That it is not used in all the glass houses of Pittsburg
is due to the fact that its advantages were not fully known when the
furnaces were fired last summer, and it costs a large sum to permit the
furnaces to cool off after being heated for melting. When the fires cool
down, and before they are started up again, the furnaces now using
coal will doubtless all be changed so as to admit natural gas. The
superiority of French over American glass is said to be due to the fact
that the French use wood and the Americans coal in their furnaces, wood
being free from sulphur, phosphorus, etc. The substitution of gas for
coal, while not increasing the cost, improves the quality of American
glass, making it as nearly perfect as possible.
While the gas is not used as yet in any smelting furnace nor in the
Bessemer converters, it is preferred in open hearth and crucible steel
furnaces, and is said to be vastly superior to coal for puddling. The
charge of a puddling furnace, consisting of 500 pounds of pig-metal and
eighty pounds of "fix," produces with coal fuel 490 to 500 pounds of
iron. With gas for fuel, it is claimed that the same charge will yield
520 to 530 pounds of iron.
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