228 
ON THE IODIDE OF LEAD. 
ART. XLIX-— COMPARATIVE EXAMINATION OF THE DIF- 
FERENT METHODS OF PREPARING THE IODIDE OF 
LEAD. 
By T. Huraut. 
Several methods of preparing the iodide of lead have 
been described, each of which furnishes tolerably satisfactory- 
results. When executed with care, they yield a pure product; 
and the quantity obtained is not far below what theory re- 
quires. It is consequently indifferent which of these pro- 
cesses is employed when only small quantities of iodide are 
prepared ; but when these are considerable, the differences 
become sufficiently great not to be neglected. There is 
another not less important condition, which ought con- 
stantly to be kept in view with every preparation ; it is the 
obtaining a beautiful product. Now it has long since been 
observed, that the mode of operating and the nature of the 
substances employed in the preparation of the iodide of lead, 
have a very considerable influence on the appearance of the 
iodide. 
Before describing my experiments, I must observe that 
each process has been repeated twice, and each operation 
performed under the same conditions, in order to obtain 
accurate results comparable with one another; I may add, 
that in all cases distilled water was employed ; that the 
purity of the iodine and of the iodide of potassium was pre- 
viously ascertained ; that the nitrate and neutral acetate of 
lead were prepared expressly for these experiments ; and 
lastly, that in each experiment a weight of iodine or of 
iodide was employed which should furnish according to 
theory, 18.20 grms. iodide of lead. 
1. Process by Iodide of Potassium. — This process is the 
oldest employed ; it consists in decomposing the iodide of 
potassium with a salt of lead. The French Codex pre- 
scribes the neutral acetate; but that salt has been generally 
1 ' . .'>V;.' ::':>. ^f^ff*, ■■? ' ' ,■-'■'•*...) 
I 
- 
