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rubber

rubber

rubber Sentence Examples

  • They had the consistency of rubber mats.

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  • Inside the dairy she shucked her coat and rubber boots, slipping into a pair of western boots she always kept in the barn.

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  • Inside the dairy she shucked her coat and rubber boots, slipping into a pair of western boots she always kept in the barn.

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  • Modern Plymouth has varied and important manufactures comprising cordage, woollens, rubber goods, &c. In 1905 the total value of the factory products was $11,115,713, the worsted goods and cordage constituting about nine-tenths of the whole product.

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  • Great developments have been made of recent years in the cultivation of rubber in British Malaya.

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  • The forest products of the state include fine woods, rubber, ipecacuanha, sarsaparilla, jaborandi, vanilla and copaiba.

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  • Want me to get the rubber hose from the car?

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  • (1882); On the Laticiferous Tissue of Man-rhot Glazsovii (the Ceark Rubber), Quart.

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  • From mining the clay to make the lead, to the lacquer applied to the pencil, to the rubber eraser, to the metal band holding the eraser to the yellow paint, no one person knows how to make a complete pencil.

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  • What we need to make its parts—iron ore to make steel, rubber to make tires, sand to make glass, petroleum to make plastics—is generally a few cents' worth of raw materials.

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  • The cost derives from the application of huge amounts of energy, intelligence, and technology to obtain and process the raw materials: digging and smelting to create high-grade steel, harvesting and refining and molding to make rubber parts, and so on.

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  • The exports include hides, skins, rubber, wax, tobacco and cotton.

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  • The pipes have specially shaped ends between which a rubber collar is placed, the joint being held together by clips.

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  • There are about twenty-two different trees, shrubs and vines producing rubber of more or less good quality.

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  • There are about twenty-two different trees, shrubs and vines producing rubber of more or less good quality.

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  • Its chief exports are rubber, gum, coffee and copper.

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  • Rubber factories 9,000 2 000

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  • In 1899 the Bolivian government established a custom-house at Puerto Alonso, on the Acre river, for the collection of export duties on rubber, which precipitated a conflict with the Brazilian settlers and finally brought about a boundary dispute between the two republics.

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  • The exports are chiefly groundnuts, rubber of inferior quality, sesamum and other oil seeds, tortoise-shell and ebony.

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  • He retrieved a jar from the small refrigerator and laid it next to a surgical knife, a large rubber tube, and a huge syringe.

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  • Across the room, Darkyn held the tension of a taut rubber band.

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  • The soil is fertile and produces rubber, cotton, sugar, coffee, cocoa, tobacco and nutmegs, all of which are exported; pimento (allspice) grows wild in the greatest profusion.

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  • Rubber and some other natural products are exported.

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  • Rubber and some other natural products are exported.

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  • Among economic plants should be mentioned the coffee, cacao, citron, cinnamon, cocoanut and rubber tree.

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  • The region, which abounds in valuable rubber forests, was settled by Bolivians between 1870 and 1878, but was invaded by Brazilian rubber collectors during the next decade and became tributary to the rubber markets of Manaos and Para.

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  • In calling upon dangerous blacks at night they pretended to be the spirits of dead Confederates, "just from Hell," and to quench their thirst would pretend to drink gallons of water which was poured into rubber sacks concealed under their robes.

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  • She pointed to the two young men, almost unrecognizable in their ponderous gear of boots, rubber coat, and visored helmet.

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  • There are large slaughtering establishments, and factories for the refining of sugar and for the manufacture of tobacco goods, soap and perfumery, lead pencils, iron and steel, railway cars, chemicals, rubber goods, silk goods, dressed lumber, and malt liquors.

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  • Ivory, rubber and copal are the chief exports.

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  • Other leading manufactures are malt liquors ($21,620,794 in 1905), railway rolling-stock consisting largely of cars ($21,428,227), men's clothing ($18,496,173), planing mill products ($17,725,711), carriages and wagons ($16,096,125), distilled liquors ($15,976,523), rubber and elastic goods ($15,963,603), furniture ($13,322,608), cigars and cigarettes ($13,241,230), agricultural implements ($12,891,197), women's clothing ($12,803582), lumber and timber products ($12,567,992), soap and candles.

