Electro-plating is one of the great industrial applications of electricity which had its origin in, and has grown into extensive use in, the Nineteenth Century. It originated with Volta, Cruikshank, and Wollaston in the very first year of the century. In 1805 Brugnatelli, a pupil of Volta, gilded two large silver medals by bringing them into communication by means of a steel wire with the negative pole of a voltaic pile and keeping them one after the other immersed in a solution of gold. In 1834 Henry Bessemer electro-plated lead castings with copper in the production of antique relief heads. In 1838 Prof. Jacobi announced his galvano-plastic process for the production of electrotype plates for printing. In the same year he superintended the gilding, by electro-plate, of the iron dome of the Cathedral of St. Isaac at St. Petersburgh, using 274 pounds of ducat gold. In 1839 Spencer described an electrotype process and carried the date of his operations back to September, 1837. In 1839 Jordan also describes an electro-plating process. In 1840 Murray used plumbago to make non-conducting surfaces conductive for electro-plating. In 1840 De Le Rive made known his process of electro-gilding, employed by him in 1828, and in the same year (1840) De Ruolz took out a French patent for electro-gilding, and in the following year formed electro deposits of brass from cyanides of zinc and copper. In 1841 Smee employed his battery for electro-plating with various metals. In 1844 there were published the electro-plating experiments of Dancer, made in 1838. In 1847 Prof. Silliman imitated mother-of-pearl by electro-plating process.
FIG. 71.—ELECTRO-PLATING ESTABLISHMENT.
In the last half of the century the production of electrotype plates for printing in books, and for the production of rollers for printing fabrics, and the extensive art of electro-plating with gold, silver, nickel and copper, has grown to enormous proportions, but the fundamental principles have not materially changed. The dynamo, however, has generally supplanted the voltaic battery in this art. The deposition of silver and gold on baser metals not only increases the ornamental effect, but prevents oxidation. Silver plated goods for the table and articles of vertu are to be found everywhere. Nickel is employed for cheaper ornamental effect, and copper finds a large application for electrotypes for printing and for coating iron castings as a protection against rust. In [Fig. 71], which shows the interior of an electro-plating establishment, the dynamo is shown on the right connected by wires with two horizontal rods running along the wall and across the various tanks containing the plating solution. On the tanks are rods supporting the articles to be plated, which are suspended in the solution. Similar rods support the opposite electrodes of the tank. Wires connect these rods to the rods on the side of the wall, and to the opposite poles of the dynamo.
FIG. 72.—EDISON’S ELECTRIC PEN.
The electric pen of Edison, brought out in 1876 (U. S. Pat. No. 196,747, Nov. 6, 1877), is one of the simple applications of electricity, which for a number of years was in quite general use for making manifold copies of manuscript. In the illustration, [Fig. 72], this is shown. It comprises a stylus b reciprocated in a tube a by the vibratory action of an armature k over the poles of an electro-magnet, supplied with a suitable current and vibrating contacts l h. The stylus was rapidly reciprocated, and as the operator traced the letters on the paper, the stylus produced a continuous trail of punctures which permitted the paper to be used as a stencil to make any number of copies. It has, however, been rotated out of existence by manifolding carbon paper, and the almost universal use of the typewriter.