Part 127

Instead of potassium cyanide alone, a mixture of that and potassium carbonate may be used. After treatment in this way, delicate objects of silver become less brittle. Another way is to put the article in molten sodium carbonate and remove the silver carbonate thus formed, by acetic acid of 50 per cent strength. This process produces the finest possible polish.

The potassium-cyanide process may be used with all small iron objects. For larger ones molten potassium rhodanide is recommended. This converts the iron oxide into iron sulphide that is easily washed off and leaves the surface of a fine black color.

Old coins may be cleansed by first immersing them in strong nitric acid and then washing them in clean water. Wipe them dry before putting away.

«To Clean Old Medals.»—Immerse in lemon juice until the coating of oxide has completely disappeared; 24 hours is generally sufficient, but a longer time is not harmful.

«Steel Cleaner.»—Smear the object with oil, preferably petroleum, and allow some days for penetration of the surface of the metal. Then rub vigorously with a piece of flannel or willow wood. Or, with a paste composed of olive oil, sulphur flowers, and tripoli, or of rotten stone and oil. Finally, a coating may be employed, made of 10 parts of potassium cyanide and 1 part of cream of tartar; or 25 parts of potassium cyanide, with the addition of 55 parts of carbonate of lime and 20 parts of white soap.

«Restoring Tarnished Gold.»—

Sodium bicarbonate 20 ounces Chlorinated lime 1 ounce Common salt 1 ounce Water 16 ounces

Mix well and apply with a soft brush.

A very small quantity of the solution is sufficient, and it may be used either cold or lukewarm. Plain articles may be brightened by putting a drop or two of the liquid upon them and lightly brushing the surface with fine tissue paper. {200}

«Cleaning Copper.»—

I.—Use Armenian bole mixed into a paste with oleic acid.

II.—Rotten stone 1 part Iron subcarbonate 3 parts Lard oil, a sufficient quantity.

III.—Iron oxide 10 parts Pumice stone 32 parts Oleic acid, a sufficient quantity.

IV.—Soap, cut fine 16 parts Precipitated chalk 2 parts Jewelers’ rouge 1 part Cream of tartar 1 part Magnesium carbonate 1 part Water, a sufficient quantity.

Dissolve the soap in the smallest quantity of water that will effect solution over a water bath. Add the other ingredients to the solution while still hot, stirring constantly.

«To Remove Hard Grease, Paint, etc., from Machinery.»—To remove grease, paint, etc., from machinery add half a pound of caustic soda to 2 gallons of water and boil the parts to be cleaned in the fluid. It is possible to use it several times before its strength is exhausted.

«Solutions for Cleaning Metals.»—

I.—Water 20 parts Alum 2 parts Tripoli 2 parts Nitric acid 1 part

II.—Water 40 parts Oxalic acid 2 parts Tripoli 7 parts

«To Cleanse Nickel.»—I.—Fifty parts of rectified alcohol; 1 part of sulphuric acid; 1 part of nitric acid. Plunge the piece in the bath for 10 to 15 seconds, rinse it off in cold water, and dip it next into rectified alcohol. Dry with a fine linen rag or with sawdust.

II.—Stearine oil 1 part Ammonia water 25 parts Benzine 50 parts Alcohol 75 parts

Rub up the stearine with the ammonia, add the benzine and then the alcohol, and agitate until homogeneous. Put in wide-mouthed vessels and close carefully.

«To Clean Petroleum Lamp Burners.»—Dissolve in a quart of soft water an ounce or an ounce and a half of washing soda, using an old half-gallon tomato can. Into this put the burner after removing the wick, set it on the stove, and let it boil strongly for 5 or 6 minutes, then take out, rinse under the tap, and dry. Every particle of carbonaceous matter will thus be got rid of, and the burner be as clean and serviceable as new. This ought to be done at least every month, but the light would be better if it were done every 2 weeks.

«Gold-Ware Cleaner.»—

Acetic acid 2 parts Sulphuric acid 2 parts Oxalic acid 1 part Jewelers’ rouge 2 parts Distilled water 200 parts

Mix the acids and water and stir in the rouge, after first rubbing it up with a portion of the liquid. With a clean cloth, wet with this mixture, go well over the article. Rinse off with hot water and dry.

«Silverware Cleaner.»—Make a thin paste of levigated (not precipitated) chalk and sodium hyposulphite, in equal parts, rubbed up in distilled water. Apply this paste to the surface, rubbing well with a soft brush. Rinse in clear water and dry in sawdust. Some authorities advise the cleaner to let the paste dry on the ware, and then to rub off and rinse with hot water.

«Silver-Coin Cleaner.»—Make a bath of 10 parts of sulphuric acid and 90 parts of water, and let the coin lie in this until the crust of silver sulphide is dissolved. From 5 to 10 minutes usually suffice. Rinse in running water, then rub with a soft brush and castile soap, rinse again, dry with a soft cloth, and then carefully rub with chamois.