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FILLING TEETH 1 1 5
Silver gives strength, expands, and discolours
tin contracts. Gold has been used to decrease con-
traction, and improve strength and colour ; copper
to decrease shrinkage, or control the expansion of
other metals, and add to their tooth-saving properties.
Zinc expands and improves colour. All these
different metals possess different properties when
melted up together, reduced to filings, and mixed
with mercury. The desire has always been to use
them in such proportion that what may be called a
perfectly balanced alloy that will give a perfectly
balanced amalgam will result. The one great and
final test is the behaviour of the amalgam when
placed in teeth in the mouth. After many years'
experiment Dr. Flagg has finally come to the con-
clusion that gold is valueless as a constituent of an
amalgam alloy. He also says that copper, as copper,
and zinc, as zinc, are diametrically opposed to one
another, and for this reason he has never made
such a combination. For many years the Contour
amalgam alloy made by Dr. Flagg consisted of
silver, tin, and gold. His Submarine alloy was com-
posed of silver, tin, and copper. In the Dental
Cosmos, February 1900, he states that a very
gradual increase of copper now gives the formula
of Submarine as silver 60, tin 33, copper 7 ; and the
formula of the Contour alloy is there given as from
FILLING TEETH 1 1 5
Silver gives strength, expands, and discolours
tin contracts. Gold has been used to decrease con-
traction, and improve strength and colour ; copper
to decrease shrinkage, or control the expansion of
other metals, and add to their tooth-saving properties.
Zinc expands and improves colour. All these
different metals possess different properties when
melted up together, reduced to filings, and mixed
with mercury. The desire has always been to use
them in such proportion that what may be called a
perfectly balanced alloy that will give a perfectly
balanced amalgam will result. The one great and
final test is the behaviour of the amalgam when
placed in teeth in the mouth. After many years'
experiment Dr. Flagg has finally come to the con-
clusion that gold is valueless as a constituent of an
amalgam alloy. He also says that copper, as copper,
and zinc, as zinc, are diametrically opposed to one
another, and for this reason he has never made
such a combination. For many years the Contour
amalgam alloy made by Dr. Flagg consisted of
silver, tin, and gold. His Submarine alloy was com-
posed of silver, tin, and copper. In the Dental
Cosmos, February 1900, he states that a very
gradual increase of copper now gives the formula
of Submarine as silver 60, tin 33, copper 7 ; and the
formula of the Contour alloy is there given as from
