Home › Photography › Grain Gold

Grain Gold

Cupelled gold, 1 part; silver, 3 parts; melt and pour in a small stream into water; dissolve out the silver performed by adding 3 parts of silver to one of the cupelled sample, and fusing them to gether, by which the gold is reduced to one fourth of the mass, or even less; hence the with nitric acid, and heat the grains to redname. In this state nitric acid will dissolve ness. Used to make preparations of gold. out the silver, which brings us to the next 3195. Liquid Gold. Agitate ether operation. In many cases the operation of with a solution of terchloride of gold for some quartation is performed conjointly with that time, allow it to repose, and decant the suof cupellation. pernatant portion. Naphtha and essential Parting. The alloy of gold and silver oils possess the same property as ether, of formed by quartation is next hammered or taking gold from its solutions. This liquid rolled out into a thin strip or leaf, curled up was formerly held in great esteem as a corinto a spiral form, and submitted to the ac- dial medicine. It is now only employed for tion of nitric acid, specific gravity 1.3, dilu- writing on steel, gilding, &c. As it dries, ted with half its weight of water; this being it leaves a coating of pure gold. (Sce No. poured off, another quantity of acid, of about 3585.) 1.26, and undiluted, may be employed. In 3196. Το Make Watch Hands Red. cach case the acid should be boiled upon the Mix to a paste over a lamp, 1 ounce carmine, alloy for about a quarter of an hour. In the 1 ounce chloride of silver, and 1/22 ounce tinners' first case the quantity of fluid should be about japan. Put some of the paste on the hands, ounces, and in the second 1½ ounces. The and lay them face upwards on a sheet of copsecond part of the operation of parting is called the reprise. If the acid be used too strong it leaves the gold in a state of powder, otherwise the metal preserves its form throughout the process of parting. It is next carefully collected, washed, and dried.

Annealing. The sample of pure gold has now only to be annealed, which is done by putting it into a small porous crucible, and heating it to redness in the muffle. per, holding it over a spirit lamp until the desired color appears on them. 3197. French Method for Coloring Gold. A solution is made of 2 parts nitre, 1 part Roman alum, and 1 of sea salt. The jewels or articles of gold are kept in the solution at a boiling point for from 15 to 25 minutes; and then washed in water. The surface of the gold is dull, but perfectly uniform, and ready for burnishing.