530 
ON THE IODIDE OF LEAD. 
iodide, and with the nitrate 16. S5 to 16.95. This iodide is 
perfectly similar to that obtained with the iodide of potas- 
sium, and is of a lemon color. 
3. Process by Iodide of Calcium. — All the soluble iodides 
may be used for the preparation of iodide of lead, but not 
with the same advantage. Thus those, the preparation of 
which is attended with much difficulty or requires long 
time, are not used, whilst those which are readily and 
quickly prepared are employed indifferently. Till of lnte 
the iodide of calcium has not received any application; but 
a few months ago M. Criquellon having described a very 
simple and cheap method of obtaining it, this iodide may 
now be turned to account. To see whether it offered any 
advantage in the preparation of the iodide of lead, I decom- 
posed a solution containing 10 grms. of iodine by a solution 
of nitrate of lead, and obtained 17.70 to 17.60 grms. of a 
beautiful orange-yellow iodide of lead. The second expe- 
riment, made so as to give a crystalline iodide, furnished a 
product of remarkable brilliancy. 
I then treated a similar solution of iodide of calcium with 
acetate of lead ; the weight of the precipitate was 17.25 to 
17.40. This iodide was likewise of a beautiful orange- 
yellow color. 
4. Process by Iodide of Iron. — In a memoir presented to 
the Ecole de Pharmacie of Paris, in 1S40, M. Girault 
showed that the iodide of iron might be employed with 
advantage for the preparation of the iodide of lead; he 
pointed out the inconveniences which attend the use of this 
compound, and made known the precautions which should 
be taken to avoid them. Subsequently, in 1847, M. Gaf- 
fard, without being acquainted with the researches of M. 
Girault, likewise proposed the iodide of iron for the prepa- 
ration of the iodide of lead ; the prescription, however, which 
lie has given has been justly criticised by M. Thevenot. 
But even in the corrected formula, the latter chemist has 
retained too large a proportion of iron. Although an excess 
