Hood, Grant · Kansas City, Mo. : Kansas City Jeweler and Optician · leaf 35
ature at which it hardens; and the lowerthe grade, the higher the temperature required in hardening.As we use only that of the very highest grade in our work,and our articles are the most delicate, we must be doublycareful about heating in order to prevent it from burning. 31 MODERN METHODS IN… … Fig. 2—Steel hardened at bright red (slightly burnt). a dull cherry red and plunging it into water, oil or any sub-stance that will quickly cool it. Steel hardened in mercury, nitric acid or cyanide of pot-assium will be very hard and brittle while that hardened inoil, tallow or bees-wax will be…
Clocks and watches
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