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Bouncing Back: Bringing Rubber to Grantville

Written by Iver P. Cooper

Chemistry Professor Joe Schwarcz writes, "It's hard to fight an effective war without rubber. Fan belts, gaskets, gas masks, and tires are critical to the war effort." While he had modern warfare in mind, Grantville's war machines—modified cars and trucks—need rubber to remain functional. In 1633, Quentin Underwood insisted that "developing a rubber industry should be a top priority."

Rubber has myriad useful properties. Its most unique feature is elasticity, which allows it to be used as a shock absorber. Because of its toughness, articles made of rubber have good abrasion resistance. Rubber is also impermeable to gases and liquids. Finally, it is an electrical insulator. Rubber is used in hundreds of automobile parts; the apt slogan of the B.F. Goodrich Company was, "Everything in Rubber."

In the old timeline, synthetic rubber accounted for about 60% of all rubber consumed. Synthetic rubber is not an option within, say, a decade or two of the Ring of Fire. Even though we know, from the encyclopedias, that the secret is to co-polymerize butadiene and styrene (or acrylonitrile), where exactly are the butadiene and styrene coming from? Well, we can make butadiene from alcohol, or from petroleum ingredients like butane or butylene. To make styrene, we need ethyl benzene.

Schwarcz comments that the process which the Germans used to make Buna-S rubber (the butadiene-styrene copolymer) "was not a simple business." You need the right catalyst, the right emulsifier, and so on. This detailed process information probably isn't in the Grantville library system.

Even if we knew exactly what to do, to handle the chemicals, we need steel and glass, both of which are going to be expensive to make. And for the raw materials, we have to appropriately process coal or petroleum. All in all, the obstacles are numerous and formidable. Once they are surmounted, the synthetic rubber industry will still have to compete with other industries for key materials (coal tar, petroleum, etc.) and skilled workers.

Prospective Natural Rubber Sources

Our immediate source of rubber will be scrap (see "Rubber Reclaiming," below). However, even with reclaiming, we will eventually run out of rubber. So we need to find natural rubber, and quickly.

Natural rubber is found in latex, a sticky liquid exuded from wounds by certain plants. It is not sap, although non-botanists may confuse the two. There are several encyclopedias available in Grantville, and from them, one can compile a seemingly impressive list (see Appendix 1) of possible rubber sources. However, we need to know where to look and what kind of plant to look for. The best prospects fall into three categories:

(1) New World Tropical Rubber Plants: the Para Rubber Tree/Hevea brasiliensis (Amazon and Guianas), the Ceara Rubber Tree/Manihot glaziovii (northeast Brazil), and the Castilla Rubber Tree/Castilla elastica (Mexico to Peru).

(2) Old World Tropical Rubber Plants: the Lagos Rubber Tree/Funtumia elastica (West Africa), the Assam Rubber Tree/Ficus elastica (Asia), and various rubber vines (Africa and Asia).

(3) Temperate Latex-Producing Plants included in the Ring of Fire or commonplace in Europe: milkweed and goldenrod in particular.

For each of those rubber sources, we have both a written description, and some kind of useful illustration (its overall form, its leaves, its flowers (if any), its seeds, and so forth).

There are also some borderline prospects: the Pernambuco Rubber Tree/Hancornia speciosa, Guayule/Parthenium argentatum and Russian dandelion/Taraxacum kok-saghyz, which are of interest mainly because they can be grown outside a tropical rainforest. In the case of Hancornia and Guayule, the encyclopedias offer only a written description, but there are illustrations and a range map for Guayule in a 1981 National Geographic article. For Russian dandelion, there is just the prayer (which will be answered) that it resembles the common dandelion.

Knowing Where to Search

The 1911 Encyclopedia Britannica and the Encyclopedia Americana name where wild rubber occurs, by country (e.g., Mexico) or even just by region (e.g., Africa). Obviously, it is more useful to know that it occurs in a small country like Liberia than in a large country like Brazil.

Collier's Encyclopedia and the World Book Encyclopedia have maps showing more specifically where wild rubber and plantation rubber are found. There is also useful information in the economic maps of the Hammond Citation Atlas. However, these maps must be used with caution.

First of all, they show the current range of the rubber trees. The wild rubber may be available, in 1632, from a wider area, and the plantation rubber may be cultivatable in locations other than those shown on the map.

Secondly, they don't distinguish one kind of wild rubber from another, and the ranges do overlap. A given site in the marked region in Africa could be native to the tree Funtumia elastica, or to one or more of the many rubber vines which Africa possesses. Likewise, Castilla elastica and Hevea guianensis are both found in northern South America. So what this means is that 1632 characters should keep an open mind when they look for latex-producing plants.

In any event, knowing where to search is not enough. You have to be able to carry out the search successfully. This has two components: being able to identify the rubber plant (see next section), and being able to survive the journey (see "The Geopolitics of Foreign Rubber," below). The latter section also provides more detailed information on where the plants can be found or cultivated.

Identifying the Rubber Plant

Once we are in the right area, we can hire native guides, show them pictures (and latex or rubber samples), and ask them to guide us to where the trees are located. Or we can stumble around the rainforests ourselves, if we are nervous about the native attitude to European visitors.

Appendix 1 lists the descriptive information that is available for each of the known rubber sources. I am not going to quote the actual text, since it is readily available in libraries or on the internet.

