HONE. Under the name of hones, whetstones, or sharpening stones, a variety of finely siliceous stones are employed for whetting or sharpening edge tools, and for abrading steel and other hard surfaces. They generally axe prepared in the form of fiat slabs or small pencils or rods of the material, but some are macle with the outline of the special instrument they are designed to sharpen.

consisting of almost pure quartz, while in others the extremely fine siliceous particles of which impart a remarkably keen edge to the instruments for the sharpening of which they are applied. Hones are used either dry, with water, or with oil, and generally the object to be sharpened is drawn with hand pressure backward and forward over the surface of the hone ; but sometimes the stone is moved over fine-grained sandstone used for sharpening scythes and cutters of mowing machines, and for other like purposes. Next conic the ragstones, which consist of quartzose mica-schist, and give a finer edge than any sandstone. Under the head of oilstones or hones proper the most famous and best-known qualities are the German razor hone, the Turkey oilstone, and the Arkansas stone. The German razor hone, used, as its name implies, chiefly for razors, is obtained from the slate mountains near liatisbon, where it forms a yellow vein of from 1 to 18 inches in the blue slate. It is sawn into thin slabs, and these are cemented to slabs of slate which serve as a support. Turkey oilstone is a close-grained bluish stone containing from 70 to 75 per cent. of silica in a state of very fine division, intimately blended with about 20 to 25 per cent. of calcite. It is obtained only in small pieces, frequently flawed and not tough, so comes from the interior of Asia Minor, whence it is carried Surd and keen in grit, and not easily worn down or broken. Geologically the materials belong to the millstone grit series, and are supposed to be metamorphosed sandstone resulting from the permeation through the mass of heated alkaline siliceous waters. The finer kind is employed for fine cutting instruments, and also for polishing steel pivots of watch-wheels and similar minute .work, the second add courser quality being used for common tools. Beth varieties are largely exported from the United States to all quarters in the form of blocks, slips, pencils, rods, and wheels. During the Centennial Exhibition of 1876 the comparative value of hones per lb was thus quoted - Ark visas 81.50, Washita .35, Turkey 1.00. Among hones of less importance in general use may be noted Charnley Forest stone, a good substitute for Turkey oilstone; Water of Ayr stone, Scotch stone, or snake stone, used for tools and for polishing marble and copperplates ; Idwal or Welsh oiLbone, used for small articles ; and cutlers' greenstone from Snowdon, very hard and close in texture, used for giving- the last edge to lancets,