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224
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PRECIOUS STONES.
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Water
is composed of two bodies, which, in the present state of knowledge,
are considered simple: they are two gases—one called oxygen, the other
hydrogen. If a mixture of these two gases is made, and if to this
mixture an ignited body is applied, the two gases combine and form
water; but at the same time there is a production of vivid light, and a
development of a great quantity of heat. These two effects attain their
maximum when the mixture is formed of one volume of oxygen and two of
hydrogen.
If,
instead of forming the mixture immediately, we arrange so that the two
gases arrive separately, in two uniform and continuous streams, at an
orifice of small diameter, and if an ignited body is applied to this
orifice where the gases meet and combine, the mixture takes fire. As
the two gases are constantly renewed at the orifice, the combustion is
not interrupted; and a jet of flame is attained analo-gous to that of a
gas-burner. It gives out little light, but develops an exceedingly
elevated temperature. The contrivance is called the oxyhydro-gen
blowpipe, and is in common use among chemists and others.
By aid of this instrument M. Gaudin melted silica and alumina, and artificially reproduced the corundum.
The corundum, as we have seen, is crystallized
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