hasten the expulsion of the teeth from their sockets; and the action of the saliva, if unduly acid, is known to be at least injurious, if not destructive.  Now, the daily employment of a tooth powder sufficiently hard, so as to exert a tolerable degree of friction upon the teeth, without, at the same time, injuring the enamel of the teeth, will, in most cases, almost always prevent the tartar accumulating in such a degree as to cause subsequent injury to the teeth; and a flaccid, spongy, relaxed condition of the gums may be prevented or overcome by adding to such a tooth powder, some tonic and astringent ingredient.  A tooth powder containing charcoal and cinchona bark, will accomplish these results in most cases, and therefore dentists generally recommend such.  Still, there are objections to the use of charcoal; it is too hard and resisting, its color is objectionable, and it is perfectly insoluble by the saliva, it is apt to become lodged between the teeth, and there to collect decomposing animal and vegetable matter around such particles as may be fixed in this position.  Cinchona bark, too, is often stringy, and has a bitter, disagreeable taste.  M. Mialhe highly recommends the following formula:—­

MIALHE’S TOOTH POWDER.

Sugar of milk, one thousand parts; lake, ten parts; pure tannin, fifteen parts; oil of mint, oil of aniseed, and oil of orange flowers, so much as to impart an agreeable flavor to the composition.

His directions for the preparation of this tooth powder, are, to rub well the lake with the tannin, and gradually add the sugar of milk, previously powdered and sifted; and lastly, the essential oils are to be carefully mixed with the powdered substances.  Experience has convinced him of the efficacy of this tooth powder, the habitual employment of which, will suffice to preserve the gums and teeth in a healthy state.  For those who are troubled with excessive relaxation and sponginess of the gums, he recommends the following astringent preparation:—­

MIALHE’S DENTIFRICE.

Alcohol, one thousand parts; genuine kino, one hundred parts; rhatany root, one hundred parts; tincture of balsam of tolu, two parts; tincture of gum benzoin, two parts; essential oil of canella, two parts; essential oil of mint, two parts; essential oil of aniseed, one part.

The kino and the rhatany root are to be macerated in the alcohol for seven or eight days; and after filtration, the other articles are to be added.  A teaspoonful of this preparation mixed in three or four spoonfuls of water, should be used to rinse the mouth, after the use of the tooth powder.

CAMPHORATED CHALK.

Precipitated chalk, 1 lb. 
Powdered orris-root, 1/2 lb. 
Powdered camphor, 1/4 lb.

Reduce the camphor to powder by rubbing it in a mortar with a little spirit, then sift the whole well together.  On account of the volatility of camphor, the powder should always be sold in bottles, or at least in boxes lined with tinfoil.