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120 THE TREATMENT OF TEETH
alloys, when used some considerable time after they
have been reduced to filings, will generally mix into
a smooth plastic mass quite readily, and with less
mercury. This ageing of alloy filings is considered
by Dr. Flagg to be a distinct advantage in all cases
while Dr. Black, on the contrary, considers that
with certain formulae it is a detriment. The ad-
vantage of using an untempered alloy consists not
only in its superior mixing and working properties,
but in the fact that, when once it is untempered, it
is likely to behave always in the same way. The
advantage of using alloys that give good results in
the untempered state is therefore manifest. When
experts differ it is hard for an ordinary man to
know which line to follow. The difference between
Dr. Flagg's conclusion, and that arrived at by Dr.
Black in this respect, seems to be, that while the
former holds that all alloy filings are improved
with age, and slow untempering, the latter con-
siders that the composition or proportions of the
alloy should vary according to Avhether the filings
are used in a tempered or untempered state.
Apart from the superior mixing qualities of the
majority of untempered alloys, the trouble neces-
sitated in keeping the alloy in the ingot form, and
filingf off sufficient for the case in hand each time, in
I
order to secure even results, is sure to prevent its
120 THE TREATMENT OF TEETH
alloys, when used some considerable time after they
have been reduced to filings, will generally mix into
a smooth plastic mass quite readily, and with less
mercury. This ageing of alloy filings is considered
by Dr. Flagg to be a distinct advantage in all cases
while Dr. Black, on the contrary, considers that
with certain formulae it is a detriment. The ad-
vantage of using an untempered alloy consists not
only in its superior mixing and working properties,
but in the fact that, when once it is untempered, it
is likely to behave always in the same way. The
advantage of using alloys that give good results in
the untempered state is therefore manifest. When
experts differ it is hard for an ordinary man to
know which line to follow. The difference between
Dr. Flagg's conclusion, and that arrived at by Dr.
Black in this respect, seems to be, that while the
former holds that all alloy filings are improved
with age, and slow untempering, the latter con-
siders that the composition or proportions of the
alloy should vary according to Avhether the filings
are used in a tempered or untempered state.
Apart from the superior mixing qualities of the
majority of untempered alloys, the trouble neces-
sitated in keeping the alloy in the ingot form, and
filingf off sufficient for the case in hand each time, in
I
order to secure even results, is sure to prevent its
