Titanium
2 of the 6 encyclopedias on this shelf carry an entry for Titanium. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a metallic element. The atomic weight is 48.0; the symbol, Ti. Titanium does not occur free. It was separated in 1791. It is a gray metallic powder not unlike iron in appearance. It occurs in many ores, rocks, clays, and other soils, as well as in meteorites. By means of the spectroscope we know that it exists in the sun. Titanium constitutes a considerable percentage of certain iron ores found in Canada, Sweden, and Norway. Certain ores of the Adirondack region run as high as fifty-three per cent of titanium and are in reality titanious ores containing iron. Titanium is added to iron and carbon in making steel rails, car wheels, and other steel articles requiring strength. In fact, the name titanium comes from the titans, the strong giants of the ancient mythology. Crystals of titanite, a composition of silicon, calcium, and titanium, are found in the limestones of St. Lawrence County, New York . A variety known as sphenes is cut for gems. The finest specimens come from Switzerland and the Tyrol.
Collier's New Encyclopedia (1921)
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.
What Has Changed in the Last Century
Collier's called titanium "a very rare metallic element" in 1921, and both accounts describe it only as a dark powder. It is in fact the ninth most abundant element in the Earth's crust; what was missing was a way to make it in bulk, since molten titanium grabs oxygen and nitrogen from the air. Matthew Hunter made ductile titanium in 1910 and William Kroll's magnesium-reduction process, patented in the 1930s and scaled up after 1945, turned it into a structural metal for jet engines, airframes, submarine hulls and hip and dental implants. Most titanium ore today never becomes metal at all: it is processed into titanium dioxide, the white pigment in paint, paper, sunscreen and toothpaste. The atomic weight is now 47.87, and the discovery is credited to William Gregor in 1791, with Klaproth supplying the name in 1795.
Written for this edition, 2026.