... Giving a Tempered-Blue Color to the Steel Plate and Malleable Iron Castings of a Roller Skate.—In order to obtain an even blue, the work must have an even finish, and be made perfectly clean. Arrange a cast-iron pot in a fire so as to heat it to the temperature of melted lead, or just below a red heat. Make a flat bottom basket of wire or wire cloth to sit in ... — Burroughs' Encyclopaedia of Astounding Facts and Useful Information, 1889 • Barkham Burroughs