28 PREPARATION OF CARBONATE OF LEAD. 
ART. XIX. — THEORY OF THE PREPARATION OF CARBO- 
NATE OF LEAD — CERUSE. 
M. Pelouze has opened new views upon the theory of 
this preparation, which completely explain the facts ob- 
served. 
The process followed in France, for this prepartion consists 
in passing a current of carbonic acid through a solution of 
tribasic acetate of lead, which is thus brought to the 
state of a neutral acetate, with a precipitate of carbonate of 
lead. The carbonate of lead being separated, a new portion 
of litharge is dissolved in the neutral acetate, which is again 
converted into"a triacetate, to be again operated upon as at 
first. This, process, has been modified in England, in the 
following manner. The litharge is mixed with the hundredth 
of its weight of acetate of lead, and this mixture, moistened 
with a very small quantity of water, is subjected to a current 
of carbonic acid. After a few hours the whole of the litharge 
is carbonated and the operation completed. It is evident 
that in this process the acetate of lead acts as in the French 
process — working successively upon every part of the litharge, 
which it changes to sub-acetate of lead — then abandons it 
to the carbonic acid, which transforms it to a carbonate. 
In the Dutch process practised in France, and particularly 
at Lille, for several years past, the lead is placed in the form 
of thin plates, upon small earthen vessels, in which vinegar 
is placed. The whole is then placed in dung and dis- 
posed in such a manner that air may have access to it through 
the mass. 
According to Pelouze, the vinegars employed in this fac- 
tory contained but one thousandth of real acid. This acid, 
volatilized by the heat of the fermenting compost, acting up- 
on the oxide of lead, gives a small quantity of acetate of lead, 
which under the influence of moisture and air, transforms the 