However, I think it fair to warn you that the plant life of the rainforest is very diverse, and it is possible to be deceived by a closely related species that is a poor producer. For example, in Brazil, the leading rubber tree, Hevea brasiliensis, may be confused with Hevea spruceana (just to complicate matters further, there are interspecies crosses in the coastal regions), and in West Africa, those seeking Funtumia elastica may be misled into tapping Funtumia africana (the False Rubber Tree).(Polhamus, 36, 65; Christy, 78-9)

The Aztecs of Mexico and the Maya of the Yucatan and Central America used Castilla rubber for footgear, headgear, game balls, and incense (Shidrowitz, 2-5, 372-3). Because the rubber of this tree was used and even traded by the indios of Latin America, we don't actually need to be able to describe the tree in order to locate it. Chances are that if our agents go to the local markets in the correct general area, the Indians will know something about it.

Another special case is presented by the Indian Rubber Tree, Ficus elastica. This is one plant we don't have to journey far to find; it is a popular house plant, and I would be astounded if there were no specimens in Grantville.

The story of how Francois Fresnau found the Hevea brasiliensis tree in French Guiana is an interesting one, because the techniques he used could be adapted to finding any rubber tree whose latex production is already known to the natives. Fresnau was quite fortunate to succeed—albeit after a fourteen year search—because H. brasiliensis is rare in Guiana. (There is another rubber tree that is more common there, called Hevea guianensis, which was identified in 1764). Although he was a military engineer, assigned to the fort of Cayenne, he had been asked to keep his eyes open for exotic plants that might be of interest to the Royal Gardens. Fresnau was especially anxious to find Guianese specimens of the elastic resin-producing Syringe Tree of Portuguese Brazil. However, the natives he bribed with "gewgaws" and gin all told him, "Nimati" ("I don't know").

Then, by chance, Fresnau returned from a fishing trip on a boat crewed by Naurague Indians from Mayacare in Brazil. He showed them rubber articles, and they immediately realized which tree Fresnau was seeking. Because of his commitments, Fresnau could not travel to Mayacare, but he was resourceful enough to persuade them to make him clay models of the fruit and leaves of the Syringe Tree. He paid the Naurague for their troubles with liquor, salt and other presents.

Fresnau showed the clay models to native hunters and French colonial officials in various parts of Guiana and was told that the trees he sought were to be found on the banks of the Matarani River. He brought his Naurague Indians to the site, and they confirmed that the trees were of the correct species. (Schidrowitz, 14-22)

Rubber Collection Technology

There are two basic techniques of gathering rubber. First of all, we can make a small wound in the bark of the tree, and collect the latex that flows out, without killing off the tree. This is called tapping.

Secondly, we can cut down the rubber tree, or chop up the rubber shrub, vine or weed, and extract all of its rubber content. This may result in a large, quick return, but it is obviously wasteful (especially if the rubber source is a tree with a long maturation period).

Appendix 2 lists the standard collection technologies for each of the rubber sources that were singled out previously as hot prospects, as well as for a few borderline cases. It also gives the expected productivity on a per tree and per acre basis. If land is cheap, and labor expensive, then it may be more important to determine the productivity per tapper.

Rubber Tapping

At least 95% of all of the rubber produced today comes from the latex tubes of the Para Rubber Tree, Hevea brasiliensis. There is good reason for this. Latex can be repeatedly extracted from Hevea without killing the tree, the latex has a high rubber content, and the rubber itself is of excellent quality. A single tap produces only 56 grams of latex, but the tree can endure 150 tappings in a single year (EA).

The original method of gathering Hevea latex was both inefficient and destructive. The tree was nicked repeatedly, and latex bled from the injured areas (Dean, 10). EA says that the tapping that "inevitably resulted had led to the death" of the tapped tree.

Thanks to the work of Henry Ridley in Malaya in 1890-1910, it was recognized that it was better, from the point of view of long-term productivity, to make a single cut, position a cup underneath, and return later to collect the latex. It was also desirable to allow the tree to "rest" periodically. Finally, the cuts must be made with care to avoid the cambium layer. If the latter is penetrated, the trees will toughen their trunks, which will make further tapping more onerous.

If we want our collectors to follow these improved practices—which are described and illustrated in several of the encyclopedias—we will have to go with them to the trees and show them the proper technique. Moreover, if we want to make sure that they adhere to our instructions, we will have to make inspections from time to time.

In 1911, when the Encyclopedia Britannica, 11th ed. (EB11) was published, several different Para Rubber tapping methods were in use, and it was not yet known which would prove to be the best. The oldest was the V-system, in which V's were cut on the base of the tree, and a collection cup placed at the vertex of each. The width of each V was not more than one-quarter of the circumference of the tree. The V-system can be seen on two of the trees in the photo of Fig. 12.

The V-system had already been largely replaced by the herringbone system, which is depicted in Fig. 2. In essence, there is a central collection channel which leads down to a single collection cup. This main channel is fed by alternating tributaries, diagonals cut at a 45 degree angle.

The third method mentioned in the EB11 is the spiral system, which was then considered to be experimental. It involves making a series of spiral cuts, but the text does not elaborate on where the cuts start and end, how wide they are, how far apart they are spaced, and so forth. We can only judge this from the end result, which can be seen on three of the trees in the photo of Fig. 12. This shows spiral bands of cut bark, separated from each other by an unmarred region which is perhaps one-half to one-third the width of the cut bands. If I understand the system correctly, the cuts will ultimately be extended into this region, too, until the entire lower trunk has been sliced.

