which the iodide of potassium forms with the iodide of 
lead. This compound is prepared in the following manner. 
Take- 
Iodide, . . 10 parts 
Iodine of potassium, 4 . 10 u 
Distilled water, . . . 5 " 
Divided lead, . a large excess. 
Nitrate of lead, . . . 10 parts. 
The four first, substances are mixed in a beaker, and set 
