tin and gold.

For filling by hand pressure, use instruments with square ends and
sides, medium serrations, and of any form or size which will best reach
the cavity.

For filling with the hand mallet, use instruments with medium
serrations, and a steady medium blow with a four-ounce mallet; in force
of blow we are guided by thickness of tin, size of plugger, and depth of
serrations, strength of cavity-walls and margins, the same as in using
gold. The majority of medium serrated hand mallet pluggers will work
well on No. 10 tin of one, two, or three thicknesses. If the tin shows
any tendency to slide, use a more deeply serrated plugger. The
electro-magnetic, and mechanical (engine) mallet do not seem to work tin
as well as the hand mallet or hand force, as the tendency of such
numerous and rapid blows is to chop up the tin and prevent the making of
a solid mass, and also injure the receiving surface of the filling. In
using any kind of force, _always_ aim to carry the material to place
before delivering the pressure, or blow.

In order to obtain the best results, there must be absolute dryness, and
care must be exercised, not thinking that because it is _tin_ it will be
all right. Skill is required to make good tin fillings, as well as when
making good gold fillings. Always use tapes narrower than the orifice of
the cavity; they are preferable to rolls or ropes. After a few trials it
is thought that every one will have the same opinion. A roll or rope
necessarily contains a large number of spaces, wrinkles, or
irregularities, which must be obliterated by using force in order to
produce a solid filling; thus more force is employed, and more time
occupied in condensing a rope, than a flat tape; the individual blow in
one case may not be heavier than in the other, but the rope has to be
struck more blows. The idea that a rope could be fed into a cavity with
a plugger faster and easier than a tape has long ago been disproved.
Many of the old-fashioned non-cohesive gold foil operators used flat
tapes, as did also Dr. Varney, one of the kings of modern cohesive gold
operators.

The tape is made by folding any portion of a sheet of foil upon itself
until a certain width and thickness is obtained. This tape is very
desirable in small or proximal cavities where a roll or rope would catch
on the margin and partially conceal the view.

In the form of a tape, perhaps more foil can be put in a cavity, and
there may be more uni