November, 1926 YEARLYAPPLICATION crop improvement Year Per cent 1 15 2 27 3 96 4 79 5 146
INDUSTRIAL A-VD ENGINEERING CHEMISTRY MANURES APPLIEDEVERYT w o YEARS Crop improvement Year Per cent 1 (manure) 14 2 (no manure) 57 3 (manure) 56 4 (no manure) 102
The benefit to the estate owner derived from proper manuring practice can perhaps be shown by the results obtained on one property in 1924. The yield of annually manured plots was a t the rate of 514 pounds per acre, that from biennially manured plots 447 pounds per acre as against 235 pounds on unmanured control plots. The manuring of good soils has not so far yielded such striking results; in fact, very little increase has been shown. Whether or not benefit can be obtained remains to be determined by careful experiment. There are many other important researches going on in the Far East that may bear fruit and any one of the few topics
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mentioned above might be elaborated and discussed ad infinitum. It is only possible here to give a few of the more striking instances where the scientists have greatly contributed to the prosperity of the planter. The wealth of scientific material available is amazing and reminds me of an experience I had many years ago when I first went to the Far East. I was visiting a famous rubber estate in charge of a man who has since become one of the leading figures in the industry, but who a t that time had only been recently weaned away from sugar-planting to rubber-planting. After kindly showing me around the estate and trying to instil into my young mind as much of the art of rubberplanting as possible, be turned to me and said in a broad Scotch accent-"My lad, the rubber tree is fool-proof. Any d-n fool can plant rubber, but it takes brains to make sugar." My friend was no doubt right about sugar, but if he was also right about rubber, then many good men are deceiving themselves tragically.
Possibilities of Wild and Plantation Rubber Production in Tropical America and Africa By H. N. Whitford 250 WEST 57TX ST.. h'EW YORK. N. Y
HE uneasiness that exists in the consuming markets about the future sources of rubber brings to the front again the possibilities of increase in the production of wild rubber, especially that from the American and African tropics. I n so far as we can see now, and assuming there will be a normal increase in the consumption of rubber COILqervatively estimated a t an average of only 5 per cent per year during the next five years, the amount of natural rubber furnished the world will not meet the expected demand beginning about 1929 and continuing until there is a very large increase in acreage. While a discussion of the basis of this prediction is another story, yet it has a bearing on the subject of this paper, and therefore needs brief mention. The estimated production for the next five years is based on a fairly accurate known acreage of planted rubber, all of which will be in bearing by 1930, and nearly all of which will be ten years old and over and therefore in full production. The average per acre production has been raised to a figure that is considerably higher than the planted rubber has yielded in the past. Judging from the trend of production for 1926, the average yield per acre will be lower rather than higher than that predicted. To the total amount expected from the plantations of the Middle East there has been added an estimated production of rubber from tropical America and Africa of 40,000 tons per year. Aside from increased quantities coming from the rubber planted by native?, especially in the Dutch East Indies for which there is still great uncertainty, there is little chance of an increase in the estimated production of rubber from the present planted area of the Middle East. There remains, then, the only other sources of an increase in the natural rubber, above that which has been estimatedviz., that of tropical America and Africa. I t is believed that if it were economically practicable to reach and gather the latex from the millions of rubber-bearing trees, vines, and shrubs of tropical America and Africa, these regions could supply to the world sufficient rubber annually to more than meet the predicted shortage. The economic limitations are such, however, that the possibilities of their doing so are very remote.
