. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 293 The model to be used in the bath, either of gold, silver, or copper, is to have soldered on the back a piece of copper wire, for a conduc- tor ; and the model is to be well cleaned with plumbago and a brush, and its back fixed in wood, leaving only the required surface exposed. Take a piece of zinc, about five ounces, and fasten on a screw, then attach the copper wire to the screw, and place the piece of zinc in one of the
. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 293 The model to be used in the bath, either of gold, silver, or copper, is to have soldered on the back a piece of copper wire, for a conduc- tor ; and the model is to be well cleaned with plumbago and a brush, and its back fixed in wood, leaving only the required surface exposed. Take a piece of zinc, about five ounces, and fasten on a screw, then attach the copper wire to the screw, and place the piece of zinc in one of the tubes D, suspending at the same time the model through tlie centre hole, E, of the plate B, into the bath; when the plate is taken out of the bath, and taken oflf the model, it will exhibit a bur- nish polish or dead appearance, according to the preparation of the model ; it will also be found to be good and pliable metal, bearing to be made several times hot without injuring or destroying the copy of the finest engine-turning or engraving. Preparation for Silvering.—First dissolve 700 drams of sulphate of soda recently prepared in four parts of warm filtered water. Se- condly, dissolve 25 drams of carbonate of soda (when for use with electric currents, but when to act by simple immersion, 75 drams are used) in a pint of warm filtered water. Thirdly, dissolve 31 drams of moist carbonate of silver. When these solutions are cold, mix the sulphate of soda and the carbonate of soda together, then add the rarbonate of silver, and stir all well with a glass stick till the silver is well incorporated. This preparation is to be used cold. Battery.—When electric currents are to be used with the above pnrposes, it is preferred to employ the battery shown in fig. 2, which is constructed as follows : a is a glass jar ; b, a tube of charcoal; c, a porous vessel; and e, a tube of amalgamated zinc. In making small articles of silver, or of gold as hereafter explained, such as watch- oase
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