PARTS.
Muria& acid at 220 10 Oil of vitriol 4 Crystallized boracic acid 2 Water 150 Or, Acid muriate of alumine (liquid) 13 Crystallized sulphate of soda 4 Crystallized boracic acid 3 Water 150 Either of these mixtures, with 20 gra. of neutral muriate of gold, constitutes the bath, which is to be used in the fol lowing manner :—A large glass mattress, luted at the bottom, is placed over a circular furnace, so as to have heat readily applied to it ; the solution is to be be put into it, and when at the boiling point, the pieces of introduced, previously cleaned and picked, are to be ntroduced, suspended upon golden wires. After a few minutes, a copper wire is to be im mersed, and left until the gold has ac quired a deep color ; it is then to be withdrawn, but the articles still left in until they have acquired the color neces sary. They are then to be put into warm water, acidulated by sulphuric or acetic acid, to remove particles of oxide of cop per, washed in clean warm water, and dried near a fire. Generally, a single
operation is not enough; for, its a long immersion produces harm from the oxide of copper, it is better to shorten and repeat the operation.
Gold size.—Mix 16 oz. of linseed-oil, 8 oz. of turpentine, 2 oz. of asphaltum, and 1 oz. each of brown umber and of red lead. Or, melt together 1 oz. each gum asphaltum and anime ; I oz. each of li tharge, red lead, and brown umber ; 4 oz. of linseed-oil and 8 oz. of drying oil ; strain.
Gliders' wax is 4 lbs. of bees'-wax, a of verdigris, and also of sulphate of copper, kept in a red heat until the wax has evaporated.
Shell gold may be obtained by amalga mating the metal with S parts of mercury hi a crucible, and then evaporating the mercury. Or, gold leaf may be tritu rated with gum-water, and the gum dis solved and poured off.