The highest grades of carbon or tempering steels are to be recommended for tools which have to withstand shocks, such as for cold chisels or punches. These steels are, however, particularly useful where it is necessary to cut tempered or heat-treated steel which is more than ordinarily hard, for cutting chilled iron, etc. They are useful for boring, for rifle-barrel drilling, for fine finishing cuts, for drawing dies for brass and copper, for blanking dies for hard materials, for formed cutters on automatic screw machines and for roll-turning tools. Steel of this kind, being very dense in structure, should be given more time in heating for forging and for hardening, than carbon steels of a lower grade. For forging it should be heated slowly and uniformly to a bright red and only light blows used as the heat dies out. Do not hammer at all at a black heat. Reheat slowly to a dark red for hardening and quench in warm water. Grind on a wet grindstone. Where tools have to withstand shocks and vibration, as in pneumatic hammer work, in severe punching duty, hot or cold upsetting or similar work, tool steels containing vanadium or chrome-vanadium give excellent results. These are made particularly for work of this kind. CHISELS-SHAPES AND HEAT TREATMENT[1] [Footnote 1: Abstract of paper by HENRY FOWLER, chief mechanical engineer of the Midland Ry., England, before the Institution of Mechanical Engineers.] In the chief mechanical engineer's department of the Midland Ry., after considerable experimenting, it was decided to order chisel steel to the following specifications: carbon, 0.75 to 0.85 per cent, the other constituents being normal. This gives a complete analysis as follows: carbon, 0.75 to 0.85; manganese, 0.30; silicon, 0.10; sulphur, 0.025; phosphorus, 0.025. The analysis of a chisel which had given excellent service was as follows: carbon, 0.75; manganese, 0.38; silicon, 0.16; sulphur, 0.028; phosphorus, 0.026. The heat treatment is unknown. [Illustration: FIG. 83.--Forms of chisels standardized for the locomotive shops of the Midland Ry., England.]