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As a basis for judging the practicability of increasing t h e supply of the classes from tropical America and Africa, we must depend largely on the situation in the past. We now have fairly accurate statistics of the amount of shipments of rubber for the past quarter of a century. A study of these statistics shows some interesting comparisons. First, the relations that exist between the production of plantation and wild rubber are worthy of consideration. Production of Plantation and Wild Rubber During the twenty-five years beginning with 1901 and ending 1925, there have been placed on the market about 4,767,000 tons of rubber. I n this period 3,436,000 tons, or 72 per cent, came from the plantations of the Middle East, and 1,321,000 tons, or 28 per cent, from tropical America and Africa. During the first quinquennium (1901-1905) the amount of plantation rubber reaching the market was negligible, and the world's supply of rubber Tas furnished by wild rubber principally from tropical America and Africa, in all 287,000 tons, or 57,400 tons per year. In the next quinquennium (1906-1910) the total amount produced was 341,000, or 68,000 per year; plantation rubber of the Middle East amounted to 5 per cent, the remainder 95 per cent, coming from tropical America and Africa. In the third quinquennium (1911-1915) the total was 614,000, or an average 122,800 tons per year; plantation rubber amounted to 48 per cent and wild rubber 52 per cent. I n the fourth period (1916-1920) out of a total of 1,452,000 tons or an annual average of 290,400 tons, 83 per cent was plantation rubber from the Middle East and 17 per cent from tropical America and Africa. I n the fifth period (1921-1925) with a total of 2,063,000, or a yearly average of 412,600 tons, 93 per cent was from the plantations of South Eastern Asia, and 7 per cent from tropical America and Africa. Past Production of Wild Rubber and Price During the first period of five years (1901-1905) of the twentieth century, wild rubber met with little competition from the plantation product, for practically all the rubber
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t h a t was produced during this period was wild. The total was 287,000 tons, or at the average rate of 57,400 tons per year. During this period the average declared value per pound of rubber entering the United States was 63.7 cents. During the second quinquennium (1906-1910) wild rubber reached its peak in production and price. The total amount was 326,000, or a t the average rate of 65,200 tons per year. The declared value of that portion of it reaching the United States was 79.8 cents. The peak year of production during this period was in 1910, when the declared value in the United States was nearly $1.09 and spot rubber in London was as high as 12 shillings, 10 pence. During the third quinquennium (1911-1915) the tota poduction was 319,000 tons, or a n average annual of wild rubber of 63,800, the declared value of that part entering the United States being 63.5 cents. I n the fourth period (1916-1920) the total had fallen to 240,000 tons, the average dropping to 48,000 tons per year. The average declared value was 46.9 cents. I n the fifth period (1921-1925) the total production of wild rubber was 149,000 tons with a n average annual of 29,800 tons. The United States import price during this period was 28.3 cents per pound. I n each of the first four of these five years the declared value price was below 30 cents, with a n average production considerably below 30,000; in 1925, with a declared vaIue of 48.36, the production jumped to nearly 40,000. Assuming that the general economic conditions are approximately the same now as in the past, and the tappable supply of rubber is not much different than then, we can expect production of wild rubber depending on price somewhat as follows: Price Cents Below 30 30 t o 40 40 t o 50 50 t o 60 Over 60
Production Tons 20,000 to 30,000 30,000 t o 40,000 40,000 to 50,000 50,000 t o 60,000 60,000 t o 70,000
Even with prices of 70 cents or over production seems not to have been increased much beyond 70,000 tons, indicating that at such times the economic capacity of the regions to produce rubber had been reached. Amazon Region The Amazon region is the principal source of rubber in tropical America and Africa. It has produced from 60 to 80 per cent annually of all the rubber furnished by the two continents during the past twenty-five years. The only estimate of the number of trees of Para rubber existing in the Amazon is 300 million. This figure seems ridiculously high when it is calculated that with a low average of 4.5 pounds of rubber per tree per year, if all the trees could be reached and tapped regularly, there would be a production of about 600,000 tons of rubber annually. The disbelief in this high number of trees existing in the Amazon is further reenforced when it is remembered that in its peak year of production the Amazon furnished only 45,000 tons of rubber, 18 per cent of which was the product of Castilla trees, leaving 37,000 tons credited to Hevea rubber. At a n average of 4.5 pounds of rubber per tree, this would mean that only 18,400,000 trees were tapped, or about 6 per cent of the estimated number of trees reported to be existing! If the claim that Brazilian trees produce a yearly average of 8 pounds per tree be substantiated, then only 10 million or 3l/3 per cent of the estimated total were tapped during the peak year of production. While there is little doubt that there are large reserves of rubber that have never been tapped, especially .on the northern slopes of the Matto Grosso plateau, yet it is difficult to believe that, all told, there can be anything like sixteen times as many as had been tapped in the peak year of production.
