3768. To Prepare a Brass Solution

3768.    To Prepare a Brass Solution. For each gallon of water used to make the solution, take 1 pound carbonate of ammonia, 1 pound cyanide of potassium, 2 ounces cyanide of copper, and 1 ounce cyanide of zinc. This constitutes the solution for the decomposing cell. It may bo prepared, also, from the above proportions of carbonate of ammonia and cyanide of potassium, by immersing in it a large sheet of brass of the desired quality, and making it the anode or positive electrode of a powerful galvanic battery or magneto-electric machine; and making a small piece of metal the cathode or negative electrode, from which hydrogen must be freely evolved. This operation is continued till. the solution has taken up a sufficient quantity of the bras to produce a reguline deposit.

3769. To Electroplate with Brass

3769.     To Electroplate with Brass. The solution (see No. 3768 (To Prepare a Brass Solution)) may be used cold; but it is desirable, in many cases, to heat it (according to the nature of the articles to be deposited upon) to 212° Fahr. For wrought or fancy work, about 150° Fahr. will give excellent results. The galvanic battery, or magneto-electric machine, must be capable of evolving hydrogen freely from the cathode or negative electrode, or article attached thereto. It is preferred to have a large anode or positive electrode, as this favors the evolution of hydrogen. The article or articles treated as before described will immediately become coated with brass. By continuing the process, any desired thickness may be obtained. Should the copper have a tendency to come down in a greater proportion than is desired, which may be known by the deposit assuming too red an appearance, it is corrected by the addition of carbonate of ammonia, or by a reduction of temperature, when the solution is heated. Should the zinc have a tendency to come down in too great a proportion, which may be seen by the deposit being too pale in its appearance, this is corrected by the addition of cyanide of potassium or by an increase of temperature.

3770. To Electroplate with German Silver

3770.    To Electroplate with German Silver. The alloy, German silver, is deposited by means of a solution consisting of carbonate of ammonia and cyanide of potassium (in the proportions given above for the brass), and cyanides or other compounds of nickel, copper, and zinc, in the requisite proportions to constitute German silver. It is, however, preferred to make the solution by means of the galvanic battery or magneto-electric machine, as above described for brass. Should the copper of the German silver come down in too great a proportion, this is corrected by adding carbonate of ammonia, which brings down the zinc more freely; and should it be necessary to bring down the copper in greater quantity, cyanide of potassium is added -such treatment being similar to that of the brass before described.