The cuts were, whichever the system used, made by means of "small knives and prickers," rather than machetes. In other words, by 1911 it was already recognized that the cuts should be no deeper than the latex-bearing layer.

The modern Hevea tapping method is a derivative of the spiral system; there is a diagram in the World Book Encyclopedia (WBE). The tapping of a virgin trunk begins with a single diagonal cut, starting four feet above the ground. It is angled downward, at what looks like a 30 degree angle (this is confirmed by the modern EB), and reaches halfway around the trunk. For the next tap, a parallel groove is cut just below the one before it. As this process continues, a "tapping panel," a diagonal band of scored bark, is created. (The cup is hung at the base of the fresh cut.) After three or four years, the tapping panel reaches the ground, and a new panel is started on the other side of the trunk. By the time this panel is completed, the originally tapped side has healed. For photos of tapping panels, see the modern EB and Collier's Encyclopedia (CE).

According to CE, the tapping should begin early in the morning. The WBE mentions that some plantations tap a tree every other day ("1T1R"), while others tap it for 15 consecutive days and then let the tree rest for 15 consecutive days ("15T15R"). CE says that the 15T15R method produces provides much greater amounts of latex than the other.

The Encyclopedia Americana (EA) entry provides more information about the cut itself. It is one twenty-fifth of an inch wide, and only one-quarter to one-half inch deep. However, EA suggests a cut that is only one-third, not one-half, the circumference of the trunk; hence, this approach contemplates carving three successive tapping panels into the trunk. In addition, the tapping panels contemplated by EA are only six inches high. (One tapping panel is thus the result of 150 tapping cuts, which presumably occurred over 300 calendar days.)

The only encyclopedia to provide any information concerning the standard methods of tapping the other rubber trees is EB11, and it must be remembered that the methods it advocates may not be optimal. For collecting the Castilla elastica latex, the EB11 recommends a simple spiral cut at a 45 degree angle. The Funtumia elastica latex was collected using the "herringbone" system. Pernambuco or Mangabeira Rubber (Hancornia speciosa) was obtained by making eight shallow, oblique cuts around the trunk, then allowing the latex to drip into cups.

The problem with the Ceara rubber tree (Manihot glaziovii) is that the latex flows very slowly. Hence, the latex allowed to coagulate on the tree, and the coagulate is then pulled off in strings. Some of the latex will drip down, and large leaves are laid down in advance to collect it. (EB11)

Tapping methods will affect labor efficiency. For Hevea, just one cut is made per tree per day; a plantation worker can tap 250-400 trees in a day. In contrast, a Castilla must be hacked repeatedly, because the latex-bearing cells are not connected; as a result, the same worker could tap only 20 or 50 Castilla trees daily. (Polhamus 264; Treadwell, 32)

Rubber Harvesting

In some cases, the latex cannot be tapped; the plant must be harvested and the latex recovered from the dead plant material.

If the plant can produce a rubber crop every year, then the main objection to this procedure is the labor cost involved in harvesting. The harvesting of milkweed and goldenrod are discussed below, in their own sections, while guayule and Russian dandelion are relegated to Appendices.

Latex is produced by several different African (and Asian) species of vines. To extract the rubber, the vine must be cut down, and unfortunately, when the price of rubber was high, this encouraged over-exploitation. The EB11 notes that the southern Sudan was "nearly entirely denuded." In consequence, the authorities in the French Sudan, the Congo, and in German Africa adopted regulations which limited when and how the vines could be tapped, and also required replanting. As the EB11 notes, these edicts can only be enforced "at considerable expense."

Library research in Grantville will reveal some information on how to extract the guayule rubber. EA says that 3- to 5- year old shrubs are shredded. The recommended collecting technique is to mow off just the top, so that the same plant can be harvested repeatedly. The latex is leached out of the plant material with hot water.

CE, on the other hand, says that the rubber is found in all parts except the leaves. It suggests that the collected plant material be "cured" (that is, left outside to ferment), chopped up, and macerated in water, after which the rubber is skimmed off the surface.

Latex Processing

The latex of the Para Rubber Tree is said to be about 41% rubber and 55% water (EB11); CE says 27%/70% and 36%/60%, respectively, for four and ten year old trees.

Hevea latex can be stabilized by the addition of ammonia or sodium sulfite (CE), and then concentrated (much like separating cream from milk) for shipping. Rubber gloves and toy balloons are made by dipping molds into latex and then allowing the acquired layer to dry. This is usually done several times, to increase the thickness of the rubber, and then the dipped article is removed from the mold. However, most latex is coagulated into rubber at or near the collection site, and only later shaped into a final product.

The Hevea latex is unstable; the rubber will gradually separate from the water, a process called "coagulation." This can be expedited by addition of an acid, since Hevea latex is alkaline. Crude Hevea plantation rubber was typically 94.6% rubber, 2.66% resin, 1.75% protein, 0.14% ash, and 0.85% water.

Grantville's only source of information concerning the handling of latex from other rubber trees is the EB11.

Castilla latex has the advantage that the rubber can be separated from the water by centrifugation. However, the standard processing method is to strain the "milk" through a wire sieve, add an alkaline plant juice (the Castilla latex is acidic) to cause coagulation, flatten out the coagulum to remove water bubbles, and then let the material dry for a few weeks.

