232 
Lead \ 
common salt as I think. By degrees, and by remaining 
together for twelve hours more, the common salt became 
decomposed ; a muriat of lead was formed, and pure 
soda, the basis of the common salt. The pure soda was 
drained first and the remainder washed away, and boiled 
down to chrystailize, in a room where charcoal was burnt 
iiit braziers, to supply carbonic acid gas. The pure soda 
would not decompose the muriat of lead, there being only 
one divellent affinity, viz. that of soda. 
The lead thus freed by washing from the soda, was put 
into crucibles and fused in a strong heat Jit then became 
a yellow clirystallized mass, the patent yellow of the shops. 
The soda when chrystallized, was disposed of as carbo- 
nat of soda. 
Now, if the soda, instead of being washed away, had 
been left quietly to gain from the atmosphere or elsewhere 
its carbonic acid, being still in contact with the white, 
moist, muriat of lead, there would have been two dive!- 
lent affinities, and a double decomposition would have 
taken place : the carbonic acid would unite with the lead, 
while the muriatic acid would again unite with the soda, 
reproducing the original quantity of common salt, which 
might be washed away, re-chrystallized, and used again 
for the same purpose. The carbonated lead thus pro- 
duced would be white lead . 
Lord Dundonald discovered, that although common 
salt and various other alkaline neutrals would answer the 
purpose, the decomposition went on best with muriat of 
potash, instead of muriat of soda. And in this way is the 
greatest proportion of English white lead now made. 
In England, the making of white lead, is connected 
with the manufactory of soap ; almost all the alkali now 
used for soap being procured from the decomposition of 
neutral alkaline salts by means of oxyds of lead* For by 
thus procuring them, the expence of rendering the ley 
