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3d.—A porcelain muller, which is to grind the different
substances, of which we shall presently speak.
4th.—A whalebone knife, and not a steel, to avoid oxida-
tion, to serve for tempering the enamel.
5th.—The argillaceous earth of Limoges, known by the
name of Kaolin.
6th.—The earth of Vanvres, already baked.
7th.—Petunze, or flint stone of Limoges, which serves as
a colour to the porcelain.
8th.—The oxide of Titanium.
9th.—The oxide of Zinc.
10th.—The oxide of Uranium.
11th.—The oxide of Manganese.
12th.—The oxide of Gold.
13th.—The muriate of ammonia of Platina.
14th.—The filings of Gold.
15th.—The filings of Platina.
These oxides and metals arc sufficient for the composition
of all the different shades, by beginning with the whitest, and
then with those of deeper colour.
The colour of the natural teeth is ordinarily of a yellowish
white ; this tint is preferable, the teeth of this colour were
always sound and good. Those wherein the yellow pre-
dominates less, and are as white as alabaster, joined to a kind
of transparency, are very inferior, although the finest in ap-
pearance : physiologists have regarded them as signs indica
tive of an infirm constitution. It does not come within our
province to examine this question, which we shall treat on
another occasion, in a work in which we are at present en-
gaged.
The colour of a whitish yellow, like all the others, is sus-
ceptible of alterations which all our organs undergo in time,
whether from accidents, or diseases : of all the ornaments of