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CELLULOID AS A DENTAL BASE. 67 ;

with thin, well-mixed plaster. Place on the top, wash the
outside of the flask to remove all the surplus plaster, then
place it under gentle pressure for half an hour, or until the
plaster has thoroughly set.
\\'hen ready to separate, place the tiask in hot water for
a few minutes,—the sections may then be readily separated
after this is done remove with a suitable instrument all the
wax that is loose and easily detached, then pour a small
Fig. r,8.

stream of boiling water upon the case until every particle
of wax is washed out. Care should be taken at the same
time not to disturb the tin-foil.
Outlet-grooves or Gates.—There are a number of
methods of cutting vents or gates for surplus material, but
the following, which is about as practiced by Dr. Evans,
is probably the best. The upper half of the flask with piece
invested is shown in Fig. 38. The wax has been washed
out, exposing to view the roots of the teeth, platinum pins,
etc., as ready to receive the base plate; the stippled tin-foil
is clinging to the sides of the plaster, and the reverse