3760. Electroplating with Platinum

3760.    Electroplating with Platinum. This metal has never yet been successfully deposited as a protecting coating to other metals. A solution may bo made by dissolving it in a mixture of nitric and muriatic acids, the same as is employed in dissolving gold; but heat must bo applied. The solution is then evaporated to dryness, and to the remaining mass is added a solution of cyanide of potassium; next, it must be slightly heated for a short time, and then filtered. This solution, evaporated, yields beautiful crystals of cyanide of platinum and potassium ; but it is unnecessary to crystallize the salt. A very weak battery power is required to deposit the metal; the solution should be heated to 100°. Great care must be taken to obtain a fine metallic deposit; indeed, the operator may not succeed once in twenty times in getting more than a mere coloring of metal over the surface, and that not very adhesive. The causes of the difficulty arc probably these: the platinum used as an electrode is not acted upon; the quantity of salt in solution is very little; it requires a particular battery strength to give a good deposit, and the slightest strength beyond this gives a black deposit; so that, were the proper relations obtained, whenever there is any deposit, the relations of battery and solution are changed, and the black pulverulent deposit follows.

3761. Electroplating with Palladium

3761.   Electroplating with Palladium. Palladium is a metal very easily deposited. The solution is prepared by dissolving the metal in nitro-muriatic acid, and evaporating the solution nearly to dryness; then adding cyanide of potassium till the whole is dissolved; the solution is then filtered and ready for use. The cyanide of potassium holds a large quantity of this metal in solution, and the electrode is acted upon while the deposit is proceeding. Articles covered with this metal assume the appearance of the metal; but so far as wo are aware, it has not yet been applied to any practical purpose. It requires rather a thick deposit to protect metals from the action of acids, which is, probably, the only use it can be applied to.

3762. Electroplating with Nickel

3762.      Electroplating with Nickel. Nickel is very easily deposited, and may be prepared for this purpose by dissolving it in nitric acid, then adding cyanide of potassium to precipitate the metal; after which the preELECTROPLATING WITH VARIOUS METALS.

cipitate is washed and dissolved by the addition of more cyanide of potassium. Or the nitrate solution may be precipitated by carbonate of potash ; this should be well washed, and then dissolved in cyanide of potassium; a proportion of carbonate of potash will be in the solution, which has not been found to be detrimental. The metal is very easily deposited; it yields a color approaching to silver, which is not liable to tarnish on exposure to the air. A coating of this metal would be very useful for covering common work, such as gasaliers, and other gas-fittings, and even common plate. The great difficulty experienced is to obtain a positive electrode: the metal is very difficult to fuse, and so brittle that we have never been able to obtain either a plate or a sheet of it. Could this difficulty be easily overcome, the application of nickel to the coating of other metals would' be extensive, and the property of not being liable to tarnish would make it eminently useful for all general purposes.