Chemistry and Physics. 255 
upon the fat of fowls, geese, snakes, badgers, hares, and particularly 
that of man, show that small portions of these acids, principally the 
caprylic, caproic, and valerianic, are always present. 
caprylic acid, when much diluted with air, resembles closely that of the 
health 
quantity is stated to be about 14 cub. in. per pound. 
At Poullaouen, where the experiments were made, about 20,000 Ibs. 
of argentiferous lead are operated upon ata time. The abstricks or black 
litharge, containing sulphur, are drawn off first. At the end of sixteen 
to twenty hours they are succeeded by the marketable litharge. The 
pure article is received in a conical iron pot of thirty quarts capacity. It 
immediately solidifies at the surface and becomes yellow or greenish 
yellow in color. ter a time the mass cracks in every direction, 
metimes with a sort of explosion, and becomes a friable, crystalline, 
reddish litharge, which, after preparation, is sold. e yellow crust _ 
retaining its color and cohesion, is set aside and revived. _ If the vessels 
are too small the whole mass retains the yellow color and does not ex- 
foliate. The red litharge did not give off oxygen by heating, and yet 
when suddenly cooled assumed the yellow form. Operated upon by 
nitric acid, no peroxyd was formed, showing the absence of minium. 
This is another case of dimorphism, resembling that of sugar, arsenious 
acid, iodid of mercury, &c. G. C. ScHaEFFER. 
3. On the Estimation of Silver, by Gay Lussac’s Process, when Mer- 
cury is present; by M. A. Levon, (Ann. de Chim. et de Phys., Apr. 
1846.)—The assay of silver by Gay Lussac’s method has become uni- 
ersal. One single exception to the perfection of the process has re- 
mained, viz., the presence of mercury, and this is not of common oc- 
currence. . Levol has conquered this difficulty by the following 
ess :— 
The assay, as usual, is dissolved in 5 cub. centimeters of nitric acid 
of 32° Baumé ; ‘it is then supersaturated with 25 cub. cent. of caustic 
Gay Lussac (Ann. de Chim. et de Phys., June, 1846) has verified 
the accuracy of Levol’s process, and proposed to shorten it by adding 
monia. Acetate of soda answers 
equally well. ‘The nitric acid should be completely saturated by the 
soda of the acetate. G. C.8. 
4. A new Method of estimating Lead ; by M. FLoREs DomonrTE, 
(Comptes Rendus, May, 1846.)—This is similar to that of Pe- 
louze for copper. The lead is thrown ian and redissolved by caustic 
