Smalt, a species of glass of a dark-blue colour; and which, on levigating it, assumes a beautiful shade; resisting the action of air and fire : hence, if it could be rendered sufficiently fine, it would prove an excellent substitute for ultrama-rine.

Smalt is prepared, by melting one part of calcined cobalt, with two of pulverized flint, and one of potash. At the bottom of the crucibles, which are employed in manufacturing this compound, there is generally found a regulus of a whitish colour, inclining to red, and rather brittle; this, on being again melted, and becoming cold, separates into two parts; namely, that which settles at the bottom, is the true cobalt, and is used to increase the quantity of smalt ; the other is called bismuth; to which we refer.

Smalt is employed in various branches of the arts and manufactures ; as likewise by clear-starch-ers, in getting up fine linen; and by whom it is termed Powder-Hue.