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  • Other leading manufactures are malt liquors ($21,620,794 in 1905), railway rolling-stock consisting largely of cars ($21,428,227), men's clothing ($18,496,173), planing mill products ($17,725,711), carriages and wagons ($16,096,125), distilled liquors ($15,976,523), rubber and elastic goods ($15,963,603), furniture ($13,322,608), cigars and cigarettes ($13,241,230), agricultural implements ($12,891,197), women's clothing ($12,803582), lumber and timber products ($12,567,992), soap and candles.

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  • The principal jungle products are gutta and rubber of several varieties, and many kinds of rattan.

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  • Forest products include rubber, carnauba wax and dyewoods.

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  • Most of the automobiles are manufactured in Cleveland; most of the cash registers and calculating machines in Dayton; most of the rubber and elastic goods in Akron; nearly one-half of the liquors and about three-fourths of the men's clothing in Cincinnati.

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  • She clamped a rubber booted foot over a new knothole in the floor.

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  • Among the leading and more distinctive items were printing and publishing ($21,023,855 in 1905); sugar and molasses refining ($ 1 5,74 6, 547 in 1900; figures not published in 1905 because of the industry being in the hands of a single owner); men's clothing (in 1900, $8,609,475, in 1905, $11,246,004); women's clothing (in 1900, $3,258,483, in 1905, $5,705,470); boots and shoes (in 1900, $3,882,655, in 1905, $5,575,927); boot and shoe cut stock (in 1905, $5, 211, 445); malt liquors (in 1900, $7,518,668, in 1905, $6,715,215); confectionery (in 1900, $4,455,184, in 1905, $6,210,023); tobacco products (in 1900, $3,504,603, in 1905, $4,59 2, 698); pianos and organs ($3,670,771 in 1905); other musical instruments and materials (in 1905, $231,780); rubber and elastic goods (in 1900, $3,139,783, in 1905, $2,887,323); steam fittings and heating apparatus (in 1900, $2,876,327, in 1905, $3,354, 020); bottling, furniture, &c. Art tiles and pottery are manufactured in Chelsea.

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  • She clamped a rubber booted foot over a new knothole in the floor.

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  • The natural products include fine cabinet and construction woods, rubber, fruit, palm oil and fibres.

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  • If, however, the precipitate refuses to settle, it is directly transferred to the filter paper, the last traces being removed by washing and rubbing the sides of the vessel with a piece of rubber, and the liquid is allowed to drain through.

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  • The rubber trade is controlled by the Liberian Rubber Corporation, which holds a special concession from the Liberian government for a number of years, and is charged with the preservation of the forests.

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  • Donning a heavy coat and some rubber boots that she found in the entry closet, she battled the storm to the shed.

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  • In the rubber ring joint an india-rubber ring is used; slightly less in diameter than the pipe.

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  • There are considerable forests of oil palms, rubber trees and vines, and timber and dyewood trees.

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  • The chief trade is in, and the principal exports are, palm oil and kernels, rubber, cotton, maize, groundnuts (Arachis), shea-butter from the Bassia parkii (Sapotaceae), fibres of the Raphia vinifera, and the Sansevieria guineensis, indigo, and kola nuts, ebony and other valuable wood.

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  • Resting on the centre of the ivory disk was a small piece of rubber tubing, and this was lightly pressed by the diaphragm A, which was held in place by the mouthpiece M.

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  • She staggered on legs of rubber and he lifted her to the counter, sitting her in front of him.

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  • Among the imported flora are tea, Siberian coffee, cocoa, Ceara rubber (which has not done well), Manila hemp, teak, cocoanut and a number of ornamental trees, fruit-trees, vegetables and garden plants.

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  • Mangabeira rubber is collected to a limited extent, and piassava fibre is an article of export.

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  • Sulphur chloride dissolves sulphur with great readiness and is consequently used largely for vulcanizing rubber; it also dissolves chlorine.

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  • The Nidi forest is noteworthy for its magnificent growth of Funtumia rubber trees.

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  • This Strophanthus is not remarkable for its rubber - which is mere bird lime - but for the powerful poison of its seeds, often used for poisoning arrows, but of late much in use as a drug for treating diseases of the heart.

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  • Among the manufactures are charcoal, pig-iron, car wheels and general castings at Lime Rock, cutlery at Lakeville, and knife-handles and rubber brushes at Salisbury.

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  • Figures with rubber gloves were turning him over.

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  • A great variety of industries is carried on, the chief being the manufacture of semolina and other farinaceous foods, confectionery, preserved fruit and jams, chemicals and rubber goods.

