Page:Popular Science Monthly Volume 27.djvu/558

540 the advantages are claimed for it of self-lubrication, greater wearing capacity than any other metal or alloy, coolness under friction, great tensile strength combined with hardness, and non-liability to fracture.

Phosphor-tin is a compound designed to be added to copper for the making of phosphor-bronze.

The history of the practical manufacture of aluminum does not extend very far back into the past; in fact, its commencement dates within the limits of the present generation. The three International Exhibitions which have been held in Paris since aluminum began to be worked on a commercial scale form so many landmarks in its progress. In 1855 it was met with for the first time in the Palais d'Industrie, in the form of a large bar, and was exhibited as silver produced from clay. In the Exposition of 1867 it was to be seen in a more advanced stage, worked up into castings and various kinds of useful and ornamental articles. There also for the first time was seen the alloy aluminum bronze. The Paris Exhibition of 1878 witnessed the maturity of the aluminum manufacture and its establishment as a current industry, having a regular demand and supply for certain purposes within the limits permitted by its somewhat high price. A little more than two years ago Mr. James Webster perfected his invention for producing aluminum, which is now being practically worked, and gives, it is claimed, alumina without a trace of iron, and free from contamination with other foreign substances. The process is being worked by the Aluminum Crown Metal Company, and the metal itself combines strength and lightness with elegance of appearance and general utility. The bronze is of two kinds—white and yellow—the former being used for cutlery and other table requisites where silver and plated goods are now employed, for metallic fittings, and for every purpose where a non-oxidizing, bright surface, with strength, is desired. The yellow metal is adapted, and is used for articles and for details of machinery where gun-metal and other alloys are now employed. It is said to stand well in engine-bearings, and to give satisfactory results when used in screw-propellers. The bronze is made in five qualities, and each quality is made hard or soft as may be required.

Silveroid, a metal introduced to public notice early in 1884, is an alloy of copper and nickel adjusted with zinc, tin, or lead, in various proportions, according to the purpose for which it is intended; but the secret of success in the manufacture is said to lie in a special method of treatment at a certain point in the process. This alloy is a metal of great whiteness, brilliancy, closeness of grain, and tensile strength.

Cobalt-bronze has been introduced since silveroid, by the same manufacturers, Messrs. Henry Wiggin & Co., who produced that metal. It is whiter and slightly more expensive than silveroid, and is interesting as containing small quantities of cobalt, with the most desirable qualities of that metal, particularly its malleability. It is