Although titanium is unimportant commercially, yet when al loyed with other elements it forms a number of useful products. Four of these alloys—ferrocarbon titanium, carbon-free ferro titanium, cuprotitanium, and manganotitanium—are in commer cial use. Ferrocarbon titanium is made by reduction of ilmenite with coke in an electric furnace, or by charging rutile mixed with carbon into an electric furnace containing molten iron or steel. The alloy so produced has a high carbon content (5 to 8%) but this can be reduced below 1% by remelting with rutile. Ferro carbon titanium normally contains Ti 15-18, C 7, Si 1.5%, the rest being iron and small quantities of impurities. The carbon free ferrotitanium is produced by the thermit process. The finely powdered ilmenite (or oxides of iron and titanium) mixed with aluminium powder, in the correct proportions, is ignited by means of a fuse. A rapid reaction takes place in which the oxides are reduced to the elemental condition and an alloy of the following composition is produced: Fe, 67-69; Ti, 25; Al, 5-6; Si, I-1.05; P, o.o5; S, o.o %. Cuprotitanium is made by the alum ino-thermic reduction of rutile to which copper has been added, and manganotitanium is similarly produced by the reduction of rutile to which manganese or its oxide has been added. Titanium in the form of its alloys acts as a final deoxidizer and denitro genizer for metals. The addition of the ferro-alloys to steel yields a cleaner and sounder product, whilst the cuprotitanium and manganotitanium are used as deoxidizers in brass and bronze prac tice. Titanium in the form of its compounds finds many useful applications. Ilmenite and rutile, as well as artificial titanium
dioxide, have been used in the making of arc-lamp electrodes. Titanium compounds have proved of value as pigments in the paint industry, dyes and mordants in the textile and leather in dustries, refractory colouring materials for use in ceramics and in the manufacture of artificial teeth. Titanium white, is put on the market as a pigment to compete with white lead and zinc white.
Titanium forms a wide range of salts in which it exhibits val encies of 4, 3, and 2. Titanium tetrachloride, which may be conveniently prepared by passage of chlorine over heated titanic oxide and carbon, is a colourless liquid boiling at 136.4° C. It fumes excessively in the air and was used as a smoke-screen during the World War. By electrolytic reduction of a solution of the tetrachloride in hydrochloric acid, a violet solution of titanium trichloride is obtained. This compound has pronounced reducing properties and has been utilized for many useful volu metric processes (Knecht and Hibbert, New Reduction Methods in Volumetric Analysis, 191o). Salts of quadrivalent titanium are normally colourless, but the titanous salts, containing tervalent titanium, are generally violet or green, and include some power ful mordants which produce brilliant and stable colours, e.g., Ti2(SO4)3,Na2SO4,5H20. Hydrogen peroxide gives with titanium salts a yellow to brown coloration due to the formation of perti tanic acid, BIBLIOGRAPHY.—Titanium, publication 579 (1922), Department of Mines, Canada ; W. M. Thornton, Titanium (New York, 1927).
(W. WA.)