3597. Boettger's Method of Gilding Glass

3597.    Boettger's Method of Gilding Glass. Boettger has modified Wernicke's process for throwing down gold on glass as follows: He prepares the soda solution by dissolving 6 grammes (921/2 grains) caustic soda in 100 cubic centimeters (84/100 gill) water; the reducing fluid, to be made when washed, by dissolving 2 grammes (31 grains) common starch-sugar (glucose) in 24 grammes (370 grains) distilled water, and adding 24 cubic centimeters (1/5 gill) alcohol of 80 per cent., 24 cubic centimeters aldehyde of .870 specific gravity : neutral solution of chloride of gold, 1 gramme (15.4 grains) of gold in 1,200 cubic centimeters (21/2 pints) water. Four volumes of the gold solution are mixed in a suitable vessel with one volume soda solution and 1.16 volumes of the reducing liquid, and the liquid rapidly poured into the hollow glass globe to be plated. Five minutes is sufficient to insure the deposit of a thin film of gold, but it is better to allow more time. Flat plates of glass can be laid upon the surface of the liquid, as in the silvering process; the surfaces of the glass should be carefully cleaned with soda and alcohol, and not with acids. The greater part of the gold is thrown down in flocculi, and can be recovered for subsequent use - the amount deposited upon the glass being very small. The mirrors are to be well washed and dried in the air. "Where the baths are heated, the deposition of gold takes place more rapidly, but not so fine; it is better to keep the temperature below 140° Fahr, and to allow the metal coating to form slowly.

3598. Upton's Gold Detergent

3598. Upton's Gold Detergent. Quicklime, 1 ounce; sprinkle with a little hot water to slack it, then gradually add 1 pint boiling water, so as to form a milk; dissolve 2 ounces pearlash in 11/2 pints boiling water; mix the two solutions, cover up, agitate occasionally for an hour, allow it to settle, decant the clear, put it into flat half-pint bottles, and cork them down well. It is used to clean gilding, etc., either alone or diluted with water. It is applied with a soft sponge, and then washed off with clean water. It is essentially a weak solution of potassa, and may be extemporaneously prepared by diluting liquor of potassa with about 5 times its volume of water.

3599. Gruene's Method of Gilding and Silvering Silk

3599. Gruene's Method of Gilding and Silvering Silk. By a formula published by Gruene, for silvering or gilding silk, the silk is to be soaked with a 5 per cent, solution of iodide of potassium, and dried; then (in non-actinic light, see No. 3140 (Precautions to be Observed in Making a Picture)), dipped in a 5 per cent, solution of nitrate of silver, containing a few drops of nitric acid, and well drained; next exposed for a few minutes to sunlight, and then dipped in a 2 per cent, solution of sulphate of iron. It immediately becomes gray, from reduction of metallic silver, and, after washing and drying, only requires burnishing in order to acquire the metallic lustre. By repeating this treatment, varied, however, by adding a little free iodine to the solution of iodide of potassium, the silver deposit becomes stronger. By laying the silvered silk in a very weak solution of chloride of gold, the silver becomes chloride, and gold is deposited; and by then removing the chloride of silver by a solution of hyposulphite of soda, washing, drying, and burnishing, the appearance of gilding is produced, if the deposit of metal be sufficiently thick. The purest chemicals must bo used in all gilding processes, in order to secure satisfactory results.