In Africa, there was the curious practice of letting the Funtumia latex sit for half a month, covered with palm leaves, in a hollowed-out tree trunk. The trunk absorbs the water component, leaving the rubber behind. Another approach is to dilute the latex with water, and then heat it to coagulate the rubber. The Africans also employ plant-derived coagulating agents, but the bare reference to "Bauhinia leaves" is not likely to be of much use to us.

Perhaps the most important characteristic of Funtumia latex is not mentioned by the Grantville sources; it is very stable (Polhamus, 264). The same is true, to a lesser degree, of Castilla latex (102) and Ficus latex (264).

A number of natural latexes have a high resin content, and, if the resin is not removed, the rubber will be considered inferior. In 1911, solvent extraction of the resin was considered commercially impracticable, but that of course is very dependent on the price of the solvent as well as on the price difference between high resin and low resin rubber. EB11 shows that Ceara, Castilla and Ficus rubbers have average resin contents of 10.04%, 12.42%, and 11.8%, respectively.

Guayule rubber has a substantially higher resin content. According to CE, it is 20-25% for rubber extracted from the wild shrub, and about 16% in the case of the cultivated varieties. EA gives the resin content as 13-18%. It acknowledges that solvents have been used commercially to extract the resin, but does not provide particulars. The EB11 entry for "resin" says that it is "mostly soluble in alcohol, essential oils, ether and hot fatty oils." Curiously, CE states that the resin content is actually advantageous "as an aid to processing" when guayule rubber is blended with Hevea rubber.

Rubber Processing

A general problem with natural rubbers is the presence, inadvertent or deliberate, of gross impurities (dirt, chips of wood, leaf material, etc.) Such defects can be mitigated by filtering the latex (see above) and by washing the rubber.

The rubber initially conforms to the shape of the collecting cup and is called a biscuit. The spongy mass of rubber is washed (with hot or cold water) as it is passed between grooved rollers (EB11, Fig. 8), producing ribbed sheet. CE suggests use of a series of rollers, with progressively finer corrugations. It was then hung to dry. If a smokehouse is used, the product is called smoked sheet. Or it can be dried without resort to smoking, producing crepe rubber. The rubber can be softened with heat and compressed into blocks.

Additional shaping may be carried out in factories. After softening (if necessary), the rubber may be calendered (rolled), molded or extruded. By suitable incorporation of air, sponge and foam rubber can be formed. (WBE)

The rubber is warmed or masticated to soften it. The masticating machine (EB11, fig. 8) kneads the rubber, and, as this is happening, any desired additional ingredients (e.g., sulfur, carbon black, fillers, anti-aging compounds, colors, and oils), are mixed in. The rubber can then be softened further by heat and pressed into molds. One type of masticator, the rubber mill, has two rollers rotating inward, but at slightly different speeds. A more advanced masticator, the Banbury mixer, has rotating blades. (EA)

The last step in the preparation of commercial rubber is vulcanization, since the vulcanized rubber cannot be further shaped. Without this treatment, rubber is an unsatisfactory material; it is brittle when cold and sticky or gooey when hot. Goodyear overcame these problems with his vulcanization process. In vulcanized rubber, the polyisoprene chains are cross-linked by disulfide bonds. Several methods of achieving vulcanization are described in EB11. In one, the rubber is immersed in molten sulfur for an hour or so at 140 deg. C. In another, the rubber is placed in a lead chamber with chloride of sulfur. In a third, it is cooked with a solution of calcium polysulfide at 140 deg. C. The use of excess sulfur or heat results in a hard, inelastic rubber (ebonite).

The Microsoft Encarta CD, which is probably available in Grantville, mentions that vulcanization can be accelerated with aniline and thiocarbanilide.

Rubberized cloth can be prepared by dissolving the rubber in one of its solvents ("carbon bisulphide, benzol and mineral naphtha, carbon tetrachloride, and chloroform") and then using the solution to coat the fabric. The original MacIntosh process used naphtha.

The Logistics of Rubber Collection

Most rubber plants require a tropical climate. Once these plants have been located, we have four choices. First, we can simply trade with the natives for it. Second, we can go out into the hinterland and collect the latex from wild plants ourselves. Third, we can establish local rubber plantations. Finally, we can collect the seed (or other propagatable plant materials) and cultivate the plant elsewhere. This could be at a different tropical location (presumably, one more advantageous to USE), or in greenhouses back home.

All of the high-ranking rubber sources listed at the beginning of this essay have been cultivated, at least on an experimental basis. Most have also been transplanted, at least for trial purposes, to another part of the world, e.g., Hevea, Castilla and Manihot to Asia and Africa, Funtumia to Trinidad (Christy, 237) and Asia (EB11), Guayule to the Soviet Union, and the Russian dandelion to the USA.

However, because Hevea is the most important source of natural rubber, it behooves us to take a closer look at why plantations in Asia and Africa have supplanted the collection of wild rubber in Brazil.

Collecting Wild Hevea Rubber

In our timeline, Brazil was not an important source of rubber after 1920. That is because the British successfully transplanted Hevea brasiliensis to Asia. The wild Brazilian rubber was unable to compete with the plantation rubber because its collection was too labor intensive.

There are limits to how much rubber can be collected from wild Hevea trees. They are widely dispersed in the rainforest, usually only two or three trees per hectare (Dean 10). The trees had to be found, and then connecting paths had to be created by hacking through the dense rainforest vegetation with a machete. Usually, a single tapper would clear two or three trails of 60 to 150 trees each. (Dean, 36-37) The tapper traversed one trail each day. In contrast, on a Hevea plantation, one tapper might process 400 trees in a single day (EA).