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  • The rubber is circular in section, and about 2 in.

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  • The value of the city's factory products in 1905 was $13,879,159, the principal items being rubber and elastic goods ($3,635,211) and boots and shoes ($2,044,250) The manufacture of stoves, and of mucilage and paste are important industries.

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  • He helped her up and she tried to stand, but her legs felt like rubber.

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  • A million little diamonds of glass showered the inside of the vehicle as it swerved up the street, spinning a track of rubber.

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  • The trees are regularly tapped and the coagulated latex which exudes is collected and worked up into rubber.

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  • Amongst arboreous families Leguminosae and Euphorbiaceae are prominent; Hevea belonging to the latter is widely distributed in various species in the Amazon basin, and yields Para and other kinds of rubber.

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  • The cultivated trees and plants of importance are, besides rubber, the manioc or cassada, the orange tree, lime, cacao, coffee, pineapple (which now runs wild over the whole of Liberia), sour sop, ginger, papaw, alligator apple, avocado pear, okro, cotton (Gossypium peruvianum - the kidney cotton), indigo, sweet potato, capsicum (chillie), bread-fruit, arrowroot (Maranta), banana, yam, "coco"-yam (Colocasia antiquorum, var.

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  • RUBBER, INDIARUBBER or Caoutchouc (a word probably derived from Cahucha or Gaucho the names in Ecuador and Peru respectively for rubber or the tree producing it), the chief constituent of the coagulated milky juice or latex furnished by a number of different trees, shrubs and vines.

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  • The latex of the best rubber plants furnishes from 20 to 50% of rubber.

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  • There is, however, reason to believe that the coagulation of latex into rubber is not mainly of this character.

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  • The existence of caoutchouc or rubber was first observed soon after the discovery of America.

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  • La Condamine ascertained the nature of the tree, now known as Hevea brasiliensis, from which the Para rubber of S.

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  • America was obtained, whilst a little later Fresnau and Aublet described the Euphorbiaceous trees which furnished the rubber of Guiana.

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  • America and in Mexico for incising the trees and obtaining the rubber are exceedingly primitive, but survive with little modification at the present day.

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  • Until recently rubber was obtained almost exclusively from the tropical forests of S.

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  • The increase in the demand, for which the employment of rubber tires is largely responsible, has given an increased stimulus to the production of " wild " rubber, with the result that trees and vines have been recklessly cut and destroyed, and in some instances vast regions, as in the S.

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  • Sudan, have been nearly entirely denuded of rubber vines.

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  • Africa, can, however, only be enforced by special administrative machinery and at considerable expense, and this legislative action can only be regarded as temporary and preliminary to the establishment of plantations of rubber trees, which are not only easier to control, but the trees are less liable to injury from careless tapping.

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  • In Africa it seems probable that the production of rubber from vines is likely to be entirely superseded in process of time, and replaced by the plantations of trees which are already being established in those districts in which careful experiment has determined the kind of rubber tree best adapted to the locality.

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  • The wild rubber of S.

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  • and Central America is still the principal source of the rubber supply of the world, and is likely to continue to be so for many years to come.

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  • The enormous increase in the commercial demand for rubber and the probability of the continuance of this increase in view of the great variety of purposes to which the material can be applied, has led to great activity in rubber planting in other parts of the world, especially in Ceylon and the Malay Peninsula and Archipelago, where the Para rubber trees (Hevea brasiliensis) has been successfully introduced, and numerous plantations; many of which have not been in existence for more than ten or fifteen years, are now contributing to the world's supply.

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  • " Plantation " Para rubber from Ceylon and the Malay States has brought prices equal to and often exceeding those of fine Para rubber from Brazil.

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  • This is largely due to the improved methods of preparing the rubber practised by the planters of Ceylon and Malaya, which lead to the exclusion of the impurities usually found in " wild " rubber.

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  • Para rubber from Brazil generally contains about 15% of water, whilst " plantation " Para is usually nearly dry and contains 1% of water or less.

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  • It would appear, however, that the finest " wild " Para rubber as a rule possesses greater tensile strength than the " plantation " rubber.

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  • This has been ascribed by some to the presence in " wild " rubber of certain impurities derived either from the latex or introduced during the preparation of the rubber which are thought to enhance the physical properties of the caoutchouc. It is more probable, however,.

