Steel
This wonderful modification of iron is a compound of the metal with from .833 to 1.67 per cent of carbon. In its properties steel combines the fusibility of cast iron with the malleability of wrought iron. Its value for cutting instruments, springs, etc., depends upon its quality of being tempered. When heated to redness and plunged into cold water it becomes hard enough to scratch glass; if again heated and cooled slowly, it becomes as soft almost as ordinary iron, and between these two extremes any required degree of hardness is obtained. As the metal declines in temperature, the thin film of oxide upon its surface constantly changes its color, and it is by these tints that the workman is guided. Thus, a straw-color indicates the degree of hardness for razors, a deep blue for sword-blades, saws, and watch-springs. Steel receives a higher polish than iron, and has less tendency to rust. Nitric acid corrodes it, and leaves the carbon as a dark-gray stain. For the various processes of manufacture see INDIA STEEL; PUDDLE-STEEL; BLISTER-STEEL; CRUCIBLE OR CAST STEEL; BESSEMER STEEL; OPEN-HEARTH OR SIEMENS-MARTIN STEEL; CHROMIUM STEEL; DAMASCUS STEEL; etc.
Steel Bronze is the invention of Col. Uchatius, of the Austrian arsenals. It is simply a substitute for steel in the manufacture of guns. The alloy consists of about 90 copper and 10 tin, and is cast in an iron mould round a forged copper core. The resultant casting, after being turned and bored, is subjected to a process of opening and elongation by means of a conical steel-plug forced through by hydraulic power, resulting, it is claimed, in a tube of equal quality to the best steel tubes. See BRONZE.