Page 139 - My FlipBook

FILLING TEETH 123

mortar, and by a circular motion, occasionally
reversed, drawing in the filings little by little."
" The mass is then gathered by the finger from
the mortar into the palm of the hand, and is
kneaded until it becomes a button." The button
is then spread out by careful and thorough rubbing
in the palm with the finger, again gathered up into
a button, and this process is repeated until a per*
fectly homogeneous plasticity is attained. " It is
during this manipulation, oftentimes repeated, that
the ' crepitation ' of an amalgam is heard."
Dr. Black says that the proper amount of mercury
should be mixed with the alloy to begin with, not
so much because squeezing out will injure it, but
because the mix cannot be properly kneaded if
there is too much mercury in it. He also says that
the alloy he has found to give the best results works
into an amalgam very slowly, and it requires a great
deal of kneading to obtain the proper condition of
the mass. " To get a smooth-v/orking property, they
should be laieaded a considerable time, and you
cannot do this kneading properly if there is too
much mercury in the mass. They need to be
kneaded until the granular appearance has fairly
disappeared, and they will work into a plastic
state."
Diflferent alloys will require different proportions