As forecast by Mushet, the essential constituent of the new steels is the metal, tungsten. But tungsten alone cannot give the desired property. Mushet, it will be remembered, was the metallurgist whose patents for the use of manganese in steel Bessemer was obliged to recognize to make his process a success, though the metal had earlier been used in crucible steel. The air-hardening property of Mushet’s steel was contributed by a happenstance combination of tungsten and this same metal, manganese. It later developed that tungsten and chromium were the best hardening elements and these have maintained their place, though refinements of the past few years have made use of vanadium, and, more recently, cobalt in addition. Usual amounts may be said to be tungsten 14 to 25 per cent, chromium 2 to 7 per cent, with vanadium ½ to 1½ per cent, and cobalt up to 4 per cent, perhaps. The carbon content is usually .6 to .8 per cent. Sometimes another comparatively rare metal, molybdenum, is used in high-speed steels in place of part of the tungsten, but its use does not seem to be on the increase. Manufacturers differ considerably in formulas. It will be noticed that at best there is left room for only 70 or 80 per cent of iron in the alloy. From certain standpoints, the high-speed steels might not at first thought be called “steels” at all since carbon seems to be of so little importance. They might be considered to be low carbon alloys somewhat similar to the newer “stellite” (an alloy from which tools are made), which contains little or no carbon and no iron but is made up mainly of cobalt and chromium. They fit in, however, with the general and very comprehensive scheme of classification of the iron-carbon alloys which has been developing over a period of twenty years and there is no doubt among metallurgists and metallographists that, as is the case with the alloy steels described above, they are iron-carbon alloys—in other words, steels—the properties of which have been greatly modified through the presence of the other elements. Carbon, therefore, is an essential, though it is much less in amount than in the carbon tool steels. The hardening and softening properties, also, very definitely classify these alloys with the “tool steels.” Stellite cannot be softened. As with the carbon tool steels, most of the high-speed steels are made by the crucible method, though a small but increasing amount is of late being produced in the electric furnace. After careful pouring into small ingots and cooling, the ingots are removed from the iron molds and “topped” to remove any “pipe” or unsound portion. Then, if without defect and satisfactory as to analysis, they are slowly and carefully heated to forging temperature and are hammered out into bars. By this method they are taken nearly down to the final size desired. The bars are finished by rolling to size. After careful annealing they are ready for shipment to the tool maker.