Collier's New Encyclopedia (1921)/Abrasives

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ABRASIVES, term applied to substances used in polishing and grinding. They include implements fashioned from natural materials, such as grindstones, millstones, whetstones, etc., mineral substances used in a granulated form and artificial abradants.

The familiar grindstone, known from the earliest times, is made from a gritty tenacious sandstone, found in abundant in Germany and the British Isles, and plentiful in Ohio and other Western States. Millstones and buhrstones, the latter of which are largely imported from France, are used in grinding coarse cereals, cement rock and certain minerals. The increasing use of the roller process in flour-making has decreased the demand for millstones. Oilstones, scythestones, and whetstones are chiefly of American origin, although an appreciable amount is imported from Belgium, Italy, and France. Pumice is a volcanic ash used in scouring powders and soaps. It is found in Utah and Nebraska, and is also brought from the Lipari Islands. Crystalline quartz is used for sandpaper, garnet for woodworking and shoemaking and corundum for metals, the latter being the hardest material known except the diamond. Alundum is a very efficient abrasive for hardened and toughened steels. Carborundum or carbide of silicon is extensively used in difficult tasks. One of the newest abrasives is electrite, which has a composition between alundum and carborundum. The water power of Niagara Falls is used for the treatment and manufacture of abrasives in great plants that have been established near the Falls.