Although we know these elements only as gases, there is no reason to suppose that their atoms may not be as potent, when added to steel, as atoms of carbon, silicon, phosphorus, or any other substance.
Such are the facts for crucible-steel as far as they are known; it is vastly more expensive than any other kind of steel, yet for the present it holds its own unique and valuable place in the arts.
For all tools requiring a fine edge for cutting purposes, such as lathe-tools, drills, taps, reamers, milling-cutters, axes, razors, pocket-knives, needles, graving-tools, etc.; for fine dies where sharp outline and great endurance are required; for fine springs and fine machinery parts and fine files and saws, and for a hundred similar uses, crucible-cast steel still stands pre-eminent, and must remain so until some genius shall remove from the cheaper steels the elements that unfit them for these purposes.
As stated before, crucible-steel is divided into fifteen or more different tempers, ranging in carbon from .50 to 1.50. Each of these tempers has its specific uses, and a few will be pointed out in a general way.
.50 to .60 carbon is best adapted for hot work and for battering-tools.
.60 to .70 carbon for hot work, battering-tools, and tools of dull edge.
.70 to .80 carbon for battering-tools, cold-sets, and some forms of reamers and taps.
.80 to .90 carbon for cold-sets, hand-chisels, drills, taps, reamers, and dies.
.90 to 1.00 carbon for chisels, drills, dies, axes, knives, and many similar purposes.
1.00 to 1.10 carbon for axes, hatchets, knives, large lathe-tools, and many kinds of dies and drills if care be used in tempering them.