A treatise on electro-metallurgy; embracing the application of electrolysis to the plating, depositing, smelting, and refining of various metals, and ... of printing surfaces and art-work, etc

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1891 Excerpt: ...electrodes, the points of nearest approach being those which receive the deepest cut. The resulting plate is used precisely as an ordinary etched copper plate; and, indeed, it is such, the processes employed to produce them being identical except in the method of biting-in the lines. To obtain anything but crude results, however, by these processes demands much experience and attention, as it is frequently necessary to stop-out some of the finer lines to prevent further action at different periods of the process, and practice and artistic skill alone can guide the operator in this matter. An ingenious process for obtaining nature-prints of leaves and similar bodies is sometimes used. The leaf is placed between two plates, one of polished steel, the other of soft lead, and is then passed between rollers which exert a considerable pressure. The subject of reducing copper from its ores and refining the crude metal will be dealt with in a separate chapter later in the Work. CHAPTER IX. THE ELECTRO-DEPOSITION OF SILVER. The electro-plating of articles with silver was one of the earliest applications of electrolysis, because it produced a material analogous to, but cheaper than, the older "silver-plate," in which the base metal was covered mechanically with a layer of silver; and even at the present day, when electrolysis is used to obtain coatings of so many different metals for such varied purposes, the deposition of silver must, perhaps, take the foremost place, both in respect of universality of practice and value of results. Deposition By Simple Immersion, Or Whitening. Silver, as compared with most metals, is very electro-negative, and hence all the base metals are capable of exchanging places with it when dipped into a solution of one of its salt...