204- LEAD. 
it from the sulphur that is combined with it. The next 
process is to mix it with a certain quantity of coke, 
charcoal, or peat, and submit it to the smelting furnace. 
In this furnace there are tap-holes, which, when the 
lead is melted, are opened, and the metal, in a fluid 
state, runs into a large iron pan. The dross which 
floats on its surface is now skimmed off; and the metal 
is taken out by ladles, and poured into cast iron moulds, 
with round ends. The lead thus formed, is ready for 
use, and has the name of pig lead. According to their 
size, the pieces that are thus cast have the appellation 
of pigs, and half-pigs. 
Lead is mentioned in the Sacred Writings ; and is 
described by Homer as in common use at the period of 
the Trojan war. The ancients seem to have considered 
it as nearly allied to tin. The Romans employed it to 
sheathe the bottoms of their ships, fastening it to the 
planks and timbers by nails made of bronze. 
When first melted, lead is bright, but it soon tarnishes 
by exposure to the air. It melts at a temperature very 
low in comparison with most other metals ; and when a 
strong heat is applied, it boils and evaporates. 
Lead is much employed in the useful arts. When 
rolled between iron cylinders to a requisite state of 
thinness and uniformity, it is used for the covering of 
houses and churches, notwithstanding the danger, in 
case of fire, to persons within, who are exposed to a 
shower of burning metal. It is cast into pipes, cisterns, 
and reservoirs for water, as well as into large boilers 
for chemical purposes. But all culinary or domestic 
vessels made of lead, particularly if intended for the 
keeping of acid liquors, should carefully be avoided, as 
the surface of the lead is thereby corroded, and the 
liquid contained in them is rendered poisonous. Hence 
arises that dreadful complaint, too well known where 
cyder is kept in leaden cisterns, called the Devonshire 
colic; hence also the injury which sometimes follows 
from the use of lead in the glazing of coarse earthen- 
ware. 
