ON THE IODIDE OF LEAD. 
229 
abandoned, since Messrs. Depaire and Boudet have shown 
that the iodide of lead dissolves in considerable quantity in 
the acetate of potash which is formed by the double decom- 
position of the iodide of potassium and acetate of lead. 
The loss, according to M. Boudet, is about one-tenth. 
13.10 grms. of iodide of potassium, containing lOgrms. of 
iodine, were treated with neutral acetate of lead, the weight 
of the precipitated iodide was 15.70, to 15.80 grms. To 
avoid the loss to which the use of acetate of lead gives rise, 
M. Boudet proposed to substitute for this salt the nitrate of 
the same base. On treating 13.10 grms. of pure iodide of 
potassium with a solution of nitrate of lead, 17.50 to 17.55 
grms. of iodide were obtained. 
According to M. Thevenot, this loss may be avoided by 
pouring into the liquid above the iodide of lead a little nitric 
acid, which precipitates the greater portion of the iodide of 
lead held in solution. I tried this plan, and obtained with 
the same proportions 17.30 grms. iodide of lead. On the 
other hand, I treated the wash-waters from the first expe- 
riment with a sufficient quantity of nitric acid to decom- 
pose the acetate of potash they contained, and I collected 
1.45 grm. of iodide of lead in brilliant scales. 
The iodide of lead prepared with iodide of potassium is 
of a beautiful lemon-yellow color, and entirely soluble in 
boiling water. Sometimes it. is obtained in the form of 
minute brilliant laminae, at other times without any crystal- 
line form. This effect, which occurs in all the methods of 
preparing the iodide of lead, appears to me to be attribut- 
able to the more or less concentrated state of the liquors. 
2. Process by Iodide of Sodium.— Wrthexio the iodide of 
sodium has never been employed, as far as I am aware, 
owing to its liability to change by exposure to the air and 
heat. However, as it may be obtained in a pure state in 
the liquid form, I was curious to know the results it would 
yield, and converted 10 grms. of iodine into iodide of sodium, 
which furnished with acetate of lead 15.90 to 16.10 of 
20 
