Crayons for Writing on Glass

Prep. 1. From French chalk, cut into suitable pieces. Marks made with these crayons, when obscured or rubbed out, may be several times revived by simply breathing on the gla . 2. (Brunquelle.) Spermaceti, 4 parts, tallow, 3 parts, wax, 2 parts, are melted together in a cup; and red lead, 6 parts, and carbonate of pota a (in fine powder), 1 part, stirred in; the ma is kept melted and stirred for about half an hour longer, then poured into gla moulds (tubes) of the thickne of a common pencil, and cooled as rapidly as po ible. The ma may be screwed up and down in the tube, and cut to a point with a knife. A crayon is thus obtained which will readily write upon clean, dry gla .