Large-scale collection of wild rubber was limited by the labor supply. The Amazon jungles were thinly settled, so workers had to be brought in from elsewhere. These strangers were vulnerable to the many diseases and other pitfalls of life in the Amazon, and labor turnover was high. Even in 1907, "each ton cost five lives" (Dean, 44).

In the lower Amazon, and on the coast, where rubber trees were more accessible, yields declined substantially (from ten to two pounds of rubber per tree per year), as a result of overtapping (Brown, 104). The overtapping was evident by 1853, just eight years after the vulcanization process expanded the rubber market (Coates, 58-9). This forced collectors to go deeper into the Amazon, increasing provisioning costs.

In southeast Asia, plantations reduced labor costs, because a single worker could tap more trees in a day. Logically, the Brazilians should have started their own plantations. Unfortunately, even though it is native to the region, and hence well adapted to the local soil and climate, Hevea brasiliensis cannot be successfully cultivated in plantations in Latin America. The Microsoft Encarta Encyclopedia on CD in its "rubber" essay contains these fateful words: "About 99 percent of plantation rubber comes from southeastern Asia. Attempts to establish significant rubber plantations in the tropical zone of the western hemisphere have failed because of widespread tree loss as a result of a leaf blight." (More information about the attempts to establish Hevea plantations in Latin America appears in Appendix 3.)

Even without the South American Leaf Blight, it is doubtful that Brazilian plantations would be competitive with southeast Asian ones. In the early 1900's, the daily cost of labor and provisions in the Orient was perhaps one eighth of that in Brazil (Akers).

Once the demand for rubber outstrips the level that can be produced by wild Hevea brasiliensis trees, it will be essential to establish Hevea plantations elsewhere, to produce rubber from other botanical sources, or to manufacture rubber synthetically.

The Transplantation of Hevea to Asia

Wickham collected about 70,000 seeds in Brazil in 1876. These were planted at Kew Gardens, but only 2,600 germinated. The seedlings were forwarded to Ceylon and thence distributed elsewhere in Asia.

Some of the sites chosen, such as Calcutta, were poorly suited for Hevea. Fortunately, we have the benefit of hindsight; we know roughly where Hevea plantations were successful. For example, that map in CE also shows the major producing areas for plantation rubber in India, Ceylon, Burma, Thailand, and the Malaysian-Indonesian region.

It is also extremely important that all attempts to transplant Hevea be made strictly with seeds, not with cuttings that might carry abroad the deadly fungus.

Moreover, speed is of the essence. EB11 warns that "the seeds readily lose their vitality," and suggests that they should be "loosely packed in dry soil or charcoal." According to Polhamus (273), in the open, the seeds are only viable for seven to ten days, but packed in charcoal or sawdust, they can be expected to germinate if planted within four to six weeks.

Collecting Other Wild Rubbers

Information is limited (and unavailable in 1632), but Treadwell says that in the British Honduras in the twenties, one man working eleven days in fifty acres of jungle could collect 700 pounds of Castilla rubber.

Rubber Plantation Management

Most of Grantville's information concerning rubber tree cultivation relates to Hevea. EA suggests that the Hevea trees be raised in a nursery for one year, then planted outside in rows about 15 to 20 feet apart. It says that, after casualties from disease, accident, and so forth, there are about 150 trees per acre (see also Brown 104). The trees are mature enough to be tapped when they are five to seven years old; tapping can continue for another thirty to forty years. The older trees are more productive.

It will be found that the trees vary in productivity. This variation can be exploited in a number of ways, including cross-breeding and bud grafting. According to CE, "Bud grafting consists of grafting a dormant bud from a proved high-yielding tree to a seedling one to two years old. After several months the bud forms a healthy bud shoot termed a scion, which grows to form the new tree. The seedling is then cut off just above the bud patch." A photograph shows how the foreign bud has been inserted into a "bark flap."

Hevea has been grown in African and Asian plantations alongside other crops, notably cassava, sesame, ground-nuts, tea, coffee, cocoa and tobacco. The EB11 advises against this interplanting, except in the case of cocoa.

The first rubber plantation in southeast Asia raised Ficus elastica (first planted in 1872), because at that time, before Ridley devised his improved tapping scheme, it yielded more rubber than did Hevea brasiliensis (Joshi). The most successful Ficus elastica plantations have been in Asia, in the mountainous districts of Assam, Ceylon and Java. (EB11)

The "Angiosperms" article in the modern EB claims that Funtumia elastica has the advantage that it will grow in parts of tropical Africa which are too dry for Hevea. It nonetheless discourages the cultivation of Funtumia elastica, declaring that it must be grown for twenty years before commercial yields become obtainable. However, this source is plainly in error; Christy's African Rubber provides ample data that Funtumia yields rubber even when it is just five years old, although he recommends that tapping not commence until the next year. It is regrettable that this specialist knowledge will not be available in Grantville, and hence the development of Funtumia plantations in the new timeline may be delayed.

There is only limited information available to Grantville on the cost of production and, of course, the old timeline data is of limited relevance to the hybrid economy created by the Ring of Fire. For what it is worth, EB11 reports that circa 1911, the cost of Ceylonese plantation production was about one shilling a pound, for a field planted at a density of 150 trees an acre. However, another source (unavailable in Grantville) pegs the Asian (Malaysian) plantation cost somewhat lower; just 0.75 shillings a pound. In contrast, the cost of Brazilian rubber was four shillings a pound. (Coates, 156)

The price of rubber was then about 2.5 shillings (US$1.25) per pound.

