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274 THE OPERA rION OE ETLLTNG CAVITIES.
Crystal Mat Gold.—This is anotlior form of crystal J2:<'l diifcrs from that previously (l('S(;ril)<'(l in that it presents a more eomj)act
form, the crystals a})pearing smaller and matted to and crumbles under the instrument to a greater defrree than the other,
and possesses no desirable qualities which the otlua* has not. If it has
any merit it is for tinishing the fillings upon occlusal surfaces, or such
surfaces as are easy of access, or it may be used in conjunction with
amalgam.
Gold and Platinum.—This form of gold has found much favor
with many practitioners for the restoration of incisal edges, or where
for any reason great hardness of surface is desired.
"
An ingot or bar of pure gold and one of platinum are " sweated
together and then rolled to the desired thinness, usually about that of
No. 20 or No. JiO foil. It is then cut into narrow strips, freshly an-
nealed and used after the same manner as heavy foil. The commingling
of the platinum with the gold gives the filling a tint more nearly the
shade of the tooth, and for this reason it is much used upon labial sur-
faces and in mouths where the teeth are much exposed.
Gold thus combined with platinum is much more rigid than gold
alone, and is contraindicated for making the bulk of most fillings. The
best results arc obtained from it when the mallet is used for its con-
densation throughout.
Annealing Gold.
After the manufacturer has reduced the gold to the desired thinness
by beating, his last act before booking it is to heat it ; this is termed
annealing. The object of this is to remove any harshness which has
been given to it by the process of beating. All metals become more or
less stiff or rigid by hammering, but become soft again by the applica-
tion of considerable heat. Gold foil which has been recently made and
excluded from the atmosphere or certain gases, as previously men-
tioned, may present sufficient cohesive properties to weld satisfactorily,
but this property is soon lost, and reheating becomes necessary if it is
desirable to get union of the various layers.
Most operators make use of an alcohol flame for annealing gold
others a small Bunsen gas burner. Some hold the piece of gold to be
annealed in the direct flame or a little above it ; others place the gold
upon a tray of Russia iron, mica, or platinum and hold this in the flame
of the lamp or gas jet. This latter method is safest, since there are apt
to be impurities in the flame dependent upon a charred wick, a particle
of ph(jsphorus dropping into the wick from the burning match, or, in
the case of the gas jet, imperfect combustion which might give either
274 THE OPERA rION OE ETLLTNG CAVITIES.
Crystal Mat Gold.—This is anotlior form of crystal J2:<'l
form, the crystals a})pearing smaller and matted to
and possesses no desirable qualities which the otlua* has not. If it has
any merit it is for tinishing the fillings upon occlusal surfaces, or such
surfaces as are easy of access, or it may be used in conjunction with
amalgam.
Gold and Platinum.—This form of gold has found much favor
with many practitioners for the restoration of incisal edges, or where
for any reason great hardness of surface is desired.
"
An ingot or bar of pure gold and one of platinum are " sweated
together and then rolled to the desired thinness, usually about that of
No. 20 or No. JiO foil. It is then cut into narrow strips, freshly an-
nealed and used after the same manner as heavy foil. The commingling
of the platinum with the gold gives the filling a tint more nearly the
shade of the tooth, and for this reason it is much used upon labial sur-
faces and in mouths where the teeth are much exposed.
Gold thus combined with platinum is much more rigid than gold
alone, and is contraindicated for making the bulk of most fillings. The
best results arc obtained from it when the mallet is used for its con-
densation throughout.
Annealing Gold.
After the manufacturer has reduced the gold to the desired thinness
by beating, his last act before booking it is to heat it ; this is termed
annealing. The object of this is to remove any harshness which has
been given to it by the process of beating. All metals become more or
less stiff or rigid by hammering, but become soft again by the applica-
tion of considerable heat. Gold foil which has been recently made and
excluded from the atmosphere or certain gases, as previously men-
tioned, may present sufficient cohesive properties to weld satisfactorily,
but this property is soon lost, and reheating becomes necessary if it is
desirable to get union of the various layers.
Most operators make use of an alcohol flame for annealing gold
others a small Bunsen gas burner. Some hold the piece of gold to be
annealed in the direct flame or a little above it ; others place the gold
upon a tray of Russia iron, mica, or platinum and hold this in the flame
of the lamp or gas jet. This latter method is safest, since there are apt
to be impurities in the flame dependent upon a charred wick, a particle
of ph(jsphorus dropping into the wick from the burning match, or, in
the case of the gas jet, imperfect combustion which might give either