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  • that the superiority of the " wild " Para is principally due to the greater age of the forest trees from which the rubber is obtained, many of which are from thirty to fifty years old.

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  • known that the Hevea tree usually furnishes very inferior rubber if tapped before it is six or seven years old, and there is evidence to show that the quality of the rubber improves with the age of the tree.

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  • inferior rubber.

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  • It is therefore to be expected that as time goes on the quality of " plantation " rubber will improve, and there would seem to be no reason why it should not eventually be fully equal to that of the " wild " rubber.

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  • In 1909 the total production of rubber is stated to have been about 70,000 tons, of which more than one-half came from tropical America, about one-third from Africa, whilst the remainder was chiefly of Asiatic origin, including " plantation " rubber from Ceylon and Malaya, which amounted to about 3000 tons.

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  • Chiefly owing to the supplies of " wild " rubber which are: still available, comparatively little has been done until recently in establishing plantations either in Africa or in tropical America, but in Asia, including Ceylon, India and Malaya, in which.

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  • there are relatively few important naturally-occurring rubber plants, there has been for some years great activity in forming plantations of rubber trees introduced mainly from tropical America, and there are now many millions sterling of British capital invested in companies established to form rubber plantations chiefly in Ceylon and Malaya.

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  • Each year should therefore show an increase in the production of plantation rubber.

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  • Among these are the precise extent of demand, the limit of the inevitable fall in price with largely increased production, the cost of labour as increasing amounts are required, and the effect of changed conditions on the output of " wild " rubber and the competition of the new plantations which are being established in tropical America.

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  • There can be little doubt that with a fall in price further uses for rubber would arise, leading to an increased demand, and among them may be mentioned its utilization as a road material.

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  • i i.--Para Rubber Plantation, Ceylon.

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  • - Para Rubber Trees, Tapped - Ceylon.

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  • 13.-Ceara Rubber Tree.

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  • 14.- Castilloa Rubber Trees.

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  • The cost of collecting " wild " rubber is less easy to state with any approach to accuracy, since the cost varies in different districts of S.

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  • In Africa the cost of collection is much less, but the rubber is generally of inferior quality.

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  • The market price of commercial rubber is determined by the current price of " fine Para " from S.

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  • Having regard to the present cost of producing " plantation " rubber, and to the probability that, apart from a possible increase in the price of labour, this cost is susceptible of further reduction, it may be concluded that rubber production will continue to be profitable even should a considerable fall in market value take place.

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  • Most commercial rubber is derived from natural supplies, from the wild rubber trees of S.

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  • Each year, however, the output of " plantation " rubber will show a considerable increase, and it is to be expected that ultimately this will form the chief source of supply, unless unforeseen circumstances should arise to interfere with the development of the plantation industry, which has been vigorously started chiefly with European capital in the tropical possessions of Great Britain, France and Germany.

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  • The best rubber is now obtained from large trees, of which the following are the more important: I.

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  • " Para " rubber, which takes the first position in the market, is derived from species of Hevea, principally Hevea brasiliensis, of which there are enormous forests in the valleys of the Amazon and its tributaries, and also in Peru, Bolivia, Venezuela and Guiana.

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  • In Brazil alone it is stated that the rubber area amounts to at least one million sq.

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  • " Ceara " or Manigoba rubber is derived from species of Manihot, chiefly Manihot Glaziovii, a native of S.

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  • Partly for this reason and partly because pieces of wood and dirt are apt to be included with the scrap, the market value of Ceara rubber is usually less than that of Para.

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  • India have, however, begun to furnish a better quality of Ceara rubber, which is often prepared in biscuit form.

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  • The " Ule " rubber of Central America and British Honduras originates from Castilloa elastica.

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  • The rubber comes into commerce in thick strips or sheets or as " scrap."

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  • The rubber is usually dark in colour and is often contaminated with proteid impurities derived from the latex.

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  • Ule rubber is generally inferior in strength to Para and commands a lower price.

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  • America which furnish rubber of secondary commercial importance are Hancornia speciosa, yielding the Mangabeira rubber of Brazil, and species of Sapium furnishing the Colombian rubber and much of the rubber of Guiana (derived from Sapium Jenmani), which is scarcely inferior to the rubber of Para.

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  • " Rambong " or Assam rubber is the produce of Ficus elastica, commonly known as the indiarubber tree and cultivated in Europe as an ornamental plant.

