Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/542

 520 I y A I V IVANOVO, or IVANOVO-VOZNESENSK, the &quot; Manchester of Russia,&quot; a town in the government of Vladimir, 20 miles north-west of Shua, near the river Uvod, and on the road from Shua to Nerakhta. It consists, as the full name implies, of what were originally two villages Ivanovo, which existed at least as early as the 16th century, and Voznesensk, of much more recent date united into a town in 1861. Of best note among the public buildings are the cathedral of the Elevation of the Cross, and the church of the Intercession of the Virgin, formerly asso ciated with an important monastery founded in 1579 and abandoned in 1754. One of the colleges of the town contains a public library. The industrial history of Ivanovo begins with the 18th century. Linen-weaving was introduced in 1751, and in 1776 the manufacture of chintzes was brought from Schliisselburg by some natives of the village. By 1850 the worth of the chintzes amounted to 6,680,875 roubles, and 10,000 workmen were employed in the manufacture of coarse calico. The reports of 1879 show 35 calico-print works, a wool-spinning factory, 6 cotton-weaving factories, 8 bleachworks, 6 iron works, 3 chemical works, and several minor establish ments. The workmen number about 15,000 or 20,000. The cotton factories produce to the annual value of 25,000,000 to 30,000,000 roubles; the iron works manu facture 110,000 poods (1770 tons) of iron, and there is a considerable turn out of boilers and factory machinery. Bast mats are made to the value of 15,000 roubles. IVORY is essentially equivalent to dentine, that hard substance, not wholly unlike bone, of which most teeth principally consist. By usage, however, its application has become almost restricted to the dentine of those teeth which are large enough to be available for industrial purposes, viz., the tusks of the elephant, the hippopotamus, the walrus, the narwhal, and the sperm whales. Ivory consists of an organic matrix or basis substance (which by prolonged boiling is converted into gelatin), per meated by an immense number of exceedingly fine canals. The matrix is richly impregnated with calcareous salts, which are probably held in some loose form of chemical combination with it, and is of such consistence that it retains its form after removal of the salts by an acid solvent. The canals start from the axial pulp cavity, and run in a direction generally outwards towards the periphery of the tusk ; in the elephant they are of exceptional fineness, being only about j^Vo of an inch in diameter, and are placed very closely, being separated by intervals not much greater than their own diameter. To the regularity with which the tubes are disposed, and to their small size and frequent curvature, ivory owes its fineness of grain, and probably also its almost perfect elasticity ; whilst to the peculiarities of their curvatures it owes that very charac teristic pattern of curved decussating lines, like engine turning, which is seen where the surface is a section transverse to the tusk. For, though it is broadly true that the tubes in elephant ivory run from the axis of the tusk to its periphery, they do not run straight, but make a suc cession of strong bends at regular intervals, and as the light 13 differently refracted by the basis substance and by the tubes according to the direction they are pursuing, this peculiarity of their course results in producing that pattern found in the dentine of FrobosciJea only. Ivory differs from bone in its finer structure and greater elasticity, and in the absence of those larger canals which convey blood vessels through the substance of bone, and appear upon it as specks or as stripes, according as it is cut transversely or longitudinally. Whan a transverse section of a tusk cut at a distance from the growing pulp is examined, its middle is seen to be occupied by a darkish spot of obviously different structure; this is the last remains of the pulp, rudely calcified. The outer border of the section consists of a thick layer of cementum, with which the whole tusk is coated, and the rest is ivory, showing the characteristic engine-turning pattern, and, in addition to this, numerous circular lines, concentric with the central spot. These &quot; contour &quot; lines are due to the occurrence of a large number of minute irregular spaces, found in all dentine, but specially abundant and disposed with a greater regu larity in ivory ; they are known as interglobular spaces, from the form of their boundaries when seen under a moderate magnifying power. In the areas occupied by these spaces there is a smaller proportion of lime salts and more organic matter ; consequently the ivory is here less dense and more liable to decomposition, and fossil tusks, as well as the less perfectly preserved of mammoth tusks, are frequently found to have broken up into a number of superposed cones, and in transverse section to present many concentric detached rings of ivory more or less friable. See Plate VII. Arguing from the analogy of other dentine, it cannot be doubted that the minute tubes and the interglobular spaces are not empty in living ivory, but that they contain pro toplasmic substance, though how far this may have perished or altered in that portion of the tusk which is extruded and far distant from the growing pulp can only be deter mined by observations at present wanting. According to Von Bibra s analyses, ivory contains as much as from 40 to 43 per cent, of organic matter, whereas human dentine contains only about 25 per cent. ; of fat it contains from 24 to 34 per cent. It differs from other dentines chiefly in its richness in organic constituents, in the fineness of its tubes, in their peculiarly curved course, and in the abun dance of interglobular spaces arranged in &quot; contour &quot; lines. The tusks of the elephant are a pair of upper incisor teeth, which may attain to an enormous development. The largest teeth were possessed by the extinct mammoths, of which tusks have been found in Siberia 12 feet and more in length, and weighing 200 Ib each. Holzapffel men tions one of very fine quality, that was cut up into piano keys in England, which weighed 186 ft&amp;gt;, Among recent elephants the African species possess the largest tusks, these attaining to a length of 9 or 10 feet and a weight of 160 Ib each, whilst the tusk of an Indian elephant which measured 8 feet in length and weighed 90 R) has been placed on record as exceptionally large. A pair of African ! tusks at the London exhibition of 1851 weighed 325 Ib, and measured 8 feet 6 inches in length and 22 inches in circumference ; but authorities acquainted with the African ivory districts give 20 to 50 K&amp;gt; as the average weight of tusks. In Africa both males and females are furnished with large tusks ; but in the Indian species a sexual difference exists, the tusks of the female projecting only a few inches from the gums, while even of the males by no means all are &quot;tuskers.&quot; Sanderson says that 10 per cent, of Indian male elephants have very small tusks, while in Ceylon only one in three hundred of the males is powerfully armed. The peculiarity is not always trans mitted, tuskless sires (&quot; mucknas&quot;) breeding &quot; tuskers,&quot; and vice versa. The importance of tusks as giving an advantage in combat to their possessors is sufficiently indicated by the dread of a &quot; tusker&quot; shown by other elephants less favoured. Tusks are often broken by fighting, and always show marks of considerable wear, while even captive elephants, with their shortened tusks, make great use of them for a variety of purposes : for example, an elephant will, when set to pull at a rope, take it between his molar teeth and pass it over one of his tusks to get a good purchase. Nothing but an extremely strong and elastic material such as ivory is could withstand the strains to which it is constantly exposed. Captive elephants have their tusks shortened, and the