Ivory is the name properly given to the tusks of elephants, a material which consists of that modification of dentine or tooth-substance showing in transverse sections lines of different shades running in circular arcs, and forming by their decussation minute lozenge-shaped spaces. By this character, which is presented by every portion of any transverse section of an elephant's tusk, true ivory may be distinguished from every other kind of tooth-substance, and from bone and all artificial imitations of ivory. Although no other teeth except those of the elephant present this characteristic, many other animals, such as the walrus, narwhal, hippopotamus, sperm-whale, &c., possess teeth or tusks which from their large size and from their density can be used for many purposes in the arts for which true ivory is employed. A small proportion of the ivory of European commerce comes from Ceylon, India, Burma, Cochinchina, and the islands of the Eastern Archipelago; but the greater part of the produce of the East is used in the regions of its production. The bulk of the ivory sold in the markets of London, Liverpool, and Antwerp is from the African elephant, and it comes from the interior by nearly every outlet from that continent. A small amount of ivory, brittle in quality, is also obtained from northern Siberia under the name of fossil ivory, being the tusks of the extinct mammoth embedded in the frozen soil of the region. The ivory of the tusks of the African elephant is held in the highest estimation by the manufacturer, on account of its superior density and whiteness. The tusks are of all sizes up to about 180 lb., but examples have been recorded exceeding 200 lb. in weight.
The value of ivory is in proportion to the size and soundness of the tusks. For the purposes of sale they are graded as teeth weighing 60 lb. and upwards, next from 40 to 60 lb., and third between 20 and 40 lb. Below the weight of 20 lb. they are called scrivelloes, which are classed as hollows and solids. In consequence of its increasing scarcity by reason of the constantly-expanding demand for ivory, there has been a fluctuating but gradual rise in the price of the substance; but in recent years values have remained remarkably steady. Taking west coast African 'teeth' of good quality, the price may be said to have averaged £50 per cwt. during the ten years 1881-90, although according to quality it may range from £37 to £60 in a single sale; while from £50 to £60 may be taken as the price of good ivory in 1890. Selected teeth, and cuts made for special purposes, such as billiard ball solids, may command about £110 per cwt. The quantity annually imported into Europe averages 12,500 cwt., and in the East there is worked up about 2500 cwt. more, to procure which not fewer than 40,000 elephants must be sacrificed. Beyond this there must be many thousands of elephants killed every year in Africa to supply tusks for chiefs and head-men, which they use profusely for the ornamentation of their dwellings and graves. Ivory is conveyed to the coast by slave labour; and it has repeatedly been said that the extinction of the African elephant (which with the present enormous slaughter seems likely ere long to be achieved) would secure the suppression of the slave-trade. Among western communities ivory is chiefly in demand for knife and other handles, combs, piano keys, billiard balls, chess-men, and for carved figures and ornaments. Dieppe is the principal seat of the carved ivory trade; but nearly the half of the material used is worked up in England.
It has been assumed because of the large slabs of ivory used by ancient artists, some of which are still extant, that they possessed a method of softening, bending, and flattening the substance, the secret of which is now lost. One ancient author indeed mentions a means of softening and bending ivory by means of acid solutions, and various recipes are given by medieval writers for that purpose; but these are not found practicable. It is alleged that immersion in a solution of phosphoric acid renders ivory pliant and translucent; but that is done at the expense of its texture and elasticity—in short, such treatment deprives the substance of the very qualities which render it valuable.
The use of ivory can be traced almost to the earliest period at which there is evidence of the existence of man upon the earth. On fragments of mammoth tusks which have been picked up in the caves of Dordogne there have been found incised drawings of many animals, some now extinct and others no longer inhabiting Europe, executed with a spirit and fidelity which are simply marvellous. From that time downwards the records of every civilised community demonstrate the important value occupied by ivory, and the high commercial value it possessed. It was a substance distinctive of royal state and authority in ancient monarchies; and we read that King Solomon 'made a great throne of ivory.' There still exist examples of Egyptian inlaid ivory as ancient as the days of Moses, and Mr Layard in his Nineveh excavations secured many Assyrian ivory carvings, believed to date nearly 1000 B.C., which are now preserved in the British Museum. When culture and art were at their height in ancient Greece ivory was lavishly used for carvings, sculpture, and objects of luxury; and many of the greatest and most famous works of Phidias and his fellow-artists were 'Chryselephantine' (q.v.) statues—gigantic works built of plates of ivory and gold, some of the figures reaching a stature of 40 feet. Among the Romans the use of ivory for purposes of luxury was equally extensive; and by them plates of ivory, joined as diptychs or triptychs, were used as writing-tablets. Presents of such diptychs were commonly made by consuls on their appointment to officials within their jurisdiction, and among the treasures of classical times which yet exist are many remains of consular ivories. In the middle ages ivory came into use for ecclesiastical purposes in the form of tablets and diptychs for keeping registers and records, for crucifixes, statuettes of saints, caskets, reliquaries, croziers, book-covers, &c. At the same period for secular use it was carved into chess-men, mirror cases, combs, 'oliphants' (hunting and tenure horns), and numerous other forms.