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Concerning the price that will stimulate production in the Amazon, a report of the Department of Commerce states as follows:’ Taking all these factors into consideration i t would appear that a sufficiently high price, extended over a few years, might bring the exportation up to that of 1912. I n t h a t year the price in Para ranged from 4$220 to 5$280 per kilo, corresponding t o $0.62 to $0.78 a pound at par. Since the tendency t o increase production is shown when the price rises t o 4t000 per kilo in Manaos or Para, it is difficult t o say what price would be necessary t o bring production back t o this highest point, bearing in mind the somewhat different conditions t h a t prevail todayas, for example, the higher cost of imported supplies. Under present conditions of working and financing, our opinion is that it would have to be around S$OOO per kilo in Para and Manaos, corresponding at the average rate of exchange for 1923 t o $0.37 U. S. a pound.
Since the foregoing was written, the mihlreis has increased in value so that 8WOO per kilo for rubber in Para and Manaos would correspond to about $0.56 U. S. a pound. It will be seen that with a London price of 21 pence (42 cents) that fixed by the British restriction officials for rubber would fall far short of being enough to attain a return to maximum production n the Amazon valley, provided the 8$000 per kilo is the lowest figure that is required to bring back production in the Amazon to the highest point. It is significant, however, that even with very low prices for rubber that prevailed during, the period from 1920 to 1924, production of rubber from the Amazon was maintained a t about one-half the amount produced in the peak year of shipments, or about a n average of 22,000 tons. Recent figures indicate that the present production of the Amazon is being rr-aintained at about 25,000 tons. It is generally believed that with 42-cent rubber in New York the Amazon supplies can be figured a t around this amount per year, and a t prices considerably higher than this more will be forthcoming. Aside from price of rubber, the limiting factors are a lack of capital and laborers. With higher priced rubber more labor would be attracted from the semi-arid regions of northeastern Brazil. With lower prices local labor seeks employment in other extractive industries, such as lumbering, cotlection of Brazil and palm nuts, and to some extent agricultural pursuits. The last is especially true in Peru. The higher the prices obtained for such products, the greater the pull away from rubber. While all factors point to a production of around 25,000 tons per year of rubber for the Amazon when the rubber is around 42 cents in New York, a slump in prices for the other extractive products for which labor is required may possibly bring the shipments up to a maximum of 30,000 tons per year. Castilla Rubber Castilla rubber, usually known on the market as caucho and centrals, furnished the next largest supplies of American rubber to the market. Castilla rubber is indigenous to all northern tropical American countries from southern Mexico to the Amazon and western Ecuador, except Venezuela, the Guianas and the West Indies. I n the past, plantations were started in practically all of the countries of northern tropical America except the Amazon. These plantations, while of considerable but unknown acreage, seem to have furnished a n insignificant amount of rubber of this class to markets, because it has been more expensive to tap them, owing mainly to the fact that the yield from planted trees is less than wild trees. Moreover, it is probable that in spite of laws prohibiting destruction of the trees in many of the countries, the greatest amounts come from trees that are cut down before the rubber is extracted. As already stated, about 18 per cent, in some years more or less, of the ship1
“Rubber Production in t h e Amazon Valley,” p. 39.