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  • Although intrinsically of excellent quality, Rambong rubber, owing to the careless method of collection practised by the natives which leads to the inclusion of much impurity, usually fetches a lower price than Para.

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  • Africa and Egypt, but has not proved very successful in Africa as a rubber producer.

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  • " Lagos " rubber is the produce of the African rubber tree Funtumia elastica, which is indigenous to Africa from Uganda to W.

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  • It is known as the silk rubber tree, probably on account of the silky hairs which are attached to the seeds.

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  • The rubber is of good quality, though, owing to the method of preparation adopted, the product is often impure and discoloured, and consequently usually brings a lower price than the best rubbers of commerce.

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  • Besides the trees described above, a number of climbing plants or vines belonging to the Apocyanaceae secrete a latex which furnishes rubber of good quality.

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  • These vines are less satisfactory than trees as rubber producers, owing to the readiness with which they are injured and destroyed by careless tapping, and to the difficulty of regulating these methods in the case of vines distributed over enormous areas of forest.

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  • The rubber is obtained by incising the stems of the vines and coagulating the latex by exposure, by admixture with acid vegetable juices or by heating.

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  • Africa also furnish good rubber, as do the Forsteronia gracilis of British Guiana and Forsteronia floribunda of Jamaica.

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  • Among these are species of Willughbeia and Leuconotis, from which much of the rubber exported from Borneo is derived; Parameria glandulifera, common in Siam and Borneo, and Urceola esculenta and Cryptostegia grandiflora, both common in Burma.

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  • Among other sources from which rubber is commercially obtained may be mentioned the Guayule plant (Parthenium argentatum) of Mexico, and the "Ecanda " plant of Portuguese W.

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  • Africa, from the tuberous roots of which rubber is extracted by the natives.

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  • The root rubber prepared by the natives of the Congo and the S.

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  • It is obtained by breaking up the roots or rhizomes in hot water and separating the rubber, and machines have now been devised for this purpose.

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  • Little is at present known of the large rubber tree of Tonkin (Bleckrodea tonkinensis), the latex of which is stated to furnish excellent rubber.

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  • Sources Of Commercial Rubber I.

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  • Para Rubber is so named from the Para province of Brazil, from the principal town of which, also known as Para, most of the rubber is shipped.

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  • This rubber is obtained chiefly from Hevea brasiliensis, Mull.

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  • The genus Hevea was formerly called Siphonia, and the tree named Pao de Xerringa by the Portuguese, from the use by the Omaqua Indians of squirts or syringes made from a piece of pipe inserted in a hollow flask-shaped ball of rubber.

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  • The trees are not generally tapped until they are ten to fifteen years old, as young trees yield inferior rubber.

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  • The latex usually furnished about 30% of rubber.

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  • To obtain the rubber, the latex is usually treated in the following manner.

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  • The creosote and other products from the smoke no doubt act antiseptically and prevent to a large extent the subsequent putrefaction of the proteids retained by the coagulated rubber.

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  • Each layer of rubber is allowed to become firm before forming another; a practised hand can make 5 or 6 lb in an hour.

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  • In some districts a stout stick is substituted for the paddle, on which the rubber as it coagulates is wound cylindrically.

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  • The rubber thus prepared is the finest that can be obtained.

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  • The flat rounded cakes of rubber made in this manner are known in the London market as " biscuits.

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  • The yield of rubber varies, but it is stated on an average to be Io lb of rubber per tree, and if carefully tapped one tree will yield this amount for many years in succession.

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  • Ever since plantations of Hevea have been made on an increasing scale in the Straits Settlements, the Federated Malay States and in Ceylon, and at the present time rubber plantations form the principal industry in these colonies.

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  • A large number of plantations in British Malaya and Ceylon are now actively exporting increasing quantities of rubber.

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  • It may be estimated that between one and two million acres of land in the different countries referred to have been already appropriated for rubber plantations.

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  • In many plantations besides catch crops (cassava, sesame, ground-nuts, &c.) other crops, such as tea, coffee, cocoa and tobacco, are grown with rubber.

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  • It is improbable, except in the early stages of the rubber tree, that this procedure will succeed; the rubber will ultimately dominate the position to the detriment and ultimate extinction of the other crop, whilst the growth of the rubber tree will be retarded.

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  • The experience of planters in general is in favour of the complete removal of weeds from a rubber plantation.

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  • These disadvantages are at their maximum when the rubber trees are quite young.

