312 Chittenden and W hitehouse— Metallic 
(b) Lead Compounds. 
Lieberktihn* states that the lead salt of albumin cannot be obtained 
pure; that the insoluable precipitate formed by the addition of either 
lead nitrate or basic lead acetate to a solution of albumin, is simply a 
mixture. With basic lead acetate, Lieberkiihn obtained a precipitate 
containing 17°86 per cent. of lead oxide, while the precipitate formed 
with lead nitrate contained 12°78 per cent. of lead oxide. 
With protein, Muldert obtained precipitates on the addition of 
neutral lead acetate and lead nitrate, which contained respectively 
12°45 and 12.68 per cent. of lead oxide, while basic lead acetate gave 
a precipitate containing 30°63 per cent. of lead oxide. Berzelius{ 
states that neutral lead acetate precipitates both albumin and blood 
serum, but that the greater portion of the albumin remains dissolved 
in the fluid united with acetic acid. Basic lead acetate on the other 
hand precipitates the albumin completely. 
These last statements accord with our own results; with a neutral 
lead salt only a small precipitate was obtained, the compound being 
soluble apparently in both excess of the lead salt and of albumin, 
while with basic lead acetate the albumin seemed completely precipi- 
tated. 
Further, Berzelius|| states, on the authority of Mulder, that if a 
solution of potassium albuminate be made as neutral as possible with 
acetic acid and then precipitated with lead nitrate, the lead albu- 
minate so obtained contains on thorough drying 5°84 per cent. of 
lead oxide. 
Following are some of the results of our analyses. The compounds 
were made from thoroughly dialyzed albumin and were washed free 
from both lead and any excess of albumin. The preparations were 
dried at 110° C. until of constant weight and the lead was deter- 
mined first by simple ignition, with addition of a little ammonium 
nitrate. The lead oxide, after being weighed, was then dissolved in 
dilute nitric acid, the solution evaporated to a small volume, the lead 
precipitated with a little sulphuric acid, two volumes of alcohol added, 
and the lead sulphate finally filtered and washed with 95 per cent. 
alcohol. The sulphate was then ignited with proper precautions and 
from the weight obtained, the percentage of lead again calculated. 
* Poggendorfi's Annalen,. Band lxxxvi, p. 124. 
} Lehrbuch der Chemie, Berzelius, ix, p. 29.  $ Lehrbuch der Chemie, ix, p. 43. 
|| Lehrbuch, ix, p. 49. 