For Castilla plantation rubber harvesting in northern tropical America in the Twenties, Treadwell says that the cost of production was 25 U.S. cents a pound. (32)

The Geopolitics of Foreign Rubber

One of the problems of developing a post-Ring of Fire (RoF) rubber industry was expressed in an aside to readers by Mike Stearns: "the natural resources were halfway around the world under the political control of other nations . . ." (1633, Chap. 34)

Even the citizens of nations that are allies in Europe (the English and Dutch in the old time line, "OTL") may take advantage of each other elsewhere. This is an era in which the term "cutthroat competition" is taken literally, and there is "no peace beyond the line" defining the bounds of Europe.

Even if you didn't have to worry about the predatory habits of your fellow humans, there is the question of disease. Up-timers are perturbed enough by the public health conditions of down-time Europe, but the rest of the world is worse off. The mortality rates are three to four times higher in the Indian Ocean area, ten times higher in the American tropics, and fifty times higher in West Africa. (Landes, 170)

The New World

Let us first examine the situation in the New World. The Castilla Rubber Tree grows in "New Spain" (in Mexico and Central America) and in "New Castile" (which includes western South America). All of these regions are claimed by Spain. Legally, there is a ban on immigration, and even trade visits, by foreigners. All transatlantic trade leaves from Seville, takes cargoes of manufactured goods to specified colonial ports (Veracruz in Mexico, Portabello in Panama, and Cartagena in Columbia), and brings gold, silver and other American products back to Seville.

Only a Spaniard can buy a licencias de toneladas (the right to ship a certain number of tons of freight on a ship heading out to Spanish America). However, he could be acting as a front man (testaferro) for a foreign merchant. A particular kind of testaferro was the cargadore (the word now means a porter), who actually went on board with the cargo and made sure it was sold for a good price. A foreign merchant could also have a Spanish agent who was a resident of one of the American ports of call for the Spanish trade fleets. Another trick was to sell a foreign ship (with a cargo) to a Spanish figurehead, who would rename it, obtain a sailing license, include it in the Spanish trade fleet, and ultimately sell it back to the original owner (at a price which included a profit on the cargo). (Braudel II, 152-3; Solana) As early as 1608, two-thirds of the shipments to the Indies was of foreign goods (msu.edu).

These practices were geared toward moving foreign manufactures to the Americas, in return for gold and silver. However, a resident testaferro could in theory set up a rubber collection program on behalf of a USE customer. The catch, of course, is that there could be no direct supervision by a non-Spaniard.

Mexico, at least, has some degree of native trade in rubber, probably of Yucatan origin. In the sixteenth century, the Aztecs and Maya used it in making footgear, headgear, game balls, and incense (Shidrowitz, 2-5, 372-3). Hence, a local agent could put the word out that he was interested in rubber products, and expect to see some results. The rubber would have to be shipped overland or by "coaster" to Veracruz.

Of course, dealing with testaferros—not to mention Spanish officials—is going to cut into your profit margins, and it is conceivable that, once they recognize the military importance of rubber, the Spanish government will take pains to prevent the transfer of rubber from Spain to the USE. (Although Spain and the Netherlands happily traded with each other even while Spain was trying to reconquer the latter, and the special taxes which they imposed on trade with the enemy helped finance the war.)

You have the option of ignoring Spanish law and dealing directly with the Indians (or collecting the rubber yourself). If you are caught, you will likely to be tortured and put to death. So, my advice is, don't get caught.

The secret to success is to travel, preferably in fast, well-armed ships, to areas where the Spanish are weak, and where the natives, if any, are hostile to them.

One such area is the eastern half of the Yucatan peninsula.

Some of the Yucatec Maya have been in a state of revolt since 1610. Moreover, an independent Mayan state still exists in northern Guatemala (it wasn't conquered until 1697).

The southeast portion of the Yucatan is essentially uninhabited. Beginning in 1638, it was infiltrated by British logwood cutters. The Spanish attempted to expel the intruders, but in general were not successful, and the region ultimately became British Honduras (Belize).

Another weak point is the Meskito (Mosquito) Coast of Nicaragua. There are no significant Spanish towns or forts in-between Trujillo (Honduras) and the mouth of the San Juan River (which divides Nicaragua from Costa Rica). In fact, in our timeline, the English established a settlement at Cape Gracias a Dios in 1633, and went on to establish an informal alliance with the local Meskito Indians which endured for two centuries. (Perez-Brignoli, 13, 37, 53; Burns, 209, 362-5)

The USE could collect rubber from the Castilla trees in the Yucatan, British Honduras, northern Guatemala, Nicaragua and eastern Honduras. The Indians can be taught how to tap the rubber, and then we can visit them periodically to collect the material. If hostile forces compel us to engage in a quick in-and-out operation, we fell the trees and save seed for replanting in a more secure locale. We can increase our security by allying with the English Puritans on Providencia Island (about 150 miles off the coast of Nicaragua), and by capturing Jamaica (taken by the English in 1655). (Burns, 202-211)

The latex-producing properties of Castilla lend themselves to hit-and-run operations. A single tree can yield a great deal of latex at one tapping, but it can only be tapped one to three times a year. The specialist literature reports that Mexican bandits could steal a half-year's yield in a night, by surreptitious tapping. (Polhamus, 262)

While the Castilla tree is the oldest source of natural rubber, the Para Rubber Tree is the most important commercially. How readily can it be exploited by USE entrepreneurs?

