Page:Popular Science Monthly Volume 90.djvu/894

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�Interior of a naphthalene subliming house. The vapor passes into this chamber and crystallizes on the ceiling and in the air

At the right are shown tanks in which crude naphthalene crystallizes out of light oil. After several days, the oil is drained off

and child in the United States were to use a pint of last year's benzene for cleaning purposes, there would still be left enough to furnish each inhabitant of the District of Columbia with another pint. This enor- mous increase has been more than offset by the simultaneous increase in the demand for explosives.

Ancient signs and wonders pale when we consider the stupendous importance of coal tar. The indigo annually consumed in the United States would buy army rifles for 62,500 United States troops. The sulphur black used in one year weighs as much as two ordinary passenger trains of ten cars each, including the locomotives. The tech- nical name for sulphur black is di-nitro- oxy-di-phenyl-amine. Think of the millions of pairs of ordinary black socks dyed that color!

More than twice as much naphthalene is being used as before the war. It has largely taken the place of camphor. At present it is being used, not so much for exterminating moths, as for killing men,

��since this important coal tar "intermediate" is employed largely in the manufacture of explosives. In 1916, 3,500 tons were pro- duced in the United States.

It is estimated that in 191 7 over 300,000,- 000 gallons of tar, or 3,000,000,000 pounds will be used. Of this, 1,800,000,000 pounds will become pitch, leaving 1,200,000,000 pounds for dyes, medicines, disinfectants, explosives and other similar products.

Before the war, aniline oil, which is de- rived from benzol, and which is so impor- tant in making aniline colors, was not manufactured to any extent in the United States. It was furnished almost exclusively by Germany and England, the prices and conditions being beyond our control. In 1914, imports dropped suddenly. The de- mand for aniline oil became acute. Even yet this precious chemical is not turned out

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