The Grantville Gazette Volumn VI by Eric Flint
The up-timers don't know which parts of the milkweed plant have the highest rubber content, so they will have to find this out by trial and error. The leaves provide more rubber than the stems; yellowing leaves provide more than young leaves, and autumn leaves provide more than spring or summer leaves.
Milkweed latex has a fairly high resin content (perhaps 9-23%). Several methods of recovering the rubber were developed in the old timeline. Kassner treated the latex first with benzene or carbon disulfide, and then with alcohol and caustic lye. After each solvent addition, he distilled. The rubber was the final residue. Hall and Long used boiling acetone, followed by boiling benzene. Students in a modern introductory organic chemistry lab used acetone to extract various impurities and then cyclohexane to extract the rubber. (Whiting, 20-23; Volaric)
None of this will be known in Grantville. Up-timers will probably first try a simple hot water treatment of chopped-up plant material. If they don't like the properties of the rubber, they will probably then just experiment with different solvents until they get results that they like.
Of course, organic solvents are going to be in short supply until we can extract the necessary compounds from coal or oil. The most readily available organic solvents will be ethanol and acetic acid. And any solvent treatment step is going to increase production costs.
It may be possible to cure the resin content problem at its source by breeding milkweed for low resin content (this of course assumes that you have a way of measuring resin content!). I have also come across a hint that in the 1930's, the Russians found a method of chemically treating the plant so that it produced latex with more rubber and less resin. (Whiting, 18)
Goldenrod
Thomas Edison devoted the last four years of his life (1927-31) to an attempt to develop a method of producing rubber from domestic plants. Edison ultimately settled on the goldenrod, because "it would grow in most parts of the country, it grew to maturity in just one season, and it could be harvested by machines." He increased goldenrod rubber production several-fold by breeding methods, although his technique was not "cutting edge" (Vanderbilt 316) and could certainly be improved upon by a modern breeder with access to a variety of material.
Goldenrods originated in Europe. There are about two dozen species of goldenrods found in the wild in West Virginia, and thus, presumably, in the land transported by the Assiti shard. Since goldenrod is an ornamental plant, there may be additional varieties in Grantville gardens. We can collect the latex from as many different species as we can find, and decide which species is the best rubber producer. Edison preferred Solidago rugosa and Solidago leavenworthii, but this would not be known in Grantville. Nor will anyone know what to expect in terms of yield, unless someone has an informative Edison biography in his or her personal library. (Edison's results are set forth in Table 2.)
Likewise, it will be necessary to reinvent the methods developed by Edison for harvesting the plants (he wanted to just collect the upper leaves, since they have the highest rubber content) and for recovering the rubber from the latex (he used acetone to pull out the resin, and then benzene or benzol to extract the rubber). The solvents can be recycled. (Baldwin, 398; Vanderbilt, 313)
My thinking is that goldenrod will be grown and harvested primarily as a source of yellow dye, with any rubber production being strictly a bonus. The trick will be to identify a variety that is a good dye source and a good latex source.
Rubber Reclaiming
In 1910, when the price of rubber was high, about half of all of the rubber sold was reclaimed. (Reschner)
Rubber is going to be in high demand, and the only immediately available source of rubber is scrap rubber. Since more than half of all modern rubber goes into tires, the latter are also the foremost source of scrap. An automobile tire weighs about twenty pounds. Of this, about 60% is recoverable rubber. (tfhrc.gov). A truck tire weighs twice as much as an automobile tire, and has a proportionate rubber content.
The residents of Grantville are likely to look first at tires that have been discarded or set aside. These may be in dumps, landfills, garages, backyards, and so forth. The rule of thumb is that modern Americans generate scrap rubber at a rate of one passenger tire equivalent per person per year.
Unfortunately, there is a catch. Grantville is based on the real town of Mannington, West Virginia . . . and its dump was not within the Ring of Fire (Boatright, Grantville Gazette, Vol. 1). So we have to hope that the GV residents were not efficient about setting out their used tires for pickup.
There may also be small amounts of rubber that can be recovered from rubber goods that are no longer useable for their original purpose. Personally, I think that is going to be a real small supply.
Hence, at a relatively early stage, the USE will need to decide whether to scrap some of the auto tires (figuring that it cannot keep the whole auto fleet running) in order to supply patch material for the heavy tires used in the USE's military vehicles.
