Page 381 - My FlipBook

377

were again soluble in dilute nitric acid, giving a copious pre-
cipitate with solution of acetate of lead
: this precipitate,
washed, dried, and exposed to a flame urged by a blow-
pipe, fused into a globule, accompanied with a bright phos-
phorescent appearance, and was, therefore, phosphate of
lead.
The substance not soluble in nitric acid, was washed and
dried at 212°, weighed 9 grains.
The separated solution was of a yellow colour ; the addi-
tion of nitric acid produced no precipitate, but lost colour,
which was recovered by ammonia.
The 9 grains of residuum, after treatment of the potash,
were placed in boiling concentrated nitric acid, by which
they were completely dissolved ; and by the test of tannin
proved the cartilage to have been gelatinized.
Tartar of the teeth consists of,
Phosphate of lime, • - ... 35
Fibrina, or cartilage, 9
Animal fat, or oil, 3
Loss, 3

50

Next to caries, nothing is more destructive to the health
of the mouth than this substance. It is apt to be insinuated
between the gums and teeth, passing upon the alveolar pro-
cesses, producing irritation, inflammation, and suppuration of
the former, and caries and absorption of the latter ; and con-
sequently, it causes the teeth to be loosened, and ultimately
to fall out. This is the cause of the loss of the teeth in
elderly persons, which otherwise were perfectly sound, of
which I have spoken before. By causing a diseased state of
the gums, it affects the breath, and causes it to be very of-
48