Note 822 — STEEL.
William Johnston translation
[There can be no question that the hardening or tempering effect produced by the sudden immersion of heated steel in fluids has no relation to the quality of the fluid, save as regards its conducting power of heat. The more suddenly the heat is abstracted from the metal, the greater is the amount of hardness and brittleness. Mercury has been found superior to any other fluid for this purpose, undoubtedly because it is so good a conductor of heat.]