85 



The only other American rubber of importance, at present, is yield- 

 ed by Castilloa elastica. It appears on the market in a number of dif- 

 ferent forms under the names of Mexican, Nicaraguan, etc. As tar as 

 we know C. elastica is the only species of the genus yielding rubber, for 

 the C. Markhamia of Collins turns out to be a Perebea species.}: 



The latex is obtained in a rough and ready fashion by hacking a 

 spiral channel from the crown of the tree to the ground, or by making 

 great gashes with a machete. 



Collins § has recommended a timber-scoring knife for tapping, and 

 since then most writers have followed his lead. On experimenting with 

 one, I found it was practically useless, as little latex exuded, possibly 

 owing to the closure of the vessels by the drag of its edge. Stabbing 

 with a broad-bladed knife, or with a chisel as practised in Ceylon, § 

 gives good result without much damage to the tree. In the previously 

 mentioned article in the "Trinidad Bulletin" (1898), there is some 

 slight confusion as to the localities suitable for the growth of Castilloa. 

 In one place (p. 122), "it will scarcely thrive in regions that are not 

 equally suited to Hevea spp" which (p. 1»30) grow " on land which is 

 periodically inundated, even to a depth of five feet." Then (p. 121), 

 " the tree {Castilloa) avoids marshy or boggy land, and manifests a 

 preference for warm deep loam, or sandy soil/' The latter statement is 

 the correct one. 



The most general method of preparation in Mexico is to add an 

 extract of the leaves and stem of the moon-flower (Ipomoea bona-nox), 

 and allow the mixture to stand over-night. The floating clot which 

 forms is then pressed to remove some of the water.lf As in all these 

 cases of preparation bv " wet " methods the rubber contains large quan- 

 tities of water, it lu-es from twelve to thirty per cent, on drying. 

 Another method is in use in Nicaragua.* The latex is mixed with 

 about three parts of water, and allowed to stand over-night, when the 

 rubber comes to the surface in particles which do not unite to form a 

 solid mass. The water is then drained off from below, and the rubber 

 particles are mixed with a fresh supply of Water, and the process is 

 again repeated. The particles are then brought into a solid mass by 

 pressure. The latest account of this method is apparently given by 

 Hart, in an article on the " Coagulation of Rubber,"** who appears to 

 have rediscovered it. I quote it in full as I may be mistaken. " After 

 the addition of water the mixture is well shaken ; the globules of rubber 

 (having a lighter specific gravity than the albumenoids and proteids 

 [sic] contained in the latex) will float quickly to the surface. It is 

 found moreover that on the addition of further volumes of water and the 

 removal of albumenoid liquors from below the floating rubber, the 

 globules rise much more quickly to the surface." 



X " Kew Bulletin," 1887, xxviii p. 13, cf. " Trinidad Bulletin," 1898, p. 21. 

 $ Collins " Report on Caoutchouc." 



II " Royal Botanical Gardens, Ceylon," 1898 j Ser. L, No. 4, p. 30 

 1T Belt. " Naturalist in Nicaragua," p. 33. Morris, " Colony of British 

 Honduras," p. 76. 



*° "Le Caoutchouc," &c., p. 62. " Kew Bulletin," 1887, xxviii., p. 16. 

 " Trinidad Bulletin." 1898, p. 131. 



