﻿NATURAL 
  RUBBER 
  — 
  COOK 
  385 
  

  

  disintegration 
  naturally 
  gave 
  the 
  impression 
  that 
  Castilla 
  rubber 
  is 
  

   inferior 
  to 
  Para 
  rubber, 
  though 
  in 
  reality 
  no 
  difference 
  has 
  been 
  estab- 
  

   lished 
  by 
  comparison 
  of 
  material 
  not 
  affected 
  by 
  the 
  enzyme. 
  

  

  Since 
  most 
  of 
  the 
  rubber 
  that 
  reached 
  Europe 
  and 
  the 
  United 
  

   States 
  in 
  the 
  time 
  of 
  Goodyear 
  came 
  from 
  the 
  Castilla 
  tree, 
  the 
  tend- 
  

   ency 
  to 
  become 
  sticky 
  was 
  often 
  supposed 
  to 
  be 
  a 
  general 
  quality 
  of 
  

   rubber. 
  Thus 
  Goodyear's 
  efforts 
  to 
  develop 
  a 
  treatment 
  of 
  rubber 
  

   that 
  would 
  keep 
  it 
  from 
  becoming 
  sticky, 
  the 
  efforts 
  that 
  led 
  to 
  the 
  

   accidental 
  discovery 
  of 
  vulcanization, 
  hark 
  back 
  to 
  the 
  enzyme. 
  When 
  

   Para 
  rubber 
  from 
  Brazil 
  proved 
  not 
  to 
  be 
  sticky, 
  it 
  was 
  naturally 
  con- 
  

   sidered 
  a 
  superior 
  kind. 
  

  

  That 
  some 
  of 
  the 
  Castilla 
  rubber, 
  even 
  in 
  the 
  early 
  days, 
  was 
  not 
  

   sticky, 
  may 
  be 
  inferred 
  from 
  the 
  extent 
  to 
  which 
  rubber 
  was 
  being 
  

   used 
  in 
  England 
  and 
  America 
  before 
  Goodyear's 
  discovery 
  was 
  made. 
  

   Even 
  the 
  uses 
  of 
  rubber 
  among 
  the 
  Indians 
  of 
  Mexico 
  and 
  Central 
  

   America 
  would 
  not 
  have 
  developed 
  with 
  a 
  sticky 
  material. 
  The 
  In- 
  

   dians 
  knew 
  how 
  to 
  treat 
  the 
  rubber 
  to 
  keep 
  it 
  from 
  becoming 
  sticky, 
  

   by 
  spreading 
  the 
  latex 
  in 
  thin 
  layers 
  on 
  large 
  leaves 
  and 
  exposing 
  it 
  

   on 
  open 
  ground 
  to 
  the 
  heat 
  of 
  the 
  sun, 
  thus 
  destroying 
  the 
  enzyme. 
  

   The 
  native 
  procedure 
  in 
  coagulating 
  the 
  Castilla 
  rubber, 
  witnessed 
  

   and 
  photographed 
  in 
  the 
  Soconusco 
  district 
  of 
  southwestern 
  Guate- 
  

   mala 
  in 
  1902, 
  was 
  described 
  and 
  illustrated 
  in 
  the 
  bulletin 
  of 
  1903. 
  

   The 
  samples 
  of 
  Castilla 
  rubber 
  prepared 
  by 
  the 
  native 
  "uleros" 
  re- 
  

   mained 
  in 
  good 
  condition 
  for 
  more 
  than 
  20 
  years, 
  as 
  little 
  affected 
  by 
  

   age 
  as 
  samples 
  of 
  Para 
  rubber, 
  showing 
  that 
  the 
  treatment 
  had 
  been 
  

   completely 
  effective 
  in 
  destroying 
  the 
  enzyme. 
  Samples 
  from 
  washed 
  

   latex 
  seemed 
  to 
  deteriorate 
  even 
  more 
  rapidly 
  than 
  others, 
  perhaps 
  

   because 
  the 
  enzyme 
  was 
  more 
  thoroughly 
  distributed 
  among 
  the 
  rub- 
  

   ber 
  particles. 
  It 
  was 
  known 
  already 
  that 
  an 
  enzyme 
  was 
  responsible 
  

   for 
  the 
  deterioration 
  of 
  the 
  Castilla 
  rubber, 
  and 
  that 
  the 
  enzyme 
  

   could 
  be 
  destroyed 
  simply 
  by 
  heating 
  the 
  latex, 
  as 
  published 
  by 
  Parkin 
  

   in 
  1900, 
  in 
  the 
  Annals 
  of 
  Botany. 
  

  

  Although 
  the 
  demand 
  for 
  rubber 
  increased 
  more 
  rapidly 
  after 
  

   Goodyear's 
  discovery 
  was 
  made, 
  the 
  previous 
  century, 
  between 
  La 
  

   Condamine 
  and 
  Goodyear, 
  had 
  witnessed 
  a 
  gradual 
  advance. 
  The 
  

   properties 
  and 
  uses 
  of 
  rubber, 
  largely 
  in 
  waterproofing, 
  furnished 
  the 
  

   last 
  chapter 
  on 
  "Vegetable 
  Substances" 
  in 
  the 
  "Library 
  of 
  Entertain- 
  

   ing 
  Knowledge," 
  published 
  at 
  London 
  in 
  1833, 
  concluding 
  with 
  a 
  

   statement 
  of 
  imports 
  and 
  prices. 
  

  

  More 
  than 
  fifty-two 
  thousand 
  pounds 
  of 
  caoutchouc 
  were 
  imported 
  into 
  England 
  

   in 
  1830, 
  being 
  nearly 
  double 
  the 
  quantity 
  brought 
  during 
  the 
  preceding 
  year. 
  

   The 
  consumption 
  for 
  the 
  year 
  ending 
  April 
  5, 
  1833, 
  is 
  stated 
  at 
  178,676 
  lbs. 
  Its 
  

   price 
  is 
  from 
  Is. 
  6d. 
  to 
  2s. 
  3d. 
  per 
  lb.; 
  the 
  duty 
  upon 
  it 
  being 
  5d. 
  per 
  lb. 
  The 
  

   increase 
  in 
  the 
  demand 
  is 
  to 
  be 
  ascribed 
  to 
  the 
  application 
  of 
  the 
  substance 
  as 
  

   an 
  article 
  of 
  general 
  utility. 
  

  

  