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Lead is an important and costly ingredient of
flint-glass, used as a protoxide, either as litharge or red lead, and
should be perfectly pure, for the presence of any other substance or
metal will be shown in the color of the glass. Consequently, the
purity of the glass depends mainly on the quality of the metallic lead
and its being well manufactured.
The writer believes he was the first person in
the United States, aided by a director of the New England Glass Company,
to build a lead furnace. This was in 1818. His only guide was a volume
of "Cooper's Emporium of Arts and Sciences," which furnished a plan on
a very limited scale.
The furnace proved successful, and enabled the
Company to continue their manufacture of glass at a period when no
foreign red lead was to be procured. They enlarged their works, until
they have become the most important in the country; while for over
thirty years they monopolized the business in all its branches, from the
highest qualities of pure Galena and painter's red lead to common pig
lead. In manufacturing metallic lead, its weight is materially increased
by the absorption of oxygen gas. In 1847 the writer made many test
experiments, one as follows: 660 pigs of blue lead, weighing 45,540 pounds,
turned out from the ovens 48,750 pounds of litharge,-- an increase in
weight of 3210 pounds.
The cost of labor was $65.50; fuel, $86.50;
engine power, $17.50; total, $169.50; and the market value of the excess
in weight of the lead was $250, showing a satisfactory profit to the
company for their outlay in this branch of their business. Chemistry
gives the increase in course of manufacture: In protoxide state, 7 per
cent.; in deutoxide state, 11 per cent.; in tritoxide, 15 per cent.
Muriatic acid will detect iron in lead, on
dissolving a small piece of lead in the acid. If colorless, it is good.
Nitric acid will detect if there is cobalt in
the lead, by adding to the acid half the quantity of high-proof alcohol.
If present, the evidence is soon seen.