November, 1926
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ments of rubber from the Amazon is Castilla known on the understood that the abandoned areas have suffered severely market as caucho balls. While the market price of all Cas- from fires. It is reported that recently tapping has been tilla rubber is much below that of Hevea, that of the Amazon, resumed on what is left of these plantings. Wild rubber is obtained mainly from Funtumia elastica, the product of Castilla ulei, commands the highest price of this class of rubber. That of western Ecuador, coming from a tree that is found in the equatoria West and Central one or more unknown species of Castilla, stands next to that of Africa, and Landolphia and related genera, the so-called vine the Amazon caucho. The centrals and corinto scrap from and “root” rubber of Africa. These vines and shrubs have other species of this genus of Central America and Mexico a much wider distribution than Funtumia. While there are ie the poorest quality judging from the price. Caucho rub- rubber-producing species in Africa other than those mentioned ber from the Amazon costs less to collect than Hevea; hence above, in the aggregate they seem to have yielded a very although the price is lower its collection varies in accordance small proportion of the total production. Like Castilla, the cost of gathering the latex from wild rubber plants in with New York price of Hevea. I n western Ecuador a New York price of 25 cents or more Africa by tapping without destroying them is greater than by on this class of rubber is considered a stimulative one for the gathering the latex after the plants are cut down. I n the collection of wild rubber. I n Central America there are no early days the latter method was the rule. Existing laws reliable figures on costs of collection of wild rubber, but it is prohibiting such destruction can probably be enforced to a limited extent. Past destruction of rubber plants is said to probably higher than in western Ecuador. A much higher price for centrals than at present exists have depleted large areas, especially those most accessible. seems necessary to warrant the opening up of the old plantings Contrasted with this, a sufficient time has elapsed since the of Castilla in Mexico. It is believed that a 40-cent Yew wholesale destruction to allow younger plants to reach tapping York price for centrals would stimulate its collection some- age. Lately, however, considerable areas of rubber-producing what, although probably it would take n price between 50 forests have been destroyed to make way for the planting o r 60 cents for centrals to bring out full production from this of other crops of various kinds. Many regions, on the other one region. Full production from planted Castilla alone hand have better transportation facilities than formerly and is roughly estimated at 3000 to 4000 pounds. While un- this might encourage opening up new areas. Here, as in the Amazon and other parts of tropical America, reliable figures of exports of Castilla rubber from Mexico indicate that in 1910 and 1911 between 7000 and 8000 tons the population that could be diverted to rubber-collecting were shipped, i t is believed that such amounts, if obtained, depends more or less on the profit that can be made on other were taken mostly from wild and not planted trees. To wild extractive products, such as lumber,. palm nuts, etc., sum up, with the price of Hevea rubber around 42 cents in and the price obtained for planted crops like cacao, cotton, New York, we can expect 5000 tons per year a t the most and coffee. With low prices for such products we could expect from the Amazon and perhaps 4000 tons of Castilla rubber larger supplies of rubber; with high prices less quantities will be forthcoming. Taking everything into consideration, it from all other sources in America. Peems reasonable to suppose that with a New York price of Africa around 42 cents the production of rubber from Africa might During the last quarter of a century rubber production in possibly reach a level of 10,000 tons annually. Africa reached a total of over 20,000 tons in two years, once Summary i n 1906 and again in 1910. Probably due to war disturbances the shipments of rubber from this continent fell off rapidly in 1-In the past the amount of rubber annually shipped from 1914 and 1915. I n 1916 and 1917, with the declared value tropical America and Africa has been mainly controlled by the around 50 cents, a level of about 10,000 tons was reached. price obtained for the product. I n 1918, with a declared value of United States imports reach%-With the United States declared import price below 30 ing a level of about 45 cents, the production fell to 7000 tons. cents, the amount has usually been under 30,000 tons. I n 1919, with a price of 40 cents, 7000 tons were shipped, and 3-T17ith a higher price there has been a gradually increasing 6500 tons were shipped in 1920 when the price was near 43 cents. I n 1921, 1922, and 1923 the amounts received in the amount reaching the markets. In general, the statistics principal consuming countries were between 3000 and 4000 show that for any five-year period the amounts shipped betons, with the respective declared United States value prices tween 60,000 and 70,000 tons with an average declared about 17.76, 18.10, and 26.72 cents. However, in 1924, United States price of 60 or more cents per pound. 