474 IVORY published " The Trials of a Mind in its Progress to Catholicism " (London and Boston, 1854). After his return he became professor of rheto- ric in St. Joseph's theological seminary at Ford- ham, and lecturer on rhetoric and the English language in the convents of the Sacred Heart and the sisters of charity. His last years were devoted to establishing the protectories for des- titute Roman Catholic children at AVest Chester, N. Y., and to teaching in Manhattanville col- lege, New York, which he aided in founding. IVORY, the osseous substance which composes the tusk of the elephant, and which is a pecu- liar modification of dentine. In commerce it is customary to include in the term the tusks of the hippopotamus, the walrus, the narwhal, and some other animals; but according to Owen and other high authorities it can only be strictly applied to the peculiar reticulated modification in the elephant's tusk, although this is analo- gous to the substance (dentine) which forms the main part of all teeth. The appearance given by a cross section of any portion of an elephant's tusk, of circular lines intersecting each other so as to form lozenge-shaped figures with curved boundaries, distinguishes true ivo- ry from all other bony substances, and from all other tooth substances, whether dentine or not. The principal supplies of ivory are derived from the W. and E. coasts of Africa, the Cape of Good Hope, Ceylon, India, and the countries east- ward of the straits of Malacca. The best comes from Africa, and is of a finer texture and less liable to turn yellow than that brought from India. Prof. Owen says: "The African ele- phant, as is well known, is a distinct species from the Asiatic one ; and some of the Asiatic elephants of the larger islands of the Indian archipelago, as those of Sumatra, if not spe- cifically distinct from the elephants of con- tinental Asia, form at all events a strongly marked variety ;" and he remarks that in the Asiatic elephants tusks of a size which gives them the value of ivory in commerce are pecu- liar to the males, while in the African ele- phants both males and females afford good- sized tusks, although the males have the largest. The best tusks are nearly straight, and in sec- tion nearly circular. One of the largest has been found to measure 8J in. on its longer and 7 in. on its shorter diameter. They are hollow for about half their length, and a line is traced from the termination of the cavity to the tip of the tusk, which marks in the solid ivory the former extension of the cavity. Upon the outside they are coated with a rind one tenth to one fifth of an inch thick, the color of which in the African varieties may be one of numer- ous transparent tints of orange, brown, or al- most black, and in the Asiatic an opaque fawn or stone color. It conceals the quality of the ivory within, which may be partially exposed at the worn tip, but is finally ascertained only on the introduction of the saw by which the tusk is cut up for use. Even in the interior it is often found to be of variable character, opaque patches appearing in the transparent quality, and the white being sometimes marked in rings alternately light and dark colored. In the larger teeth the grain is often coarse in the outer portion, and becomes fine within; and some varieties are of chalky consistency like bone, and present dark brown spots. The qualities are so variable, that when exact matches are required of several articles it is important to cut them from the same tusk. The chemical composition of ivory is said to differ considerably in the animals of different countries ; but this probably depends upon the age of the animal and the part of the tusk from which the specimen is taken, although the kind of food will exercise an influence. The follow- ing analysis, taken from the Dictionnaire uni- versel, may be assumed as its average compo- sition: animal matter, dried, 24-00; water, 11'15; phosphate of lime, 64'00 ; carbonate of lime, O'lO. By very long exposure under fa- voring circumstances the animal matter be- comes dissipated, rendering the texture brit- tle. This was the condition of some ancient ivory carvings found by Layard in the ruins of Nineveh. To restore their tenacity Prof. Owen recommended boiling them in a solution of gelatine. The experiment proved perfect- ly successful, and the ivory thus regained its original strength and solidity. A remarkable source of ivory, which has long supplied the Russian markets, is the tusks of fossil mam- moths found in the banks of the rivers of northern Siberia. This fossil ivory is of simi- lar quality to that of living animals, and some of the tusks are of immense size. Iloltzapffel says he has seen tusks which were 10 ft. long and weighed 186 Ibs. They were solid from their tips to within 6 in. of the larger end, and the ivory was of fine grain and sound tex- ture. The uses of ivory are very numerous. It is exquisitely smooth in working, altogether devoid of the harsh meagre character of bone, and is in all respects the most suitable material for ornamental turning, as it is capable of re- ceiving the most delicate lines and cutting. The artists of Greece and Rome carved from the tusks of the elephant statues and various works of art, among which those of Phidias are especially famous. The size of some of the statues has led to the opinion that the ancients obtained larger tusks than those of modern times, or that they had a method of softening and flattening out the material, or built it up in plates around a central core. (See Qnatre- mere de Quincy's Le Jupiter olympien, ou Part de la sculpture antique, Paris, 1815.) Ivory was a favorite material for sculpture also in the middle ages, and many beautiful specimens then executed are preserved in mu- seums and private collections. Dieppe in Nor- mandy has been for two centuries the chief seat of this branch of art in modern times. The Chinese possess extraordinary skill in working ivory, carving out of a solid block a number of hollow balls one within another,
