Lead \ 219 
White Lead . This may be prepared several ways, 
viz : 
1st, By corroding sheet lead with the fumes of vinegar, 
evaporated by the warmth of a hot bed of dung. This 
is the common process in this country. 
2dly, By using for the same purpose, tanner’s bark 
instead of dung, as the hot-house gardeners of Europe 
now do. 
3dly, By exposing the vinegar pots to the same degree 
of heat excited by burning common fuel. This would 
be a much cleaner way of working ; and in such a coal- 
country as Pittsburgh, I should think it would be full as 
cheap. The common heat of a stove-room, as used in 
England for converting cyder into vinegar, would answer 
very well as I think ; and if not strong enough could easi- 
ly be encreased. 
4thly, By precipitating nitrat or acetat of lead by carbo- 
nated alkali. This makes a very white lead, but it does 
not absorb so much oil, or retain its colour so well, as 
white lead made in a common way. 
Sthly, By decomposing some of the neutral alkaline 
salts, as the muriats of potash and soda. I do not know 
whether the sulphats of potash and soda and the nitrats of 
the same alkalies have been used. Or whether, the mu- 
riats, sulphats, or nitrats of lime and magnesia would an- 
swer the purpose. The principle is the same, but there is 
full room for very important and valuable experiments ; 
which probably will be the subject of a dozen patent rights; 
for in this country, if a man can contrive to eat his green 
peas with a four-pronged fork instead of a broad-pointed 
knife, he applies for a patent to secure the invention. For 
this mode of making white lead, Lord Dundonald has al- 
ready obtained a patent. I greatly doubt whether he was 
entitled to it : for the process is very nearly that of Tur- 
ner’s mineral yellow. 
