Ivory
2 of the 7 encyclopedias on this shelf carry an entry for Ivory. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a hard substance not unlike bone. The teeth of most animals are composed chiefly of ivory. Commercial ivory consists of the tusks of the elephant, the hippopotamus, walrus, narwhal, and a few other animals. An elephant's tusks are incisors. The large teeth of the hippopotamus and walrus are canines. The best ivory is obtained from elephant's tusks. The African elephant furnishes the best ivory known. The tusk of a large African elephant reaches an extreme length of nine feet and a weight of 260 pounds. Those of the Indian elephant average perhaps fifty pounds in weight. The tusks of the mammoth, an extinct elephant of Siberia, attained a length of twelve feet and a weight of 200 pounds. They are known in the trade as fossil ivory. The present supply of ivory comes from Siberia, India, and Africa. The Congo region, Abyssinia, Senegal, and Gaboon yield large amounts. All sources yield about 1,500,000 pounds a year. London, Antwerp, and New York are the leading centers of the ivory trade. An ivory auction is held at Antwerp four times a year. The average amount disposed of at one of these sales is about 130,000 pounds. The Antwerp price at a recent sale (1908) was from $4.65 to $5.35 per pound for sound tusks. The ivory auctions of London attract many buyers. As fast as the ivory comes in from Africa and India, it is displayed on the floor of a large ivory warehouse. The tusks are arranged in small lots. Here an enormous tusk lies alone; here half a dozen smaller ones; here a handful of fragments. The parcels are made up with a view to uniform quality. Sound white ivory is not mixed up with cracked or stained tusks. At regular intervals the lots are listed by number in a catalog. The sale is conducted like a book auction. Ivory is used for a variety of purposes. It is employed in expensive cabinet work. Many ornamental articles, such as knife handles and bangles, are made of ivory. The Chinese and the jewelers of India are skillful in carving images of ivory. Ivory is one of the most elastic substances known. If dropped on a hard surface, an ivory ball will bounce higher than a rubber ball. For this reason it is preferred for billiard balls. These balls are turned from the choicest parts of the tusks and must be kept in a room of uniform temperature for a few days to prevent checking. Ivory is becoming so scarce that a prime billiard ball is quoted at fourteen dollars, though formerly a set could be had for five dollars. No other substance has a touch at once so hard and so velvety. It is indispensable for the keys of high grade pianos. Bone, celluloid, and a palm nut known as vegetable ivory are substitutes, but they are not satisfactory. See Mastodon ; Elephant
Collier's New Encyclopedia (1921)
the osseous matter of the tusks of the elephant, and of the teeth or tusks of the hippopotamus, walrus, and narwhal. The ivory of the hippopotamus is preferred by the dentist, being free from grain and much harder and of a purer white than that of the elephant. The shavings and saw-dust of ivory may by burning be converted into a black powder, used in painting, named ivory black. Africa supplies the great bulk of ivory, the Indian wild elephant having become so scarce of late years that India is now obliged to import a considerable quantity of ivory. A vast amount of fossil ivory is also exported from eastern Siberia to various countries. African ivory fetches a higher price than any other, being dense in texture, susceptible of a higher polish and not so liable to turn yellow when exposed to the light as the Indian kind. The tusks of a full grown elephant seldom measure over six feet and weigh from 100 to 200 pounds. The tusk is usually solid for about half its length, the base being quite thin and, therefore, of little use for commercial purposes.