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  • Another disadvantage of uncovered soil in a plantation of young rubber trees is that the ground under the heat of a tropical sun rapidly loses its moisture.

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  • One of the most important subjects in connexion with rubber plantations is the method to be adopted in tapping the trees for latex.

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  • from the base - that is, within the reach of an ordinary man without the need for ladder or scaffolding; the latex obtained from the upper part of the tree is said to furnish less rubber FIG.

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  • As a rule, an annual yield of more than 1-2 lb of rubber per tree must not be looked for from recent plantations, although much higher yields up to 10-15 lb and over per tree are recorded from S.

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  • An average of 150 trees to the acre (20X15 ft.) and a yield of 12 lb of rubber per annum per tree at 2s.

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  • The cost of clearing forest land and planting with rubber in Ceylon is estimated at about 100 Rs.

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  • The point of next importance is the coagulation of the latex so as to produce rubber in the form and of the quality required by the manufacturer.

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  • It is, however, important to remember that rough as these native methods are they result in the production of rubber which commands the highest price.

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  • The coagulated rubber separates as a mass of spongy caoutchouc. If the coagulation has been effected in shallow dishes, the rubber is obtained in a thin cake of similar shape known as a " biscuit."

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  • The rubber thus formed is washed and dried.

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  • The coagulated rubber separated from the watery fluid is cut up into small pieces and passed through the grooved rollers of the washing machine, from which it issues in sheets, long crinkled ribbons or " crepe," which are then dried in hot air chambers or in a vacuum dryer, by which means the water is dissipated at a lower temperature.

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  • In order to prevent decomposition of any proteid impurity which may remain incorporated with the rubber, the freshly coagulated rubber is sometimes cured in the smoke of burning wood or a small quantity of an antiseptic such as creosote is added during coagulation.

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  • Plantation rubber comes into commerce in the form of the crinkled ribbons known as crepe, in sheets or biscuits, and sometimes in large blocks made by compressing the crepe rubber.

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  • Block rubber is considered to possess certain advantages in securing a constant proportion of water, and in being satisfactory for transport.

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  • The best condition and form in which to export rubber cannot be regarded as settled.

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  • The probabilities are that in the end the production of a rubber as nearly as possible free from water and impurities and of constant composition will be realized as best meeting the requirements of the modern manufacturer.

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  • In the present transition stage of rubber production it is necessary for the manufacturer in Europe to wash all rubber.

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  • He receives both the wild rubber containing variable quantities of impurity and the purer plantation rubber, the latter, however, in much smaller amount.

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  • As soon as the output of plantation rubber of constant composition has reached much larger dimensions it is probable that the manufacturer will be able to dispense with washing.

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  • This will operate to the advantage of plantation rubber and against the wild rubber, so long as the latter is not exported in a purer condition.

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  • The mode of collecting the rubber is as follows.

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  • Ceara rubber is also exported in the form of lumps and cakes.

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  • The annual yield of rubber is rather more than 1 lb per tree.

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  • The latex coagulates readily, especially if churned or if diluted with water, when a purer rubber is obtained.

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  • Africa the tree flourishes, but it is under trial as a rubber producer.

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  • The pure Ceara rubber, as for example the " biscuits " prepared in Ceylon, is of excellent quality, scarcely if at all inferior to Para.

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  • The cultivation and collection of the rubber being troublesome, it is unlikely to be attended to in those countries in which Hevea is successful.

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  • The source of " Ule " rubber exported from Central America, and of the " Caucho " rubber of Peru is Castilloa elastica, Cerv., a lofty tree, N.

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  • in diameter, is expected to yield annually 20 gallons of milk, each gallon giving about 2 lb of rubber.

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  • The loss of Nicaragua rubber in drying is estimated at 15%.

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  • The Castilloa tree appears to be suitable for cultivation only in districts where the Para rubber would grow equally well.

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  • The tree is ready for tapping at about the same age as Hevea and the average yield of rubber is about the same.

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  • Since the latex " creams " readily the rubber can be separated from the latex by centrifugalizing, and its quality and market value thus enhanced.

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  • Much of the native Castilloa rubber is of inferior quality.

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  • Several other species of Castilloa than C. elastica are known to furnish rubber, but little has been recorded as to their advantages.

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  • African (Ire or Irai or Lagos) rubber tree, which belongs to the Apocynaceae, a natural order which includes the Landolphia vines as well as other rubber producers.

