By way of experiment, procure two vessels, A and B, fig. 1, in one of them, A, put some dilute sulphuric acid and two plates, one of zinc, Z, the other of copper, _c_, these must not touch each other, but may be separated about half an inch by two or three pieces of wood or cork, and bound round with string; each of these plates must have a piece of wire fastened by soldering to their upper parts. In the vessel B put some solution of sulphate of copper and a small quantity of dilute sulphuric acid, and attach another copper plate to the wire which comes from the copper plate in the acid; this second copper plate is to be immersed in the solution of sulphate of copper, and to the wire from the zinc plate is to be fixed the object to be coated with copper. If a medallion or other object is plaster, it should be soaked in very hot wax and then brushed over with blacklead until the surface is perfectly blackened and bright; the wire should be bound all round the margin and soldered (as it were) with melted wax to the medallion, taking care that this wax also is well coated with blacklead. If the object be now immersed in the sulphate of copper solution and kept at a short distance from the plate (it must not touch it), a coating of copper will soon cover the surface and form a perfect cast, which when of sufficient thickness may be removed by filing the edge all round (if instead of the plaster cast a copper coin or other copper object be used, the blackleading is not required, but the surface must be first made clean and bright). With the same arrangement, but using instead of the sulphate of copper a solution made by dissolving cyanide of silver in a solution of cyanide of potassium, a coating of silver will be deposited, and the same of gold (if cyanide of gold be used), but these coatings will not adhere. If it be intended that the coatings shall adhere, to plate the article with silver or gold, it should be first thoroughly cleaned, then brushed over with a solution of nitrate of mercury, washed in clean water, and put into the gold or silver solution; the nitrate of mercury will cover the copper article with a thin coating of mercury, which will be taken up as the gold or silver is deposited, and this coating will adhere, the article being thus “electro plated.” As in using the solution of sulphate of copper, a copper plate was immersed in the solution and united by the wire to the copper plate in the vessel A, so in using the solution of cyanide of silver, a silver plate must be used, and in the gold solution a gold plate, these plates being dissolved as the metal is deposited, the liquid remaining pretty much the same and serving for future operations. The gold and silver thus deposited are dull, but may be burnished with a steel burnisher, all over or in parts as the design may require. In manufacturing, these processes are much modified, and powerful galvanic batteries or electro-magnets used; in the latter