Page:Encyclopædia Britannica, Ninth Edition, v. 12.djvu/861

Rh Choctaws, Chickasaws, and Seminoles, have made considerable advance in civilization. All the members of the above tribes wear the ordinary dress, live in houses, and are engaged in civilized pursuits. Their occupations are almost entirely farming and stock-raising, principally the former. They support schools, which are attended by a large proportion of the children of the tribes.

The following tables, taken from the report on Indian affairs for 1879, illustrate the progress made by these five tribes:—

Agricultural Products in 1879.

In 1878 there were 263,000 acres in the territory under cultivation by Indian labour; 503,000 bushels of wheat were produced, 3,038,000 of Indian corn, 220,000 of oats and barley, 339,000 of vegetables, and 120,000 tons of hay. The live stock consisted of 59,200 horses, 249,000 cattle, 189,400 swine, and 22,500 sheep.

The population of the five civilized tribes is almost entirely rural. There are no large towns. The principal settlements are Tahlequah, the capital of the Cherokee nation; Caddo in the Choctaw, Muscogee in the Creek, and Tishomingo in the Chickasaw country; and Vinita, a railroad town on the Missouri, Kansas, and Texas line.  INDIA-RUBBER, or, consists of the dried coagulated milky juice of various trees and shrubs, belonging chiefly to the natural orders Euphorbiaceæ, Moraceæ, Artocarpaceæ, and Apocynaceæ. Although a milky juice is found in plants of many other families, it does not in all cases yield caoutchouc, nor do different species of the same genus yield an equal quantity or quality of that substance. On the other hand, there are many plants which afford a good rubber, but have not yet been sought out for commercial purposes. The milky juice of plants furnishing caoutchouc is contained chiefly in the middle layer of the bark, in a network of minute tubes known to botanists as laticiferous vessels. In the Apocynaceæ these vessels are found also in the inner bark, or bast layer. The milky juice above mentioned possesses the properties of a vegetable emulsion, the caoutchouc being suspended in it in the form of minute transparent globules, averaging, according to Adriani, inch in diameter. Like other emulsions, it is easily coagulated by the addition of an acid or saline solution, alum or salt water being commonly used for this purpose; but it is said by Mr Bruce Warren not to be coagulated by alcohol. The caoutchouc appears to be kept in suspension in the juice by means of ammonia; at least in some cases the fresh milk exhales an ammoniacal odour. Probably it is on this account that the addition of liquid ammonia prevents the juice from coagulating for a considerable length of time; and the ammonia is in certain districts added when the milk has to be carried some distance from the place of collection. The addition of salt water to the juice is to be deprecated, as it renders the caoutchouc very hygroscopic. The best rubber known is obtained by careful evaporation of the recently strained juice at a moderate heat. Trees are known to contain caoutchouc by the bark on incision yielding a milk that when rubbed between the fingers coagulates into an elastic fibre. The dried bark of such plants when broken shows between the two fractured surfaces of bark a number of silky fibres which can be stretched for some distance without breaking.

Caoutchouc differs from other vegetable products of like origin by possessing considerable elasticity, by being insoluble in water or alcohol, alkalies, and acids (with the exception of concentrated nitric and sulphuric acids). Although apparently simple in constitution, it contains, not only the elastic substance to which its commercial value is due, but a small quantity of an oxidized viscid resinous body soluble in alcohol. This latter substance varies in quantity in different kinds of rubber, those containing the smallest amount, such as the Pará and Ceara, being considered the most valuable, while those in which it is present in greatest proportion, such as the Guatemala and African rubbers, are the least esteemed. Rapid evaporation of the juice, or any means which prevents oxidation, tends to prevent the formation of this viscid resin.

The first notice of india-rubber on record was given nearly five hundred years ago by Herrera, who, in the second voyage of Columbus, observed that the inhabitants of Hayti played a game with balls made "of the gum of a tree," and that the balls, although large, were lighter and bounced better than the wind-balls of Castile (Herrera, Historia, dec. i. lib. iii. cap. iv.). Torquemada, however, seems to have been the first to mention by name the tree yielding it. In his De la Monarquia Indiana, published at Madrid in 1615, tom, ii., cap. xliii. p. 663, he says, "There is a tree which the [Mexican] Indians call Ulequahuitl; it is held in great estimation and grows in the hot country. It is not a very high tree; the leaves are round and of an ashy colour. This tree yields a white milky substance, thick and gummy, and in great abundance." He further states that the juice was collected and allowed to settle in calabashes, and was afterwards softened in hot water, or the juice smeared over the body and rubbed off when sufficiently dry. The tree mentioned by Torquemada has usually been identified as Castilloa elastica, Cerv., but the above account cannot apply to it, as that tree is described by Cervantes as one of the loftiest forest trees of the north-east coast of Mexico, and its leaves are not round but oblong-lanceolate. Torquemada mentions also that an oil was extracted from the "ulli," or rubber, by heat, possessing soft and lubricous properties, and of especial effect in removing tightness of the chest. It was also drunk with cocoa to stop hæmorrhage. Even at that early date the Spaniards used the juice of the ulé tree to waterproof their cloaks. This fact, however, apparently did not attract attention in the Old World, and no rubber seems to have reached Europe until long afterwards. The first accurate information concerning any of the caoutchouc trees was furnished by La Condamine, who was sent in 1735 by the French Government to measure an arc of the meridian near Quito.

In 1751 the researches of M. Fresnau, an engineer residing in Guiana, were published by the French Academy, and in 1755 M. Aublet described the species yielding caoutchouc in French Guiana. Nevertheless india-rubber remained for some time unknown in England except as a curiosity, for Dr Priestley, in the preface to his work on perspective, called public attention to it as a novelty for erasing pencil marks, and states that it was sold in cubical pieces of inch for 3s. each. India-rubber was not known