We have already indicated two, the vermilion and the minium, and we shall now mention a few others extensively used.

Prussian Blue

To prepare it, dissolve in water some persulphate of iron; pour into this solution a sufficient quantity of yellow prussiate of potash. It forms a blue precipitate; let it settle; decant the clear liquid; wash the precipitate several times with water; collect it on a filter, and dry it. It is used to color blue.

Chromate Of Lead

Is prepared by adding a filtered solution of acetate of lead to a like solution of bichromate of potash, as long as a precipitate forms. Wash it with water; collect on a filter, and dry it at a gentle heat. It is employed to color yellow.

Other Blue Colors

Instead of Prussian blue, the ultra-marine and smalt can be used.

Green

Employ the green of copper, or a mixture of chrome yellow and Prussian blue.

Violet

Use a mixture of Prussian blue and vermilion.

Black

Use very divided lampblack.

White. Use a little white lead or chalk.

Other Colors

Several experiments have been made of employing colors of coal tar, and have so far sue* ceedcd. As their coloring power is very strong, very little is required to color large quantities of paste. They are used dissolved in alcohol. The powdered gum is colored with it, and dried afterwards. *

Varnish For Matches

Some fancy matches are covered with a light varnish, which is prepared by dissolving black shellac in alcohol. The solution must be very diluted, and is sufficient to give a brilliancy to the matches. The proportions are - Black shellac, 1 lb. Alcohol, 1 qt.

* For their preparation, see Treatise on the Preparation of Coal-tar Colors. Published by XL. C. Baird, Philadelphia.