At the very least, all the spare auto tires in the car trunks can go to the rubber reclaiming plant. If there are around 1,200 cars (Mannington actually has more than that), then that will potentially yield 24,000 pounds of tires, and about 14,000 pounds (seven tons) of somewhat degraded rubber. If we decided to take the working tires off half those cars, that would be another 48,000 pounds of tires, and thus another fourteen tons of secondhand rubber.
One problem is that the Grantville encyclopedias are not very specific about the methods used for rubber reclaiming. EA suggests that the rubber is mechanically reduced to scrap, which is then "heated with steam in the presence of strong chemicals, mainly alkali or acids."
If someone does have the Microsoft Encarta on CD, that gives additional information. It mentions the Chapman Mitchell process, in which hot sulfuric acid is used to destroy tire fabric and restore rubber plasticity, and the Marks "alkaline-recovery process."
In general, the rubber is not going to be restored to its original unvulcanized state, and hence it is more difficult to use. Usually, the reclaimed rubber is used as an extender, together with fresh rubber.
Proposal
Our initial natural rubber industry development strategy should be:
(1) Use rubber substitutes (e.g., leather) whenever possible;
(2) Conserve and reclaim up-time rubber;
(3) Cultivate milkweed at home;
(4) Send raiding parties into Central America to collect Castilla rubber; and
(5) Attempt to reach the Hevea rubber of the Amazon by a back-door route.
Once we have built enough steamships (warships as well as merchant ships) so we can spare a few for extra-European ventures, we should send an expedition-in-force to the Amazon to collect Hevea seeds, and then one to Africa or Asia to establish plantations and collect wild rubber (and rubber tree seeds). Ideally, we would also have sufficient medical resources so as to offer this expedition some protection against the many diseases that hamper seventeenth-century international trade.
If we are allowed to trade freely for wild Brazilian Hevea rubber, and to promote efficient tapping practices, it should satisfy our needs for rubber up until annual world consumption reaches the 30,000 to 40,000 pound range (the peak Brazilian wild rubber production). After that, the development of alternative rubber sources is essential. Hence, at the end of the first decade, we need to decide whether to establish Hevea plantations in Africa or southeast Asia, or to pursue synthetic rubber.
While an investment in the rubber industry is definitely going to qualify as one of USE's riskier commercial ventures, investors can at least be confident that if they are successful, the USE government and private industry will be sitting on their doorstep, anxious to do business.
Table 1: Listed Rubber Sources: Where and How to Find Them
Rubber Plant (Note A)
Range: Range (to extent known in Grantville); Descriptive Material (as available in Grantville (Note B)
Hevea brasiliensis
Para Rubber Tree (major
(Often confused with other producing Hevea species, such as H. guianensis, H. benthamiana, H. pauciflora; H. spruceana is a poor producer.)
Range: W: South America (EA). Range depicted in CE (probably includes other Hevea species). C: Sri Lanka, Malay Archipelago (EA), Straits Settlements, Malay States, Ceylon, Java, Sumatra, Borneo, Burma, south India, West Africa (especially Gold Coast), Congo, tropical Australia (EB11) Range depicted in CE and WBE. There are reports of Hevea paucifolia [sic, pauciflora] and guianensis in British and French Guiana, respectively (EB9)
Descr: EB11 has 1/4 scale drawing of leaves, fruit and seeds; photo of plantation trees; text. EB9 has scale drawings of leaves, male and female flowers, ripe fruit, and seed.
Manihot glaziovii
Ceara or Manioba Rubber Tree
Range: W: Brazil (EA): Northeast Brazil (EB11). Ceara is province of modern Brazil.
C: Ceylon, India (Madras), West Africa, East Africa, Nyasaland, Mozambique (EB11)
Descr: EB11 has scale drawings of branch with flowers, fruit, seeds; photo of tree; text. EB9 has drawings of tree, young leaf, inflorescence, half-ripe capsule, male and female flowers, seed, and seed section.
Castilla elastica
Panama, Castilla, or Ule Rubber Tree
(Other Castilla species produce rubber, e.g., C. ulei.)
Range: W: tropical America (EA); Costa Rica, Guatemala, Honduras, Mexico, Cuba, Haiti, Panama, Nicaragua and, in South America, west of the Andes, especially Peru (EB11) and Ecuador (EB9). Mexican occurrence depicted in CE.
C: West Indies (esp. Trinidad and Tobago), south India, Ceylon, East and West Africa, Nyasaland (EB11)
Descr: EB11 has scale drawing of leaf, twigs with male and female flowers, seed; photo of tree; text. EB9 has drawings of young leaf, seeds, margin of leaf, female flower. EA has description under "Castilla Rubber Tree."
