The pure white tint of nickel, its inoxidisability, and, therefore, the ease with which it is kept clean, have caused it to come into general use for metal fittings, especially those of vessels and carriages, as well as for the bright parts of engines and machines. But, on account of the relatively high price hitherto obtained by nickel, it has been employed chiefly in the state of electro-deposit.

Nickel-plating is effected by two processes, one hot and the other cold. In the former a solution of sulphate of nickel is used in an enamel cast-iron trough. This is the more rapid method, but its results are not so satisfactory as in the cold process. The latter is effected with a bath of double sulphate of nickel and ammonia, the articles to be nickelised being suspended by a platinum wire attached to the positive pole of the battery, while a plate of pure nickel, to restore the metal to the bath, is put in connection with the negative pole. The nickelisation thus produced, though it requires a longer time than the other process is finer and more durable.

There are, however, several objections to nickel-plating. The process is injurious to the workmen engaged in it. The thin coating of nickel is liable to peel off, and in the case of parts exposed to wear, or even with cleanings, in course of time, the nickel becomes so worn off at the edges as to expose the base metal beneath. Besides, nickelisation does not entirely prevent the oxidisation of steel and iron.

A French Company, La SociÉtÉ FranÇaise Anonyme de Nickel, briefly referred to in connection with the Applied Science Exhibition, Paris, are endeavouring to supersede the nickelisation of brass and copper by the use of solid nickel bronze, which is thus obtained. The ore, garnierite, extensive deposits of which exist in New Caledonia, the French penal settlement, is worked by Messrs. John Higginson and Co., of Noumea, the concessionaires. It is by them subjected to a roasting on preliminary fusion, which forms a regulus, containing from 60 to 70 per cent. of metallic nickel. This substance is shipped to the works of the company at Septemes, near Marseilles, where it is smelted into ingots and granule, containing 99½ per cent, of pure nickel, and ¼ per cent, of utilisable metallic substances. The extent of the mineral deposits in New Caledonia, the reduction in the cost of freight owing to the concentration of metal through the preliminary fusion, and the economy effected by the new methods of reduction devised by M. Jules Garnier, enable the company to sell the pure metal at about one-half the price it obtained three years ago.

For a long time past, efforts have been made to work nickel, but without success, until the present year, because it was found too brittle; now, however, pure nickel has been rolled and forged; cups, knives, and other articles have been formed of it. As a rule, the pure nickel is formed by the founder with various proportions of copper, zinc, and tin, according to circumstance, to form nickel bronze; but at least 20 per cent. of nickel is required to secure inoxidisability, and to give the desired tint. All articles that are now made of brass or copper nickelised may be produced in solid white nickel bronze, by the same processes, and with the same plant, and at practically the same cost; they are also 20 per cent. stronger, so that in many cases they may be made so much lighter. The great strength and the property of non-oxidisation render this alloy eminently suitable for mathematical and musical instruments. A small quantity of nickel added to steel increases its hardness, and renders it inoxidisable, while edge-tools made of the alloy stand better than those of ordinary steel. A nickel bell metal is also found to give good results. The Paris Exhibition of 1878 proved the action of a totally new system of metallurgy in connection with this beautiful metal, and that of 1879 showed its practical introduction into most branches of manufacturing industry.—Journal of the Society of Arts.