Alum is/was used (as an alternative to heat, sulphur compounds, etc.) to cure (vulcanize) rubber. I can imagine alum-vulcanized rubber->alum, then having that generalized to all cured rubber (the way a "tin" can be made of steel or aluminum), but of course without evidence it's just a story.
FWIW, a 1900 book on rubber products identifies jebe as a specific variety of Brazilian rubber: "Fine Para; Seringa fina called by the natives Borracha or Jebe."
There's also a lower-quality variety called Sernamby de Jebe (or de Borracha), whose common name, Cabeça de negro, has an unsurprising but no longer socially acceptable English translation. (From context, it looks like sernamby must mean something spherical, since it gets paired up with names referring to balls or heads.)
Peru didn't produce jebe at all, but caucho (or simply "Peru".)
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momijizukamori
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Date: 2013-01-05 05:20 am (UTC)FWIW, a 1900 book on rubber products identifies jebe as a specific variety of Brazilian rubber: "Fine Para; Seringa fina called by the natives Borracha or Jebe."
There's also a lower-quality variety called Sernamby de Jebe (or de Borracha), whose common name, Cabeça de negro, has an unsurprising but no longer socially acceptable English translation. (From context, it looks like sernamby must mean something spherical, since it gets paired up with names referring to balls or heads.)
Peru didn't produce jebe at all, but caucho (or simply "Peru".)
http://books.google.com/books?id=OytJAAAAIAAJ&dq=jebe%20alum%20rubber&pg=PA74