4-In one five-year period (1906-1910) the average price with a price of 23.71 cents, nearly 5700 tons were shipped and in 1925, with an average United States import price of 48.36 was nearly 80 cents per pound with an average of 65,000 tons per year. cents, the shipments reached over 7000 tons. 5-In four years of very highest prices the production An element to be considered in the future production in Africa in contrast with tropical America is planted rubber. averaged around 70,000 tons;. These years were 1909-1912, While there are only a few hundred acres of planted Hevea with the United States declared value of 84.35, 108.73, rubber commercially developed in tropical America (all in 89.81, and 84.34 cents, respectively. While it is believed that, Trinidad), the acreage of this species in tropical Africa is potentially, the regions might produce much more rubber estimated to be around 38,000. If regularly and fully tapped with such prices prevailing, yet it is quite possible the prothis might produce 5000 tons of Hevea rubber annually. Un- duction in the wild rubber forests had reached their maximum fortunately such statistics as are available do not completely limits with the labor available a t that time. separate wild from planted rubber, so that the proportion 6-During the years 1926, 1927, and 1928, with the exbetween wild and planted rubber cannot be determined. Be- pected production exceeding the predicted consumption, sides Hevea there is comparatively large but unknown acreage and with British restrictions in effect, we can expect an of Funtumia, Ceara, and Castilla rubber planted in Africa. average price of rubber near 42 cents and a production of I n former German East Ifrica, now Tanganyika, over 100,000 rubber from tropical America and Africa of about 40,000 acres of Ceara rubber had been planted previous to 1914. tons, 30,000 tons from tropical America, and 10,000 tons I n 1912 and 1913 these plantations shipped 1030 and 1287 from Africa. tons of rubber, respectively. I n 1914, 812 tons were shipped. 7-From 1929 on, and until enough rubber is planted and Owing to war conditions tapping ceased after this, and it is has come into bearing to meet the deficit, and if the normal
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increase in consumption is maintained, we can expect the situation to some extent but would not wholly solve the world’s capacity to produce enough natural rubber to meet estimated shortage problem. the consumption to be greatly strained, and then much higher IC-Ninety-eight per cent of the natural rubber used today prices might rule. Such prices ought to stimulate greater comes from one species, Hevea brasiliensis, 94 per cent of production from tropical America and Africa of wild rubber which is furnished by planted crops and 4 per cent by wild and, if high enough, the shipments might again reach 70,000 trees in the forests of the Amazon Valley. Past experience tons annually. Even more might be forthcoming if the col- shows that, while other natural rubbers and reclaimed rubber lecting industry of the Amazon especially could be better can be used for special purposes and give as good service organized and enough capital made available to open up the as, and in some few cases better than, Hevea rubber, yet, more remote sources of supply. in so far as can be foreseen, the extent to which such rubbers 8-Such a n increase, together with the problematic in- can be substituted without deterioration in the quality of the crease in production of rubber from the native planta- manufactured goods is distinctly limited. The manufacturer tions of the Dutch East Indies, might be sufficient a t least of rubber goods exceeds these limits to meet the demand for to postpone the day of very acute shortage of natural a low-priced article or when he is compelled to do so by famine rubber. prices for Hevea. 9-Famine prices for natural rubber, if they come, will 11-While future developments may show that there are again reduce its consumption below normal, will stimulate other natural rubbers as good as Hevea, yet today Hevea research of the chemist to produce a better quality of re- rubber is not only recognized as the best rubber, but as a claimed rubber, and there is always the remote possibility planted product it can be raised at a cost cheaper than any of synthetic rubber. Such problems are up to the chemists. other natural rubber. Large quantities of wild Hevea can The possibilities in these two directions are so remote, how- be placed on the market only when the price of rubber is ever, that it would be folly to place too much reliance on high, much higher than the cost of raising it on plantations. absolute success-that is, a reclaimed rubber as good as The only absolute assurance that the consumer can have of a natural Hevea rubber, and synthetic rubber equal in quality sufficient supply of Hevea rubber to meet a normal increase and as cheap as that produced by Nature’s chemical labora- in consumption is to see to it that there is a sufficiently large tory. Partial success in these directions would relieve the planted acreage to furnish the quantities needed.
