CHAPTER II. 
—EEEEE 
LEAD AND ZINC AND THEIR NATURAL COMPOUNDS. 
Lead. 
METALLIC LEAD. 
Leap is blue-gray in color; it has a hardness of 1.5, which 
means that it is very soft—so soft that it can be cut easily 
with a knife and scratched with the finger-nail. It is very 
heavy, having a specific gravity of 11.554 to 11.363. It is 
easily malleable and can be pounded into thin sheets, but not 
nearly so thin as gold, silver and some other metals. It is 
easily ductile, but not to a high degree, and, therefore, can- 
not be drawn into a very fine wire. It fuses at 384 deg. C. 
or 633 deg. F., and volatilizes rapidly at a red heat. When 
exposed to the air fresh surfaces tarnish rapidly, particularly 
in a damp air and if the lead has perceptible amounts of im- 
purities. 
Lead is never pure, unless specially refined, as all its natu- 
ral compounds are more or lessimpure. The common im- 
purities are silver, antimony, bismuth, copper, iron, nickel, 
arsenic, with occasional traces of others. JFurther, smelting 
processes are rarely perfect, and generally leave traces of 
sulphur and oxygen in the lead. 
Lead is used for many purposes, the most common of 
which are given in the scheme printed at top of page 35. 
Of these uses the pigments consume fully half of all the 
lead produced, white lead alone consuming more than any 
other one use. Red lead, lead oxide, is used to a great ex- 
tent, but the cheaper red paint composed of the red oxide of 
iron relatively is increasing in use. The other pigments 
have an extensive use for fancy colors, but relatively are of 
little importance. 
In the metallic form, lead is used most extensively at 
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