r 
-«i;si. 
LEAD. 
dissolved in nitric acid by means of heat, 
except a few particles of iron, which remain 
at the bottom. By the addition of sulphu- 
ric acid, the lead is thrown down in the 
form of white flakes of sulphate; which, 
when washed and dried, discover the quan- 
tity of lead they contain, by the same al- 
lowance of 143 grains of the salt to 100 
grains of metallic lead. The remaining 
solution being evaporated to dryness, af- 
fords phosphoric acid. Lead is abundantly 
found in combination with sulphur, in the 
form of heavy, shining, black, or bluish, 
lead-coloured cubical ma.sses, whose corners 
are usually truncated its texture is lami- 
nated, and its hardness variable. This is 
called galena, or potter’s lead ore. Most 
lead ores contain more or less of silver. 
When antimony enters into its composition, 
the texture is radiated or filamentous. 
There are also lead pyrites, which contain a 
considerable proportion of iron and sul- 
phur ; and red lead spar, which consists of 
lead mineralized by sulphur and arsenic : 
this is very scarce. 
If suIphurettCLl lead be boiled in nitric or 
muriatic acid of a moderate strength, the 
sulphur may be obtained pare, and collect- 
ed on a filter. When iron or stony particles 
are contained among the undissolved part, 
the sulphur may be separated by digestion 
in a solution of pure fixed alkali, which con- 
verts it into sulphuret, and leaves the other 
insoluble matters behind. If the first solu- 
tion be made with nitric acid, it may con- 
tain silver and lead, which after precipita- 
tion by carbonate of soda, may be separated 
by ammonia, as mentioned in the humid 
analysis of the calciform ores; when the 
muriatic acid is used for the solution of the 
ore, a large quantity of muriate of lead se- 
parates, for want of a sufficient quantity of 
water to dissolve it. This requisite quan- 
tity of water must be added to dissolve the 
salt, before the precipitate is made by the 
fixed alkali. 
All the ores of lead, except the phospho- 
ric, are reducible to the metallic state by 
dissipating their volatile contents by the 
blow pipe on a piece of charcoal. In the 
large way, they are reduced by fusion with 
charcoal. 
The ores of this metal are abundantly 
found in the mine counties of England, and 
in various other parts of the globe. Its uses 
are numerous, and scarcely need be men- 
tioned. Its oxides are of great use as a 
pigment, and in the manufacture of glass. 
Lead is cast into thin sheets for covering 
buildings, making water-pipes, and variouf 
other uses ; and tliis is rolled between two 
cylinders of iron, to give it the requisite 
uniformity and thinness. Lead is thought, 
and with some reason, to be not perfectly 
innocent, even for water pipes, and much 
less so for any other kind of vessels. The 
workmen in any of the preparations of lead 
are generally subject to a peculiar colic, 
and paralytic disorders, which most pro- 
bably arise from the internal use of the 
metal ; for it is a fact, that tliese workmen 
are not sufficiently cautious in washing 
their hands, or removing such particles of 
lead, or its preparations, as may casually 
intermix with their food. 
Most of the acids attack lead. The sul- 
phuric acid scarcely acts upon it, unless it 
be concentrated and boiling. Sulphurous 
acid escapes durihg the process, the acid 
being decomposed. When the distillation 
is carried on to diyness, a saline white mass, 
remains, a small portion of which is soluble 
in water, and is the sulphate of lead ; it af- 
fords crystals. The residue of the white 
mass is an oxide of lead. 
Nitric acid acts strongly on lead, and 
converts it into a white oxide if the acid be 
concentrated ; but if it be more diluted, the 
oxide is dissolved, and forms nitrate of lead 
which is crjstallizable, and does not afford 
a precipitate by cooling. It detonates on 
ignited coals. Lime and alkalies decompose 
the nitrous solution of lead. The sulphuric 
acid added to this solution combines with 
the metallic oxide, and falls down. The 
muriatic acid in the same manner carries 
down the lead, and forms a combination 
which is more soluble in water than the mu- 
riate of silver. 
Muriatic acid acts directly, but sparingly, 
on lead by heat, which it oxides, and dis- 
solves in part. The muriate of lead is crys- 
tallizable. 
The acetic acid dissolves lead and its 
oxides ; though the access of air or oxygen 
seems necessary for the solution of the me- 
tal itself in this acid. White lead, or ceruse, 
is made by rolling leaden plates spirally up, 
so as to leave the space of about an inch 
betv^een each coil, and placing them verti- 
cally in earthen pots, at the bottom of which 
is some good vinegar. The pots are to be co- 
vered, and exposed for a length of time to a 
gentle heat in a sand batli, or by bedding 
them in dung. The vapour of the vinegar, as- 
sisted by the tendency of the lead, to combine 
with thf oxygen of the air which is present, 
corrodes the lead, and converts the external 
