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I02 MECHANICAL DENTISTRY AND METALLURGY.

This is done Ijy holding the surface of a mirror over the
openings in the flask ; if there is a trace of moisture being
driven ofif it will l)e shown upon the glass, and the heat
should be continued until the case is completely dried, when
it is ready for casting.
Pouring the Metal.—The metal should now be poured
into the mold through one of the lateral openings, and it
should rise quickly and freely into the opposite one. If
bubbling should occur, which will never happen if the cast
has been sufficiently dried, the flask should be lightly tapped
on some hard surface until the ebullition ceases, thus in-
suring a more certain intrusion of the metal into all parts of
the mold before solidification takes place.
The Finishing Process.—When the flask is quite cold.
the plate may be readily removed by soaking the investing
material for a moment in water. All superfluous metal is
now removed with suitable scrapers, files, and sand-paper or
emory cloth, and the final polish given with the brush-
wheels, pumice-stone, and whiting.
When it is desirable to make a pink rubber rim about the
necks of the teeth, this portion of the wax should be
carved out before flasking and pouring the metal. The
wax can be carved away to any depth to suit the require-
ments of the case. The plaster will run in and fill this
space in the flasking process, thus preventing metal from
occupying it. After the metal is finished up, rubber may
be packed al)out the teeth in the usual way and vulcanized.

ARTIFICIAL DENTURES UPON AN
ELECTRO DEPOSITED BASE.
Deposition of Copper by the Single-Cell Process.—The
simplest form of arrangement for the deposition of metals,
either for artificial dentures or electrotyping small objects,