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  • African native name for a rubber tree - " Funtum."

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  • The watery portion of the latex soaks into the trunk, and the soft spongy rubber which remains is kneaded and pressed into lumps or balls.

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  • In some districts the collected milk is heated alone or diluted with water, to coagulate the rubber, but if heated alone an inferior rubber is apt to result owing to overheating.

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  • - Funtumia elastica (Lagos rubber).

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  • The yield of rubber is stated as a rule to be less than that of Para.

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  • The rubber, if properly prepared, is of excellent quality, and the tree deserves further attention, especially in those regions of W.

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  • Funtumia africana furnishes a very inferior rubber, which is highly resinous.

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  • Ficus elastica is the tree which produces Rambong or Assam rubber.

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  • size); of the rubber ex1 ported is still ob2, section of inflorescence (2 nat.

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  • It has been found that although the tree grows well in many different countries and different localities, it only furnishes a satisfactory yield of rubber in mountainous districts, such as those of Assam and certain parts of Ceylon and Java.

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  • The trees are tapped when about ten years old, and as a rule annually furnish from 5-10 lb of rubber per tree.

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  • The rubber, if of good quality, sells at prices only slightly inferior to that of Para.

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  • In addition to the trees described above there are numerous plants of some importance as rubber producers.

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  • Among these may be mentioned the Landolphia vines, which are still the chief source of African rubber.

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  • Africa, furnish rubber of inferior quality.

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  • Among other shrubs and vines which yield rubber of fair quality may be mentioned Willughbeia edulis and Urceola elastica and Parameria glandulifera, which occur in Burma and Malaya.

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  • The Sapiums of Colombia and Guiana are large trees resembling Hevea, and certain species furnish good rubber, especially the Sapium Jenmani of Guiana.

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  • brasiliensis, which are known to produce good rubber in tropical America.

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  • Pernambuco or Mangabeira rubber is obtained from Hancornia speciosa, Gom., an apocynaceous tree common on the S.

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  • It is about the size of an ordinary apple tree, with small leaves like the willow, and a drooping habit like a weeping birch, and has an edible fruit like a yellow plum called " mangaba," for which, rather than for the rubber, the tree is cultivated in some districts.

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  • Only a small quantity of this rubber comes to England, and it is not much valued, being a " wet " rubber.

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  • In two or three minutes coagulation takes place, and the rubber is then exposed to the air on sticks, and allowed to drain for eight days.

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  • Pernambuco rubber, as is the case with most rubbers coagulated by saline solutions, contains a large quantity of water.

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  • Like the Forsteronia floribunda of Jamaica it yields rubber of good quality.

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  • Africa yields rubber of variable quality.

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  • The production of rubber by this tree merits further investigation, as it grows readily in nearly every district of W.

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  • Chemistry of Rubber.

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  • Rubber is chiefly composed of the soft, solid, elastic substance known as caoutchouc. It is usually assumed that this substance is present as such in the latex.

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  • The watery liquid known as rubber milk or latex is an emulsion consisting chiefly of a weak watery solution of proteids, carbohydrates and salts holding the liquid globules in suspension.

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  • In connexion with the production of rubber the most important factor is the proportion of caoutchouc it contains.

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  • In a good rubber this ranges from 70-90% and over.

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  • The proteids should be as far as possible removed during the preparation of the rubber, as these substances are chiefly responsible for the objectionable smell and colour of " native " rubbers, and their presence leads to subsequent change in the commercial material.

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  • All crude rubber contains more or less proteid, and in the opinion of some technical experts its presence even affords strength to the material, but this cannot be accepted as proved.

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  • The dissolved salts (potassium, sodium, ammonium, calcium, magnesium, &c.) of the latex are generally nearly entirely absent from the wellprepared rubber.

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  • Of considerable importance to the value of the rubber is the absence of the resinous constituents which are present in greater or smaller proportion in all latices.

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  • The presence of more than a small percentage of resin in the latex leads to the production of rubber containing much resin, which seriously depreciates its commercial value for most purposes.

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  • The percentage of resin in a good rubber should be as small as possible, and should in any case be less than to %.

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  • There is no feasible method at present known of preventing the inclusion of the resin of the latex with the rubber during coagulation, and although the separation of the resin from the solid caoutchouc by means of solvents is possible, it is not practicable or profitable commercially.

