They produced new compositions the quenching of which could be from temperatures greatly in excess of those which tool makers for centuries had held to be ruinous and which really are ruinous to carbon tool steels. The best results were obtained when the new steels were quenched by plunging in oil from close to their melting points—a dripping or “sweating” heat as it is called. This was something entirely new but it developed that after proper drawing, steels quenched from these extreme temperatures, would stand up under lathe speeds as great as 200 or 300 feet per minute. Compare these with the miserable speeds of 20 or 30 feet per minute, which were the average performances of the best carbon steels. The secret of Taylor and White’s treatment was not long in coming out and soon high-speed steel makers in Europe and America were vying with each other in production of finer and finer high-speed steels. The progress which has been made during the last twenty years and particularly during the past ten has been astounding. Improvement has followed improvement in composition, manufacture and heat treatment, so that to-day, instead of the cut at 30 feet per minute, which was a high figure with carbon steel tools, the modern lathe or shaper tool often works at 300 or 400 or more feet per minute, and, with sufficient power behind it, at somewhat lower speeds plows out ½ inch deep and ¾ inch wide chips so fast that their removal to keep the machine clear is no mean problem. Often 2,000 pounds of the material per hour can be thus cut away with one tool. As suggested, the new steels do not suffer such loss of temper from the heat generated by the friction of the tool in the metal as occurs with carbon steel tools. In fact, tools of high-speed steel work best after “warming up” and they can run for a considerable period of time with the point of the tool red-hot, though such is not advisable. As is readily seen the essential property of the high-speed steels is the so-called “red hardness” which is the ability to retain hardness at red heat. This is several hundred degrees in excess of the temperatures at which the carbon tool steels quickly lose their “temper.”