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234 THE TECHNICAIi PBOCEDURES IN FILLING TEETH.

The above may be compared with fillings made of gold foil
uuder different conditions named below.

TABLE SHOWING SPECIEIG GRAVITY OP GOLD FILLINGS, WITH THE PER
CENT OF SHORTENING UNDER A STRESS OF THREE HUNDRED
POUNDS. FILLINGS ONE-TENTH INCH CUBES.

Specific Percent of Shortening
Gravity. under stress of 300 Iba.
No. 1. Gold foil. Heavy mallet used with the inten-
tion to produce maximum density 19.38 0.9
No. 2. Gold foil as in No. 1, except that hammer was
used 19.42 1.0
No. 3. Gold foil No. 4 in jj sheet pieces. Mallet force
as in building fillings exposed to unusual stress.
Slab on table 19.18 1.9
No. 4. Same as No. 3, but filled more rapidly 18.61 3.7
No. 5. Gold foil No. 4 in ^ sheet pieces with mallet
force same as usual in filUng teeth. Slab on
cushion 17.4 6.4
No. 6. Two half sheet cylinders of No. 4 foil, non-
cohesive, placed in the bottom of the cavity, filling
it nearly full. Cohesive foil malleted upon them.
Slab on cushion 18.0 39.8
No. 7. Cylinders, J sheet each, non-cohesive foil No. 4,
laid on bottom of cavity and cohesive gold mal-
leted over. Slab on cushion 18.3 7.3
No. 8. Platinum gold—all annealed—^mallet force
ordinary. Slab on cushion 4.8
No. 9. Platinum gold folds used flat. Ordinary mallet
force. Slab on cushion 7.0
No. 10. Platinum gold foil No. 60. Mallet force as in
building fillings much exposed to wear. Size of !!^
point, 5x10 tenths millimeters. Slab on cushion 0.8

The first four fillings in this table are, of course, purely
experimental fillings, made to show what may be done with gold
foil as comiDared with cast, hammered and annealed gold, as
shown in the previous table. The endeavor was to make the
last six as fillings may be made in teeth in the mouth. None of
these fillings would be moved or shortened by a stress of 300
pounds, while securely held from spreading by the walls of a
cavity in which they might be placed. They are, however, spread
and shortened when the sides are left free to spread under stress.
Gold foil thoroughly welded into fillings, as shown, may be made
as strong as the best cast gold without difficulty, or the use of
but very little more force than may be used in filling teeth. By
very special care, it may be made as rigid — indeed, more rigid
than hammered gold from the ingot, because it is malleted little
by little witliin cavity walls, which prevent free spreading later-
ally. In this experimental work, the walls of the steel matrix
had been finished with fine emery. The gold fillings, even those