236 ANNUAL OF SCIENTIFIC DISCOVERY. 



proportions. For the well known alloy, brass, carbonate of ammonia, 

 and cyanide of potassium are used in the following proportions : viz. 

 to each or every gallon of water are added 1 Ib. of carbonate of am- 

 monia, 1 Ib. cyanide of potassium, 2 ozs. of cyanide of copper, and 1 

 oz. of cyanide of zinc ; these proportions may be varied to a consider- 

 able extent. Or the patentees take the before-named solution of car- 

 bonate of ammonia and cyanide of potassium, in the proportion of 

 1 Ib. of each to one gallon of water ; and they take a large sheet of 

 brass of the desired quality, and make it the anode or positive elec- 

 trode, in the aforesaid solution, of a powerful galvanic battery or mag- 

 neto-electric machine, and a small piece of metal, and make it 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 brass to produce a regular deposit. 

 The solution may be used cold ; but it is desirable, in many cases, 

 to heat it (according to the nature of the article or articles to be 

 deposited upon) up to 212 Fah. ; for wrought or fancy work, 

 about 150 Fah. The galvanic battery, or magneto-electric ma- 

 chine, must be capable of evolving hydrogen freely from the ca- 

 thode or negative electrode, or article attached thereto. It is pre- 

 ferred to have a large anode or positive electrode, as this favors 

 the evolution of hydrogen. The article or articles, treated as be- 

 fore described, will immediately become coated with brass : by con- 

 tinuing 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. 



The alloy, German silver, is deposited by means of a solution, con- 

 sisting of carbonate of ammonia and cyanide of potassium (in the 

 proportions previously given 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 solu- 

 tion 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 car- 

 bonate 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. 



The solutions for the alloys of gold, silver, and other alloys of 

 metals, are made in the same manner as above stated, by employing 

 anodes of the alloy or alloys to be deposited ; or by adding to the so- 

 lutions the carbonates, cyanides, or other compounds, in the propor- 

 tions forming the various alloys always using, in depositing, an 



