Early Deposit of Osteo-Dentine. [Volume: 2, Issue: 11, June, 1861, pp. 607-608]

EARLY DEPOSIT OF OSTEO-DENTINE.

607

that. I see that the different speakers all advocate the use of " Townsend's Cement," which, I have no doubt, owes its celebrity chiefly to the
respectable standing of its inventor; for when it first came out I tried it,
and was rather disappointed at the results. I attributed the failure at
that time, and up till very lately, to the large amount of tin it contained,
and knowing its great affinity for mercury, I concluded that it absorbed
too large an amount of the latter, more than it could retain for any length
of time; but some experiments that I have recently made have shown me
that I have not yet found out the true cause of my failure.
The following is the result of my experiments:I found that 3 grains of pure silver absorbed and retained 3 grains of
hg.; I mean what no pressure that I could exert between the thumb and
palm of the hand could eject.
Three grains of pure tin also absorbed and retained 3 grains of hg.
But what rather astonished me, was that 3 grains of pure precipitated
silver should absorb over 6 grains, more than double its weight of mercury I-while 3 grains of Townsend's silver and tin only absorbs 11 grains
of hg., or half its weight.
Thus we see that, taking pure tin and silver separately, they each absorb their own weight of hg., but when the two are combined, as in
"Townsend's Cement," they only absorb half their weight. Then, again,
the fine division of the base, such as is the case in using precipitated
silver, does not seem to be at all desirable; for I cannot attribute the
large amount of hg. required to amalgamate precipitated silver to any
reason than its minute divisibility.
Under these circumstances, I shall be inclined to think more favorably
of " Townsend's Cement," though I have no doubt that the addition of a
little more silver would tend to make it harder and more durable.
MONTREAL, C. E., June, 1861.
EARLY DEPOSIT OF OSTEO-DENTINE.
BY EDWARD N. BAILEY, D.D.S.
MIss S., about seventeen years of age, of a sanguine and highly nervous temperament, called in March to have some teeth filled. They were
very badly decayed, with the prospect of several exposed nerves; excavated carefully, and, with the aid of chloride of zinc and creosote, prepared and filled the two superior frontals, left lateral and canine, on both
approximal surfaces, being surprised at the extent of the caries without
involving the nerves. Next opened the superior left first bicuspid anterior approximal surface and crown to the posterior indentation, removed
the discolored dentine with caution, (having previously treated with chloride of zinc and creosote,) until I had the base of the cavity exposed
clearly to view; perceived near the centre a small opening with a raised