Consulting an atlas, you will see that Para is the name of the province in Brazil which includes the mouths of the Amazon. There is also a map in CE which shows sources of wild rubber in South America. If we compare it with a physical map of the continent, it appears that the best places to look are along the banks of the Amazon proper, as well as near certain tributary rivers: the Rio Negro, Japura, Ica, Putumayo, Jurua, Madeira, and Tapajos. (Some of these may actually be sources of other kinds of wild rubber.)

The difficulties of navigating these waterways is discussed in the EB11 "Amazon" entry, which also calls our attention to "the great india-rubber districts of the Mayutata and lower Beni . . ." It additionally mentions that nineteenth-century rubber traders plied the Negro, the Madeira, and the Purus, that the "finest quality of india-rubber comes from the Acre and Beni districts of Bolivia, especially from the valley of the Acre (or Aquiry) branch of the river Purus," and that 35% of the Amazon Basin rubber is from the province of Para. The rest, presumably, is from the province of Amazonas.

The hazards of this venture are more political than navigational. The Treaty of Tordesillas (1494) sought to avoid conflict between Spain and Portugal in pagan territory, giving most of the Americas to Spain, and reserving Africa, Asia and northeastern Brazil to Portugal. The treaty actually gave the Amazon region to Spain. However, in 1580, the main royal line of Portugal came to an end, and Philip II of Spain became king of Portugal. In consequence, the Spanish rulers allowed the provincial authorities in Lisbon to take responsibility for policing the mouth of the Amazon.

In the late sixteenth century, the Portuguese were preoccupied with northeast Brazil, and the Spanish with Peru and Mexico, permitting the French, Dutch, English and Irish to establish settlements in the lower Amazon (the Dutch at the mouth of the Xingu river, and the English as far as 300 miles upriver). However, in the early seventeenth century, the Portuguese reacted violently to these incursions. They began by establishing the town of Belem, just south of the Amazon, in 1615. Then, during the period 1623-25, they sallied out and destroyed all of the non-Iberian holdings. Even the Catholic intruders were massacred. (Furneaux, 49-51; Smith, 141-2)

A logical question is, why not just send traders to Belem? Unfortunately, this would not be officially tolerated. Prior to 1591, the Portuguese allowed immigration into their colonies by anyone of the Catholic religion. However, after that date, they adopted the Spanish law which excluded all aliens.

Hence, if the USE wishes to trade openly in Belem, or indeed anywhere in Latin America, it must do so through Spanish or Portuguese intermediaries. Spanish agents are fine if you want to use them to arrange shipments of Castilla rubber. However, it is doubtful that they can help you get Para rubber from Brazil. Despite Spanish rule, it is not clear that the Belem authorities will be receptive to Spanish agents.

In 1637, a small Spanish party (two friars and six soldiers), originating in Ecuador, descended the Amazon. One friar was sent to Lisbon for questioning, the rest of the party was detained, and later that year Pedro de Teixeira took a force of over 1,000 men upriver, reaching Quito almost a year later. The obvious purpose of this expedition was to strengthen the Portuguese claim to the Amazon Basin. (Smith, 143-8)

Consequently, to set up a quasi-legitimate rubber collecting operation based in Belem, the USE may need to identify the Portuguese equivalent of the Spanish testaferros. There are conversos (Jews who converted, at least publicly, to Christianity) in Brazil, and the Nasi family may be able to identify possible recruits from this community.

You can avoid this rigmarole if the inhabitants of Belem are willing and able, despite the law, to trade with foreigners. Such illicit trade was common in the Caribbean. The visitors might land a party in a secluded cove, and it would then make surreptitious contact with the locals. They could approach the harbor, and plead that they had been driven off course by a storm. They could "win their market at sword's point"; make a show of force and then, perhaps after real or pretended resistance by the local garrison, receive the governor's license to trade. (The foreigners might even pay duties or license fees.) Or a neglected settlement might welcome them openly, without coercion, as seems to have occurred on Trinidad in the early 1600s. (Naipaul, 60-70; Burns, 142-6)

Even if the local Portuguese are uncooperative, you may be able to infiltrate the Amazon region. Belem itself is at the mouth of the Para, which lies to the south of the Amazon and is not directly connected to it. Hence, in order to discourage further foreign activities on the Amazon, Portuguese also built a new fort at Gurupa (Furneaux, 50), which overlooks the more southerly of the two main entry channels. Nonetheless, it may be possible to sneak into the Amazon by way of the northerly channel, the Canal do Norte.

The odds are improved if we are forearmed with detailed knowledge of its navigational peculiarities. Grantville's maps of the region are probably not particularly detailed, but Dutch sailors did serve from time to time on Portuguese ships, and may have some knowledge of these waters. Or there may be Portuguese mariners who are sufficiently estranged from their native land (perhaps because it is under Spanish rule) to be willing to guide us through.

Unfortunately, the Para rubber trees do not lend themselves to snatch-and-run operations. While they are prolific latex producers, their wound-healing mechanisms assure that only a small amount of latex is extracted on a given day. Nor has it been found to be productive to fell the trees in order to get a "one time" bonanza. So that means lingering in the Amazon, for weeks or months, until one has collected an adequate cargo of rubber. Which, in turn, increases the risk that native allies of the Portuguese will report your presence, guaranteeing that you have to fight your way back to the ocean.

