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Dlssease of the Teeth 91
MINERAL ACIDS.*
Whole sets of teeth are frequently ruined, by the careless
and culpable manner of administering these medicines.
VEGETABLE ACIDS.
It has been said, that vegetable acids cannot act on the teeth,
on account of their having a lesser affinity for lime, than
phosphoric acid has. But here quantity predominates over
affinity,! as any one may satisfy himself, by puttiug a tooth
into almost any vegetable acid, when it will be gradually de-
composed. Vinegar usually contains more or less sulphuric
acid, and therefore acts more energetically. Supertartrate of
potash will decompose a tooth. However, we do not appre-
hend, that the vegetable acids, as we use them for a whole-

* The mineral acids or their preparations are frequently administered
for the cure of disease, and though the physician cautions his patient of
their pernicious effect upon his teeth, if means are not taken to pre-
vent them from coming in contact with the teeth, yet it frequently hap-
pens either from ignorance, carelessness or neglect. Such medicines
should always be drawn through a quill or tube, into the back part of
the mouth, that th ;y may not touch the teeth and the mouth rinced im
mediately after with an alkaline solution. The carbonate of soda will
make a good one.
t AFFINITY OR CHEMICAL ATTRATION.
Affinity or chemical attraction is a power exerted between the particles
of different kinds of matter, causing them to combine so as to form new
bodies, possessing entirely new properties.
" It frequently happens the formation of a new compound is attended by
the destruction of an existing one. The only condition necessary for
this effect, is the presence of some third body, which has a greater affinity
for one of the elements of a compound than they have for each other.
Thus oil has an affinity for the alkalis, as potassa and soda, and will
unite with them, forming soap. But the alkalis have a still greater
attraction for sulphuric acid ; and hesce if this acid be added to a solu-
tion of the soap, the alkali quits the oil, and unites with the acid. Sul-
phuric acid in like manner separates lime from muriatic acid. Thus
ammonia will separate magnesia from sulphuric acid, lime ammonia
and potash lime. Decomposition and combination occur in each of these
instances. .
" The influence of quantity of matter over affinity is universally ad-
mitted."— Turner's Chemistry.