Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/547

 IVORY 523 from a tusk weighing 200 Ib the largest plaques he knows of could have been cut. Ivory can be made flexible by sub mitting it to the solvent action of phosphoric acid; when washed and dried it becomes hard, and when moistened again it resumes its flexibility ; but this is at the sacrifice of many of its properties. Ivory takes a variety of dyes well, without interfering with the polish of its surface ; the actual matrix is stained, and the colour is not merely due to the penetration of pigment into the open dentinal tubes. The great canine teeth of the hippopotamus furnish an ivory which is harder and whiter than that of the elephant, and less prone to turn yellow ; these differences are pro bably due to its containing a smaller percentage of organic matter. It also lacks the engine-turning pattern of elephant ivory. The tusk of the hippopotamus is a tooth of persistent growth, strongly curved into a segment of a circle, and solid in the greater part of its length. It is thickly coated with enamel on its exterior surface, and is trihedral, On transverse section the remains of the pulp cavity are seen as a line or fissure in the middle, and occasionally there is a nodule of secondary dentine in it. The ivory is not quite homogeneous ; for the back of the tooth, which is not covered with enamel and in use wears down the fastest so as to keep a sharp edge to the tusk, is markedly softer than the rest of the tooth. No large piece can be obtained from a hippopotamus tusk, and the incisors and the upper canines yield even smaller pieces than the lower canines. Thirty years ago there was a con siderable demand for them for dentists use, and at that time a fine tusk of 5 ft weight was worth from five to seven guineas, but the price is now much lower, and comparatively few are imported. Amongst the northern nations the tusks of the walrus have long been used as a source of ivory. The great upper canines consist of a body of dentine invested with cementum ; they are oval in section, solid, and their axis is made up of secondary dentine, which is far larger in amount than in the hippopotamus, and makes up a con siderable part of the whole tooth. This is very nodular in appearance when cut and polished, but is of dense and tolerably uniform consistence. The spirally twisted tusk of the narwhal, the teeth of the sperm whales, the ear bones of whales, and the molar teeth of the elephant, are also all made use of as sources of ivory, though they are far less valuable than the larger tusks. For the subject of carvings in ivory, see CARVING, vol. v. p. 167. The earliest piece of ivory work known is a rude incised drawing of a mammoth upon a fragment of mam moth tusk, which must have been executed by a contem porary of the animal. Numerous references to ivory occur in the Old Testament, which show that it was regarded as of great value. It seems to have been used for the decoration of the temple, and it is often mentioned amongst the presents brought to kings, who employed it for purposes of regal state. Some, however, of the references would seem more strictly applicable to wood than to ivory. The Nineveh ivories in the British Museum are of very great antiquity, a probable date of 900 B.C. having been assigned to them ; yet many of them are in good preserva tion, and others have been tolerably well. restored by boiling in gelatin. All exhibit considerable artistic merit and mastery over the material, whilst some reach a very high degree of excellence alike in design and execution. Competent judges declare that, underlying the obviously Egyptian character of the work, there are differences sufficient to lead to the inference that the ivories were not executed in that country. Some of them consist of thin plaques on which figures were delineated by means of incised lines ; some were carved in low, and others in high relief; whilst there are many examples of detached heads, and even entire figures, carved in close imitation of nature (see Plate VII.). Traces of gilding remain on many of them, and they were often further enriched by being inlaid with fragments of lapis lazuli, or of a coloured glass in apparent imitation of this : the eyes of the larger heads were generally rendered conspicuous by this means. In one of the panels figured, the border of the dresses, the thrones on which the figures are seated, the ornaments above the cartouche, and the symbols upon the cartouche itself were thus inlaid with colour. The largest object is a carved staff, perhaps a sceptre ; amongst the smaller pieces are heads of animals and entire animals, griffins, human heads, crossed and clasped hands, rings, &c. Like the ivory carvers of later times, these early workers seem to have studied economy of their material ; thus a beautiful carving in high relief of two griffins standing upon papyrus flowers has been carved on the interior of a segment of a large tusk, the natural curvature of which it follows. The tendency of ivory to decompose into concentric layers parallel with its exterior has been already noticed, and Mr Layard himself speaks of the trouble he experienced owing to the flaking of the pieces he discovered ; it is by the separation along the contour lines that many ancient ivories have been spoiled. Besides those discovered at Nineveh, some other ivories of great antiquity exist ; and ivory workers are mentioned as a distinct class of artificers at the commencement of the Christian era. Many writing tablets of ivory, with raised rims inside, where Wax was spread over their surface, have come down to us ; these were tfften made to fold together, and the exterior richly ornamented with carvings. It was the custom for newly appointed consuls under the empire to send these plaques to persons of importance, and the covers sometimes have upon them representations of the consul in his robes of office. One of the most beautiful of ancient ivories is the Roman 3d century plaque purchased by the South Kensington Museum for 400 (see Plate VII.). It forms one half of a diptych, and measures 11| by 4f inches. The other half is in the Hotel Cluny. From these times down to the present day there has been a constant succession of ivory workers, though in mediaeval times artists of higher ability were to be found than any who will now devote themselves to such work. A large proportion of the carvings deal with sacred sub jects : one of the most beautiful is a Pieta, the virgin holding the dead body of Christ in her lap (see Plate VII.) ; this was executed about the 14th century. Illustrations of old romances were frequently made use of to decorate mirror cases, boxes, etc., and elaborately carved chessmen of walrus ivory referable to an ancient period have been found in the island of Lewis. Schliemann, in his excava tion at the supposed site of Troy, found many useful articles made of ivory, pins, buckles, &c., but no carvings, even of rude character. Among the chryselephantine statues of ancient Greece executed by Phidias, Praxiteles, and others, one of Minerva in the Parthenon was 40 feet in height, and was con structed of ivory and gold ; others are mentioned as made of wood, with face, hands, and feet of ivory. Yet in some cases it is expressly said that the statue was entirely of ivory, special exception being made of a portion of the dress which was not. Among the Nineveh ivories are some which apparently belonged to figures partly wood arid partly ivory, but these were of no great size ; the wood employed seems to have been ebony. In former times ivory was frequently used for the manu facture of artificial teeth ; but this has become a thing of the past, ivory having been superseded by more durable and more manageable materials. Its use for this purpose