ON WHITE LEAD. 
75 
and suffered to fall in showers before the decomposition is 
sufficiently effected. 
There are several points deserving of notice, relative to 
this mode of manufacturing white lead. The quantity of 
litharge obtained in different processes of the arts is greater 
than the commercial demand for it, and as a reconversion of 
it into metallic lead is attended with a loss of more than one- 
sixteenth of its weight, it is desirable to find purposes to which 
it may be directly applied, unattended with loss. These pro- 
cesses for making white lead are of such a character, and 
hence, if the best quality of white lead cannot now be made 
by them, it is worth devoting time to their improvement. 
But, again, there is a much greater nicety in conducting these 
operations over the old methods, and there mcty be introduced 
into them a greater certainty in regard to the amounts of the 
several materials employed, circumstances which certainly 
impart some value to them considered with reference to the 
health and cleanliness of operatives, and to economy to the 
manufacturer. Of all the processes given above I should be 
inclined to prefer that of the fourth patent, as being most 
likely on theoretic grounds to produce the best result. Before 
closing this portion of our subject, we must make reference to 
the manufactory in Brooklyn, New York, the only one in 
this country, as far as my information extends, where The- 
nard's principle is successfully pursued. The sample of 
white lead from this establishment, offered at the exhibition of 
the Franklin Institute last fall, was considered to be about 
equal to the others, and spoke well for the method, if it was 
made on this principle, for I understand they pursue both 
the older and the precipitating processes. 
B. Older processes. — Among these we include the old 
Dutch method, where a fermenting material was employed, 
and that which substitutes a heated chamber for the ferment- 
ing beds. The oldest among these is probably that which 
originated in Holland, where rolled sheet lead is placed in 
earthen pots containing a small quantity of vinegar in the 
bottom, and these pots then buried in dung, which, by its fer- 
