Steel plating ou copper plates and type is extensively practised, by one method ; in proceeding to prepare for work, the trough is filled with water in combination with hydrochlorato of ammonia, sal-ammoniac, in the proportion of 1000 lb. by weight of water, to 100 lb. of hydroehlorate of ammonia. A plate of sheet iron nearly as long and as deep as the trough, is attached to the positive pole of the battery, and immersed in the solution. Another plate of sheet iron about half the size of the other is attached to the negative pole of the battery, and immersed in the solution, and when the solution has arrived at the proper condition, which will require several days, the plate of iron attached to the negative pole is removed, and the printing surface to be coated is attached to this pole, and then immersed in the bath till the required coating of iron is obtained. If, on immersing the copper plate in the solution, it is not immediately coated with a bright coating of iron all over, the bath is not in a proper condition, and the copper plate is to be removed and the iron plate attached and returned into the solution. The time occupied in obtaining a proper coating of iron to a
printing surface varies from a variety of causes, but a copper plate should not be allowed to remain in the bath and attached to the negative pole of the battery after the bright coating of iron begins to show a blackish appearance at the edges. Immediately on taking a copper plate from the bath, great care is to be observed in washing off the solution from all parts, and this may bo most con veniently done by causing jets of water forcibly to strike against all parts of the surface. The plate is then dried and washed with spirits of turpentine, when it is ready for being printed from in the ordinary manner.
Roseleur, Galvanoplastic Manipulation' (Philadelphia : 1872); A. Watt, Electro-Motallnrgy ' (London : 1874); J. T. Sprague, Electricity, &c.' (London : 1875) ; J. Napier, 3 1.
Manual of Electro-Metallurgy ' (London : 1876); G. Gore, ' Art of Eleetro-Metallurgy ' (London : 1877); E. Spon, Workshop Receipts' (London : 1879); J. W. Urquhart, Electro-Plating ' (London: 1880). E. S.