Ficus elastica
Rambong, Assam or Indian Rubber Tree
Range: W: Southeast Asia (EA); India, Ceylon, Sumatra and Java, Burma, Malay archipelago (EB11)
C: West Africa and Egypt ("but not very successful" in Africa). Also an ornamental in Europe.
Descr: EB11 has scale drawing of leaves on twig; photo; text. EA has description under "Rubber Plant."
Funtumia elastica
Lagos, African or Silk Rubber Tree (F)
Range: W: central regions of east and west Africa (Uganda to Sierra Leone). Range depicted in CE and WBE. C: Gold Coast, south Nigeria.
Descr: EB11 has scale drawing of twig with flowers, underside of leaf, fruit; photo of tree; text.
Rubber Vines (EA, CE, EB11)
Range: W: Africa (EA) Africa and Asia (EB11, see note D below)
Descr: EB11 has scale drawing of twig with flowers, fruit. (For the African Landolphia owariensis)
Parthenium argentatum
Guayule (EA, CE, EB11)
Range: W: Mexico and Texas, Chihuahuan Desert (EA). Range depicted in CE.
Descr: text (EA, "Guayule")
Raphionacme utilis Ecanda
Range: W: Portuguese West Africa.
Descr: None, but "Ecanda" may be the native name.
Bleckrodea tonkinensis
Range: W: Tonkin (EB11)
Descr: None, except that it is a large tree.
Hancornia speciosa
The Pernambuco or Mangabeira Rubber Tree,
Range: W: the plateau region (3,000 to 5,000 ft. above sea level), from Pernambuco to Rio de Janeiro, in Brazil. (EB11)
Descr: text.
Sapium species
Range: W: Columbia and Guiana, especially S. jenmani of Guiana (EB11).
Descr: just "large trees resembling Hevea."
Taraxacum kok-saghyz
Russian Dandelion (EA, CE)
Range: W: Turkestan (EA)
Descr: none, but similar to common dandelion.
Solidago
Goldenrod (CE)
Range: Familiar American plant.
Asclepias syriaca
Common Milkweed
Range: Familiar American plant.
Table 2: Productivity of Identifiable Rubber Plants
Rubber Plant (Note A)
Collection: Methods
Density: (Trees per Acre, Tr/Ac); Age in years to First Tapping (y)
Yield/Tree: Rubber, pounds per tree per year
Yield/Acre: Rubber, pounds per acre per year (Note C)
Hevea brasiliensis
Para Rubber Tree (major source in OTL). (Often confused with other producing Hevea species, such as H. guianensis, H. benthamiana, H. pauciflora; H. spruceana is a poor producer.)
Collection: Incision tapping by Ridley method on alternate days (56 g latex per tap)[EA]; V-, herringbone or spiral cuts [EB11], Felling is ineffective for rubber collection.
Density: W: tap at 10-15y [EB11]1 Tr/Ac [Dean10], C: 150 Tr/Ac; tap 6-7y [EB11]; 150 Tr/Ha; tap at 5-7y, productive for 30-40 more yrs. [EA]; 100 Tr/Ac [Enc]; 100 Tr/Ac [WBE];
Yield/Tree: W: 10-15 [EB11]; 2-10 [Dean 10], C1910: 1-2 [EB11]; 0.41-6.76 (6-12 yrs, Malaysia and Ceylon)[Br 126-7]; C1920: 5 [TW301]; CM: 6 [EA]; 4-5 "ordinary" or 12-16 "selected and bud grafted" [CE];
Yield/Acre: W:2-15 [Calc, EB11+Dean], C1900: 382* kg/Ha [EB], C1910: 128-221 (6-7 yr., Malaysia) 105-200 (Ceylon) 105-768 (6-12 yr., combined), [Br126-7] C1940: 342-513* [PH273]; CM: 800-1,000 (avg), 2000+ (top) [EA]; 400-2,000-3,000 [Enc];1,800[WBE]; 798-2,280* [PH273]
Manihot glaziovii
Ceara or Manioba Rubber Tree
Collection: Tapping
Density: tap at 5y [EB11]; 700+ Tr/Ac [PH267]; 320 Tr/Ac [Br150-1]
Yield/Tree: 1+ [EB11]
Yield/Acre: C: 88-176 Germ E Africa (5-8 yr.)[Br150-1]
Castilla elastica
Panama, Castilla, or Ule Rubber Tree
(Other Castilla species produce rubber, e.g., C. ulei.)