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  • RUBBERS Para Ceara Castilloa Ficus Landolphia Para Latex Rubber Rubber Rubber Elastica Kirkii (Ceylon).

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  • The chemical analysis of crude rubber is an important guide to its value.

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  • At present, however, the methods of analysis usually employed are not sufficiently delicate to afford all the necessary information as to the intrinsic value of the higher grades of rubber, and do not go much beyond the exclusion of inferior rubber.

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  • The tests of the physical properties of crude rubber usually applied to determine its value in the market are also very rough and cannot be relied upon.

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  • The development of the rubber industry has now reached a stage at which more exact methods of determining the chemical composition and physical properties (strength and elasticity) of rubber are required.

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  • At present the caoutchouc present in crude rubber is usually estimated indirectly, and it is possible that what generally passes as caoutchouc may be in some instances a mixture of similar chemical substances, which if separated would be found to differ in those physical properties on which the technical value of rubber depends.

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  • It may therefore be said that caoutchouc has been already artificially or synthetically prepared, and the possibility of producing synthetic rubber cheaply on a commercial scale remains the only problem.

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  • At present the change of isoprene into caoutchouc is mainly of scientific interest in indicating possibilities with regard to the conversion of the liquid globules of the latex into rubber and to the formation of rubber by plants.

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  • The question as to whether synthetic rubber will ever be produced cheaply on a commerical scale is therefore the important one for those who are largely interested in the rubber-planting industry.

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  • Its settlement will depend in part on the cost of producing rubber from plants, which from their point of view it is to the interests of planters to reduce as far as possible.

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  • The best solvents for rubber are carbon bisulphide, benzol and mineral naphtha, carbon tetrachloride and chloroform.

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  • These liquids, either alone or mixed, are employed in making the rubber solutions used for technical purposes.

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  • Sulphur when warmed with caoutchouc combines with it, and on this fact the vulcanization of rubber depends, and also the production, with an excess of sulphur, of the hard black material known as vulcanite or ebonite.

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  • There is some evidence that " tackiness " may be induced by a kind of fermentation which takes place in crude rubber.

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  • Rubber slowly absorbs oxygen when exposed to air and light, the absorption of oxygen being accompanied by a gradual change in the characteristic properties of rubber, and ultimately to the production of a hard, inelastic, brittle substance containing oxygen.

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  • Ozone at once attacks rubber, rapidly destroying it.

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  • If ozone is passed into a solution of rubber in chloroform the caoutchouc combines with a molecule of ozone forming a compound of the empirical composition C 5 H 8 O 8.

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  • Commercial Treatment of Rubber.

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  • In the industrial working of indiarubber, the various impurities present in the crude " wild rubber (bark, dirt and the principal impurities derived from the latex, except resin) are removed by the following process: The lumps of crude caoutchouc are first softened by the prolonged action of hot water, and then cut into slices by means of a sharp knife - generally by hand, as thus any large stones or other foreign substances can be removed.

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  • Solid impurities speedily become crushed, and are carried away by the water, while the rubber takes the form of an irregular sheet perforated by numerous holes.

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  • In the future this washing of " wild " rubber may be conducted in the tropics, thus furnishing the manufacturer with rubber which, like " plantation " rubber, need not be subjected to this process in the factory.

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  • The washed product contains in its pores a notable proportion of water, which is removed by hanging the rubber for some days in a warm room.

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  • Some of the rubber having been placed in the annular space between the inner cylinder and the outer casing, the former is made to revolve; and the continued kneading action to which the rubber is subjected works it into a solid mass, something like a gigantic sausage.

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  • To convert the masticated rubber into rectangular blocks, it is first softened by heat, and then forced into iron boxes or moulds.

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  • Most articles made of cut sheet rubber would, however, be of very limited utility were they not hardened or vulcanized by the action of sulphur or some compound of that element.

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  • If an article made of cut sheet be immersed for a few minutes in a bath of melted sulphur, maintained at a temperature of 120 0 C., the rubber absorbs about one-tenth of its weight of that element, and, although somewhat yellowish in colour from the presence of free sulphur, it is still unvulcanized, and unaltered as regards general properties.

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  • When a manufactured article has been saturated with sulphur in the melted sulphur bath, the heat necessary for vulcanization may be obtained either by highpressure steam, by heated glycerin, or by immersion in a sulphur bath heated to about 140° C. In this last case absorption of the sulphur and its intimate combination with the rubber occur simultaneously.

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