3199. Gold Coloring Solution

3199.    Gold Coloring Solution. Take 1 ounce nitrate of soda, and 1/2 ounce chloride of sodium, and dissolve in a slight excess of warm water, afterwards adding to the solution about 5 drachms hydrochloric acid. The solution should be kept boiling while the work is in it.

3200. To Clean Gold after it is Soldered

3200. To Clean Gold after it is Soldered. Put it through the same process as silver (see No. 3222 (To Clean Silver after it is Soldered)), but, instead of alum-water, boil it in wine and sal-ammoniac.

3201. To Restore the Color of Gold after Soldering

3201.    To Restore the Color of Gold after Soldering. Boil the gold, after soldering, in diluted oil of vitriol; rinse in clean water, polish with Tripoli mixed in oil (sweet oil is best), wash and gloss with crocus on a clean cloth.

3202. To Clean Gold

3202.      To Clean Gold. Dissolve a little muriate of ammonia in urine; boil your soiled gold therein, and it will become clean and brilliant.

3203. To Clean Gold Ornaments

3203.       To Clean Gold Ornaments. Gold ornaments may also be thoroughly cleaned by immersion for a few seconds in a ■weak solution of ammonia. Then wash with soap and water.

3204. Polishing Powder for Gold Articles

3204. Polishing Powder for Gold Articles. Dr. W. Hofman has analyzed a polishing powder sold by gold workers in Germany, which always commands a very high price, and hence, it may be inferred, is well adapted for the purpose. He found it to be a very simple composition, being, a mixture of about 70 per cent, sesquioxide of iron (iron rust) and 30 per cent, sal-ammoniac. To prepare it, protochloride of iron, obtained by dissolving iron in hydrochloric acid, is treated with liquid ammonia until a precipitate is no longer formed. The precipitate is collected on a filter, and, without washing, is dried at such a temperature that the adhering sal-ammoniac shall not be volatilized. The protoxide of iron precipitate at first becomes charged with sesquioxide.