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Plate Boiling Powder

Mix equal parts of cream of tartar, common salt, and alum. A little of this powder. added to the water in which silver-plate is boiled, gives to it a silvery whiteness. 3237. Το Remove Dark Stains from Silver. A certain remedy for the most inveterate stains that are sometimes to be seen on teaspoons and other silver ware, is to pour a little sulphuric acid into a saucer, wet with it a soft linen rag, and rub it on the blackened silver till the stain disappears. Then coat the articles with whiting finely powdered and sifted, and mixed with whiskey or spirits of COPPER. wine. When the whiting has dried on, and potassa, after which it must be carefully/ rested a quarter of an hour or more, wipe it collected, washed, dried, ignited, and weighed. with a silk handkerchief, and polish with a This will give the quantity of the oxide from which its equivalent of metallic copper may soft buckskin.

3238. To Remove Egg Stains from be calculated; ; every 5 parts of the former Spoons. To remove the stains on spoons, being nearly equal to 4 of the latter; or, more caused by using them for boiled eggs, take a accurately, every 39.7 parts are equal to 31.7 little common salt moist between the thumb of pure metallic copper. Copper may also be and finger, and briskly rub the stain, which will soon disappear. Then wash. precipitated at once in the metallic state, by immersing a piece of polished steel into the solution; but this method will not give very accurate results. 3242. To Separate Lead from Copper. Copper may be separated from lead by adding sulphuric acid to the nitric solution, 3239. To Clean Gold, Silver, and Copper Coin for Numismatic Collections. Make a weak solution of cyanide of potassium and bathe the coin in it for 2 or 3 seconds, then immediately wash it with a very fine brush, in soap-suds; rinse in clean cold water, and dry and evaporating to dryness, when water in boxwood saw dust. This receipt is partic- digested on the residuum will dissolve out ularly good for fine proof coins. Be careful the sulphate of copper, but leave the sulphate not to let the coins remain in the solution of lead behind. From this solution the oxide of copper may be thrown down as before. longer than the time specified, otherwise they may have a frosted appearance. (See No. 2167.) As the cyanide of potassium is a very deadly poison, great care must be taken by the operator not to use it unless his hands are entirely free from scratches. This solution in nitric acid, and treated as in last receipt.