Titanium
a very rare metallic element, discovered by Gregor in 1789. Symbol Ti; at. wt. 50. It is never found in the metallic state, but may be obtained by heating the double fluoride of potassium and titanium with potassium in a covered crucible, or by mixing titanic oxide with one-sixth of its weight of charcoal and exposing to the strongest heat of an air furnace. It is a darkgreen, heavy, amorphous powder, having under the microscope the color and luster of iron. It dissolves in warm hydrochloric acid, with evolution of hydrogen, and, when heated in the air, burns with great splendor. Like tin, it forms two classes of compounds-the titanic, in which it is quadrivalent, and the titanous, in which it is trivalent. The spectroscope shows that there is titanium in the sun.