Recent Developments in the Preparation of Plantation Rubber By Henry P. Stevens 15 BOROUGH HIGHST., LONDON, S. E. 1,
H E R E are no radical alterations to be looked for in the preparation of plantation rubber in the future. As a whole, present methods are satisfactory; the product good and the general principles correct. The most to be expected is a n improvement in the details and preparation of sheet and crepe rubber of greater uniformity, as well as freedom from mold, spots, and other minor defects.
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Coagulation
The most essential process for the conversion of liquid latex into solid rubber is the coagulation. The time is now past when the use of acid or other chemicals for this purpose can be condemned or even questioned. Nor can we go back to the laborious native process of smoking as practiced from the earliest times in the valleys of the Amazon. Such would be a retrograde step. As for the relative qualities of plantation and fine Para, it would be strange indeed if a crude native curing process yielded a superior or more uniform product than that produced by an up-to-date estate run on the most approved lines. The main deficiency in uniformity results from the large number of estates, some of which are not so u p to date as others, and the mingling of native-prepared with plantation-prepared so that the rubber manufacturer has no means of knowing or selecting suitable material except by a n actual test of the product offered to him. I n regard to acidity, it does not seem to be realized that the amount of acid used in coagulating latex is extremely small and that the acid is a, volatile organic acid. One part of acetic acid coagulates 1200 parts of latex standardized to 2 pounds dry rubber to the gallon. The presence of acid cannot be detected by the ordinary reagents in first-grade (standard) crepe rubber and sometimes not in sheet rubber, but it can always be detected in fine Para. From this evidence it
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might be concluded that acid is not harmful and may even be beneficial. As a fact, acid is harmful if used in large excess, particularly if a strong nonvolatile acid such as sulfuric acid is employed. I n the early days of plantation research various acids and acid salts were tried, but nothing more suitable than acetic acid was discovered and many were quite unsuitable, such as hydrochloric and phosphoric acids. The use of alum was banned by edict in the Federated Malay States. Alum is not so bad a coagulant as has been suggested. It does not damage the rubber, but results in a slower curing product. It is certainly not so harmful in this respect a s sulfuric acid, which was used to a large extent during the war when acetic acid was not procurable. Alum is also a n easier substance for a native to handle than a corrosive liquid such as acetic acid. The Dutch have not put any restriction on the use of alum; indeed, de Vries regards it as a very suitable coagulant for the native producer; its tendency to reduce t h e rate of cure being counterbalanced by the usual native procedure of allowing the rubber to mature. Recently the Rubber Association of America addressed a letter to the Rubber Growers’ Association of Great Britain dealing with the use of sulfuric acid as a coagulant and expressing apprehension of the probable harmful effect which would be produced on t h e curing and aging qualities of the rubber. The Rubber Growers’ Association has always discouraged the use of sulfuric acid as a latex coagulant and very little, if any, is used for this purpose at the present day.’ The writer’s objection to sulfuric acid is its influence on the rate of vulcanization of the resultant rubber. If the sulfuric acid is kept at a minimum, say, 1 part per 2000 of latex, the effect k not very marked-for instance, the time required to vulcanize a simple rubber-sulfur 9:1 mix is increased by about 10 or 12 per cent, 1
Bull. Rubber Growers’ Assoc., May, 1923.
