Page 636 - My FlipBook

310 THE TECHNICAL PROCEDURES IN FILLING TEETH.

From this point another short course of alloys only one-
half per cent apart was necessary to find the exact balance which
would produce an alloy that would absolutely lay still while
hardening. When this was found, it was a good formula for that
batch of metals but not for another batch, for the purity might
be different, and the formula for each new batch of metals had
to be found. Therefore, no fixed formula could he good for gen-
eral use.
If it were possible to use chemically pure metals, a fixed
formula would be possible, but such metals would be too expen-
sive for use in dentistry.

EXHIBIT OF UNMODIFIED SILVER-TIN ALLOTS.

Formula.