AROUND THE GLOBE, BETWEEN THE TROPICS OF CANCER AND CAPRICORN. known as Callotropis, Cynanchum and Periploca). that is to say, Pernambuco, Maranaham, and ing the equatorial belt, which is the true rubber belt. Here and there a little to the north, as in India and Mexico, and here and The Heveas grow principally in the great there a little to the south, as in Africa and Amazon Valley. The Castilloas grow in Australia, rubber is found, but not of the the South American upland, in Mexico, and best, and rarely in paying quantity. The some in Central America. The Manihots highest grades require tropical heat and much and the Hancornias grow in the mountainhumidity for the growth of the plant. It ous and sandy regions of South America,may be said here in passing that every one of these many plants, like the grape, yields a product the character of which is determined by the chemistry of the soil. The present great sources of the world's product of rubber are the Amazon Valley and the Congo. A future great source will undoubtedly be Ceylon and the Straits Settlements. The present crop, however, is entirely a natural and uncultivated one, whereas it is certain, as we shall see later, from the result of the experiments and work already done in Ceylon, that at no very distant time the future crop is bound to be a cultivated one. THE BOTANY OF RUBBER. I have spoken of the many plants which yield the gummy latex. Those which are really most worth mentioning, however, come from four great families,-the Euphorbiacea (which include the Heveas, Micranda, Manihots and Euphorbia), the UImacea (which include the Castilloa and Ficus), the Apocynaceae (which include the Landolphia, Urceoles, Hancornia, Alstonia, Kickxia, Carpodinus and Clitandra) and the Asclepiadea (which include the varieties LEAF, FRUIT AND CAPSULE OF THE LANDOLPHIA, Bahia for the Hancorrias, and Ceara for the Manihots. All of the plants already spoken of are trees. The characteristic of the African yield is generally that it comes from vines, and chief among these is the Landolphia. The principal source of rubber in Asia is the Ficus, or fig, with which we are all familiar in our conservatories and hot-houses as the "rubber plant," the leaf of which is supposed to be characteristic of all rubber plants, but is in no sense so, differing markedly from both the leaf of the Hevea tree and the Landolphia vine. vine, but this is scarcely the place. It may be said, however, that all rubber-yielding plants always grow best where the soil is moist and where there is a regular rainfall. It will readily be seen that the study of the habits of the plant is a necessary preliminary to the introduction of a new system of cultivated production. It has been made the subject of the closest possible study ever since the directors of the Botanical Gardens at Kew, in 1875, sent Mr. Cross to Central America to make a study of these plants and their habits, with a view to artificial cultivation in India. There, at the present time, many millions of trees have been planted, and a new industry is growing up, which bids fair to be one of the most profitable in the world. On this subject a little book has been written by Mr. Herbert The Carpodini and Clitandras are some of them small herbs, and some small shrubs, which are found in eastern and central Africa, and these are like the Guyualé of Mexico, which three latter constitute the basis of a great organization for the extraction of Wright, published at Colombo, in Ceylon, rubber which is controlled by a group of New York financiers, who have already undertaken the extraction in Mexico on a very large scale and have entered into private arrangements with the King of Belgium for doing the same in the Congo. It would be interesting for those who have the time and the inclination to study the habits of the Hevea tree and the Landolphia EMPTYING THE CUPS-SOUTH AMERICA. which is not to be had elsewhere, and which I would recommend to all to read in conjunction with Dr. Karl Otto Weber's "Chemistry of Rubber," and Franz Clouth's "Rubber, Gutta Percha, and Balata," which are the only three books that are really necessary to the student, but to which we may add Wildeman & Gentil's "Lianes Caoutchoutifères," or "Rubber Vines of the Congo," which was published in Brussels, about three years ago. THE CHEMISTRY OF RUBBER. But now we may stop and ask what precisely is rubber? We know that it is a white vegetable latex; that when drawn from the plant it looks like milk. In fact, it looks precisely like the milk of the milk-weed, which is allied to the rubber-yielding herbs. We know that when dried it loses its white color, becomes coagulated, and is then a more or less elastic and sticky solid. It belongs to the great class of solids known to chemistry as colloids, a good type of which is gelatine. But the chemists agree that we are in almost complete ignorance of the real nature of the colloidal state, and it is this fundamental ignorance which leaves the industrial chemistry of rubber in what is as yet a very primitive stage. It is a carbo-hydrate, and I might venture a fairly scientific definition of it as follows: A white or nearly colorless colloid, with a specific gravity of about 92 at a temperature of 17 degrees C., the product of a vegetable latex, and the quantitative composition of which may be expressed by the symbol C10H16. Weber quotes Seligman as having analyzed the latex of the Hevea as follows: Before rubber can be used at all, all the water has to be dried from the latex. It has now been discovered that the quantity of proteids, resin, and ash depends very largely upon the chemistry of the soil, and not only affects the elasticity and tensile strength of manufactured goods, but their durability, and that they constitute a very material element in the matter of "tractability" in preparing the raw material for use. The finest rubber from Para has, for instance, been found to contain less than 12 per cent. of resinous extract, while at the other extreme African flake contains over 60 per cent., and this is the chief determinant in their industrial and market values. The rubber itself, which is held in suspense in the latex, is really colorless, exists in globules in suspense in the water of the compound, and is lighter than the water. In the coagulation of the latex, which is a process of fermentation accompanied by drying, the resin becomes part and parcel of the rubber, and where it exists in large quantities the difficulty and tediousness of the task of extracting it is one of the chief elements in the marketability of the product. The proteid, or albuminous matter, which may amount to 4 per cent. of the dry rubber, is of a most