It is safe to say that it is impossible to establish a USE trading post in the lower Amazon, and supply it on a continuing basis by ships traversing the entrance channels, without either obtaining the permission of the king of Spain, or overwhelming the Portuguese military forces in the region.

While you cannot hope to collect a substantial amount of rubber in the lower Amazon without your presence becoming known to the authorities in Belem, a stealth run could be made for the purpose of collecting seeds. However, we then run up against the problem that Hevea seeds have a very short period of viability. Hence, for such a mission, you really want to have a ship with both sails and steam engines. It enters and leaves the river quietly, under sail, and it steams home. (Ocean steamers can navigate the Amazon as far upriver as Iquitos, 2,300 miles from the ocean.) When Wickham needed to collect Hevea seeds for Britain in 1876, he chartered the steamship Amazonia. The "seed raid" is probably impractical prior to the conclusion of the Baltic War.

Another option is to seek out a "back door" into the Amazon basin. The shortest routes are through the Guyanas, the coastal region between Venezuela and Brazil. The stretch separating the mouth of the Orinoco River (Venezuela) and the mouth of the Amazon was known in this period as the "Wild Coast," because of the paucity of European habitation. The Spanish made no effort to settle it, and minimal effort to control it (Hemming, 182-3; Burns, 173).

Of the possible routes, the most interesting one is probably the one exploited in our timeline by the Dutch. Beginning in 1617, they established settlements on the Essequibo River (in British Guyana). They ascended the Essequibo River, then its tributary, the Rupununi, portaged over to the Rio Branco (the Rupununi savannah is flooded over during the rainy season), and then sailed on to the Rio Negro, the Amazon, and the Madeira. Once in the Amazon basin, they traded in iron and slaves. In OTL, the Portuguese eventually blocked this traffic, first with a fort at Manaus (1667), and later with a mission at the mouth of the Rio Branco (1720). (Furneaux, 51; Guyana.org; Burns, 173-6, 196, 214)

The EB11 entry for "Guiana" warns, "The Essequibo can be entered only by craft drawing less than 20 ft. and is navigable for these vessels for not more than 50 m., its subsequent course upwards being frequently broken by cataracts and rapids." So, if we use this route to trade for rubber, much of the traveling would have to be done by canoes. This would result in much higher transportation costs and longer transportation times than if we could take full advantage of the Amazon River.

There are alternative routes which look shorter on paper, but are less likely to be practicable. For example, one could ascend the Maroni and Litani Rivers (the border between Suriname and French Guyana), and portage over to the Paru or the Jari tributaries of the Amazon, but that requires crossing the Tumucumaque Mountains.

These routes also allow you to play "Johnny Rubber Seed": collect Hevea seeds in the Amazon basin; plant them on your return trip, at a marked location, while they are still viable; and come back four years or so later to collect the seeds from your transplants. Eventually, you will get the seeds to the coast and onto a ship.

It is not strictly necessary to cross the Guyana Highlands into the Amazon Basin in order to find rubber trees; there are some in the Guyanas. These are not the famous Hevea brasiliensis, but another Hevea species, Hevea guianensis. Hence, USE exploration of the Guyanas could be somewhat improvisational; we try to use the river system to reach the Amazon Basin, but if we find rubber trees along the way, we exploit them.

The third possible source of natural rubber in the New World is the Ceara Rubber Tree (Manihot glaziovii). "Ceara" is the name of a province in northeast Brazil (the part that bulges toward Africa). Ceara was pretty much ignored by Europeans prior to 1649. However, USE exploration in that region could attract the attention of the Dutch and Portuguese, who are struggling for control of the sugar plantations farther south. The plant we are seeking is native to the sertao (the arid highlands), and hence may also occur in the hinterland of Rio Grande del Norte, Paraiba, Pernambuco and Bahia (the first two are confirmed by Polhamus, 51). Keep your distance from Bahia and Recife if you don't want to be drawn into the Dutch-Portuguese war.

We only have a written description of the Pernambuco Rubber Tree (Hancornia speciosa), and it occurs in the very region that the Dutch and Portuguese are fighting over. If this rubber enters commerce, it most likely will be the result of their own activity.

Finally, there is guayule (Parthenium argentatum). This occurs in the Chihuahua desert region of Mexico and Texas, and was used during World War II as an emergency source of rubber. This desert is the largest one in North America, covering over 200,000 square miles, and including parts of modern Mexico, Arizona, New Mexico and Texas. There is a map in Collier's Encyclopedia (CE) which shows where guayule is found in the wild.

The easiest route into the region is by way of the Rio Grande river. Unfortunately, there are Spanish settlements on the river, at San Juan Bautista and El Paso del Norte, as well as to the south, at Janos, Chihuahua, Parral and Monclova (Spanish Bannon, 4). Hence, the least protected route would be from the northwest, through Apache and Comanche territory. Even to reach that territory, you will have to make a long journey, most likely up the Llano River and then south.

Since you could not expect to make this journey repeatedly without interdiction by Spanish forces, you would mostly like want to do it just to gather seeds and seedlings for transport to a safer region, perhaps one of the Caribbean islands, or somewhere in Africa or in Italy.

Asia

The position of Asia in the natural rubber industry is a curious one. While there are native rubber-producing plants, OTL Asian rubber production is mostly based on the transplanted Hevea brasiliensis. The up-timers have a great advantage over their late-nineteenth-century forebears; they know where Hevea production was most successful. The ...