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USE OF AMALGAM. 317
be so adjusted that they are immovably held during the filling ope-
ration.
A rapid method of forming a matrix is that of Dr. Wilhelm Herbst
A strip of German silver No. 33, wide enough to extend from the
cervical margin of a cavity to its mouth, and long enough to more than
embrace the tooth, is passed around the tooth (see Fig. 275) ; the strip
is caught near its extremities by a pair of Herbst pliers (Figs. 276,
277) and drawn taut; the pliers pinch the metal into close adaptation
to the tooth walls. Held by the pliers the matrix is withdrawn, the
line of junction touched with zinc chlorid solution, and soldered over
an alcohol or Bunsen flame with soft solder. The matrix is replaced
upon the tooth, the rubber dam applied, and the matrix pressed
against the cervical margin of the cavity by means of a wooden
wedge.
The matrices of Guilford and those of Brophy (Figs. 253, 254,
Chapter XII.) are operated upon a common principle ; the band which
most nearly fits the periphery of the tooth is adapted, then drawn
into close apposition with the tooth by means of the screw appli-
ances.
The matrix of Woodward is one of the most convenient. Its mode
of application is shown in Fig, 256, Chapter XII.
The Miller matrix (Fig. 278) is useful and adapted for the class
of cavities shown in Fig. 279, as held in contact with cervical mar-
FiG. 278.
gins through the action of the duplex spring leaflets. Fio. 279.
When necessary a wooden wedge is forced between
the leaflets.
(For other forms and applications of matrices see
Chapter XII.)
Mixing the Amalg-am.—It is usually recom- Miller matrix adjusted.
mended that the proportion of mercury and alloy be determined by
weight. An amount of alloy is first weighed, then weighed additions
of mercury are added to it sufficient to make a plastic mass, when the
two are to be mixed together ; the relative amounts of mercury and
alloy are to be gauged and recorded for eacli formula of alloy. With
the " submarine " alloy of Flagg—60 silver, 35 tin, and 5 copper—the
USE OF AMALGAM. 317
be so adjusted that they are immovably held during the filling ope-
ration.
A rapid method of forming a matrix is that of Dr. Wilhelm Herbst
A strip of German silver No. 33, wide enough to extend from the
cervical margin of a cavity to its mouth, and long enough to more than
embrace the tooth, is passed around the tooth (see Fig. 275) ; the strip
is caught near its extremities by a pair of Herbst pliers (Figs. 276,
277) and drawn taut; the pliers pinch the metal into close adaptation
to the tooth walls. Held by the pliers the matrix is withdrawn, the
line of junction touched with zinc chlorid solution, and soldered over
an alcohol or Bunsen flame with soft solder. The matrix is replaced
upon the tooth, the rubber dam applied, and the matrix pressed
against the cervical margin of the cavity by means of a wooden
wedge.
The matrices of Guilford and those of Brophy (Figs. 253, 254,
Chapter XII.) are operated upon a common principle ; the band which
most nearly fits the periphery of the tooth is adapted, then drawn
into close apposition with the tooth by means of the screw appli-
ances.
The matrix of Woodward is one of the most convenient. Its mode
of application is shown in Fig, 256, Chapter XII.
The Miller matrix (Fig. 278) is useful and adapted for the class
of cavities shown in Fig. 279, as held in contact with cervical mar-
FiG. 278.
gins through the action of the duplex spring leaflets. Fio. 279.
When necessary a wooden wedge is forced between
the leaflets.
(For other forms and applications of matrices see
Chapter XII.)
Mixing the Amalg-am.—It is usually recom- Miller matrix adjusted.
mended that the proportion of mercury and alloy be determined by
weight. An amount of alloy is first weighed, then weighed additions
of mercury are added to it sufficient to make a plastic mass, when the
two are to be mixed together ; the relative amounts of mercury and
alloy are to be gauged and recorded for eacli formula of alloy. With
the " submarine " alloy of Flagg—60 silver, 35 tin, and 5 copper—the