complex nature, and that also affects the value of the rubber, for it is responsible for the development of bacteria in the finished product, which leads to its putrefaction, or to what is known to the trade as tackiness." What has been said is sufficient to indicate the tremendous amount of care and skill which is required in the purchase of the raw material from the long list of so-called rubbers, which differ vastly in their composition, to say nothing of the skill required in the practice of cleansing, compounding, and manufacture, lack of which may affect the product of a mill disastrously. HALF-SPIRAL SYSTEM OF TAPPING. become as closely identified with the industry as that of Goodyear, succeeded in 1823 in dissolving rubber in benzine, which was the beginning of the industry of waterproof clothing. In 1832 the house of Chaffee & Haskins, of New York, founded the Roxbury India Rubber Company, for the purpose of doing a business of the sort which MacIntosh was doing on the other side. They, however, did not succeed, but they had in their employ one Charles Goodyear, who devoted his life and his fortune to the discovery of what turned out to be the most practical of all methods of overcoming the adhesiveness or stickiness which militated against the commercial uses of the gum. Rubber was of far more interest to the Heywood was the first to discover that sulbotanist and to the chemist than to any one phur lessened the sticky quality of the raw else until toward the beginning of the nine- material, but it was left for Goodyear to teenth century. From 1791 to 1815 a num- demonstrate, in 1839, that by the combinaber of English chemists tried to avail of a tion of rubber and sulphur in proper quanrubber solution for the purpose of making tities and under proper temperature, the waterproof cloth, but quite unsuccessfully. product would not break at a low temperaCharles MacIntosh, whose name has now ture, and would not become sticky at a high THE PROCESS OF MANUFACTURE. one. This was the solution of the problem, unforeseeable, at the time when La Condaand it is this combination of rubber and sul- mine called the attention of the Academy of phur under the action of different tempera- Sciences in Paris to his interesting little balls tures, resulting in a product of different of gum. hardness and elasticity, which is known as "vulcanization." VOLUME OF RUBBER PRODUCTION. His discovery places Goodyear among the There has always been much difficulty in greatest of American inventors. Prior to making any accurate statistics of the world's his time practically no rubber was used in production of rubber, because not only of the United States. To-day we are using the diversity of the markets, but of the fact quite one-half of the world's product, and rubber may now be regarded as a prime necessary of life, and one of the things which enters as closely as anything else into the satisfactory solution of the tremendous problems of transportation and communication. Without it the air-brake would be an impossibility, and without it it would be impossible to insulate the wires which are used in all the departments of electrical conduction. To say this is enough to show how essential to industrial progress rubber has become. The world might get on without it for shoes and clothing, if the worst were to come to the worst, but for the purposes of transportation under progressive conditions on the railway train and on the automobile, for purposes of insulation for electrical communication and lighting, and for the purposes to which it is put by the medical and surgical professions, rubber is an absolute essential for which there is no substitute, and that is why it has come to play so large a part in the history of progress, a thing unforeseeable, as the whole modern progress itself was that the same rubber may appear in a number of different markets, and in one statement after another, thus improperly multiplying itself for statistical purposes. Without attempting here to go into the details, it may be said generally that the market value of the world's total production of crude rubber is about $80,000,000; that the market value of the crude rubber which passes through the port of Para alone is about $50,000,000; that the total volume of the world's production, expressed in terms of weight, is about 125,000,000 pounds, of which the volume of Para rubber is about 75,000,000 pounds. The value of the product of the Amazon Valley is about 65 per cent. of the total product expressed in terms of money, leaving about 35 per cent. for the rest of the world, and in terms of weight about 60 per cent., leaving some 40 per cent. for the rest of the world. The European and the American consumption of all grades is about equal. The balance was thrown out for a while after the tremendous development of the automo VIEW OF A RUBBER ESTATE AT KLANG-SELANGOR. FEDERATED MALAY STATES. there was received in Liverpool: from Para. Of South American grades other than those kri, Lahou and Mahou Twists). Tons. 1,249 1,734 834 1,000 bile industry in Europe, but the consumption or, taking the year 1905 as an illustration, is about equally divided now between Europe and the United States. This country, however, consumes a larger proportion of the Para grades. For instance, out of the crop of 1904, which was a crop of highest prices, the American consumption of Para grades was estimated to have been about $28,000,000, while the European consumption of the same grades was estimated to be about $23,000,000. During that year America consumed, both in volume and value, 54.4 per cent. of the Para crop, and Europe 45.6 per cent. The statistics for the Para crop may be treated as fairly reliable, but this cannot be said with regard to any of the other crops. THE RUBBER MARKETS OF THE WORLD. The world's great rubber markets for distribution to consumers are New York, Liverpool, London, Antwerp, Hamburg, Lisbon, and Havre. The Liverpool imports of all grades are about 40 per cent. of the Para crop; of other grades it handles between 6000 and 6500 tons of 2000 pounds each, Cake) 475 126 919 Many of these same grades get into the London market, but indirectly. While London is the direct market for Rangoon, Assam, Penang, Borneo, Mozambique, and Madagascar grades and some South American grades, which come out at points below Bahia, the total receipts of such grades in London by way of direct import are about 1500 tons a year. All of the rubber from the Congo Free State goes to Antwerp, the direct imports into the latter market having averaged about 5500 tons yearly for the last seven years. And this Congo or Antwerp crop of, say, 11,000,000 pounds, may be taken as of an |