Collection: Incision tapping [EA]; herringbone or spiral cut [EB11]; or felling [PH16]; 1-4 taps/y [PH102]
Density: tap at 6y [PH109] 8y [PH104]; 50 [PH267] or 100-120 Tr/Ac [PH109]; 400-700[TW32]; 200/Ac [TW279]
Yield/Tree: W:12[PH93]; 40 [EB11](tree killing tap?), C:0.93-1.01* [PH109], 0.1-1.1*/tap [Br222], 0.38-1/tap [TW150], 0.1-0.4 (6-10y)[TW279]; 0.13/tap [TW32], Felled Tr: max 100 [PH16] 51-73* [PH109]; avg 15-20 [TW148]
Yield/Acre: C:50 [TW279]
Ficus elastica
Rambong, Assam or Indian Rubber Tree
Collection: Shredding of leaves and shoots [EA]; tapping [EB11]
Density: 50 Tr/Ac [PH267]; tap @10y[EB11], can't tap each yr. [Br233]
Yield/Tree: C: 5-10 [EB11], 0.65-2.3 [Br232]
Yield/Acre: C: 500-1,000 [calc]; but 13-52 [Br232]
Funtumia elastica
Lagos, African or Silk Rubber Tree (F)
Collection: Incision tapping, herringbone [EB11]
Density: tap at 20y [EB]; at 5y [Ch193]; tap 2-3 times/y [Ch161]; tap 1-2/y [Br161], W: up to 150-250 Tr/Ac [Ch36]; C1910: 450-600 [Ch97]
Yield/Tree: Tapped (3/yr) 0.19@5y, 0.56@ 8y, 0.94@10y [Ch161]; ~1/tp [Br176] Felled Tr:0.64 [Ch161] 4.5-6.5[Br176]
Yield/Acre: W: ~150-375 [150-250 x 2-3 *.5] C: ~450-900 [450-600 x 2-3 *.5]
Rubber Vines (EA, CE, EB11)
Collection: Cut stems; or macerate roots or rhizomes in hot water [EB11]
Density: ?
Yield/Tree: 6-7/Pl [PH40]; 0.06-0.18/Pl [Br197]
Yield/Acre: ?
Solidago
Goldenrod (CE)
Collection: harvest and extract resin with acetone and rubber with benzol [PH268]
Density: 10-20,000 Pl/Ac [PH268]
Yield/Tree:
Yield/Acre: C: 100 in 1929, >300 in 1934 [Van293-300; Bal398, 411]
Asclepias syriaca
Common Milkweed
Collection: harvest and extract
Density: 10-20,000 Pl/Ac [PH268]
Yield/Tree:
Yield/Acre: C1940: 114-171* [Whiting]
Productivity of Trees for Which De
Hancornia speciosa
The Pernambuco or Mangabeira Rubber Tree,
Collection: Incision Tapping (8 oblique cuts all around trunk)[EB11]
Density:
Yield/Tree:
Yield/Acre:
Parthenium argentatum
Guayule (EA, CE, EB11)
Collection: Shredded; leached with hot water [EA]
Density: C: 3-5y [EA];4-5y [Van284]; 5-9y [PH233]; 8,000-16,000 Pl/Ac [PH267];7,000-11,000 Pl/Ac (Van284, 308)
Yield/Tree:
Yield/Acre: C: 137-241 [PH233], 325-400 [Van284]
Taraxacum kok-saghyz
Russian Dandelion (EA, CE)
Collection: Shredded; leached with hot water[EA]
Density:
Yield/Tree:
Yield/Acre: C1940: 285 (Suomela)
Notes to Tables 1 and 2:
(A) With the exception of milkweed, the cited plant names appear in the Encyclopedia Americana (EA), the modern Encyclopedia Britannica (EB), the Eleventh (EB11) or Ninth (EB9) editions of the Encyclopedia Britannica, the World Book Encyclopedia (WBE), or Collier's Encyclopedia (CE) as sources of rubber.
There are three plants which produce nonelastic rubbers which can be used for insulation, belting, etc. Trees of the genera Palagium and Payena, found in the Malay Archipelago, produce gutta percha. Manilkaea bidentata, found in tropical America, produces balata. Manilkaea zapota, the Sapodilla Tree of Mexico and Central America, produces chicle (mostly used in chewing gum). (EA)
(B) The wild (W) and cultivated (C) range information is primarily from EA and EB11. Info on sites of cultivation includes experimental plantings which may not ultimately have proven successful. Descriptions of the plants are from EB11, unless otherwise stated.