﻿362 
  0. 
  JBarus 
  — 
  Solution 
  of 
  Vulcanized 
  India 
  Rubber. 
  

  

  5. 
  Solution 
  in 
  turpentine. 
  — 
  In 
  case 
  of 
  the 
  elastic 
  rubber 
  (a), 
  

   complete 
  solution 
  is 
  at 
  once 
  effected 
  at 
  200°, 
  whereas 
  at 
  ordi- 
  

   nary 
  temperatures 
  the 
  time 
  necessary 
  is 
  enormous, 
  if 
  indeed 
  

   the 
  solutions 
  in 
  the 
  two 
  cases 
  be 
  the 
  same. 
  The 
  syrupy 
  liquid 
  

   obtained 
  at 
  200° 
  seems 
  to 
  dry 
  in 
  very 
  thin 
  films. 
  Special 
  

   experiments 
  made 
  at 
  160° 
  showed 
  that 
  no 
  reasonably 
  speedy 
  

   solution 
  takes 
  place 
  even 
  in 
  liquid 
  turpentine 
  at 
  this 
  tempera- 
  

   ture, 
  thus 
  corroborating 
  the 
  inferences 
  of 
  §§1, 
  2, 
  3. 
  Gray 
  

   rubber 
  (b) 
  is 
  acted 
  on 
  with 
  greater 
  difficulty 
  at 
  210°. 
  The 
  

   solution 
  leaves 
  a 
  white 
  glossy 
  stain 
  which 
  hardens. 
  Pressure 
  

   need 
  not 
  exceed 
  5 
  atm. 
  

  

  6. 
  Solution 
  in 
  chloroform 
  and 
  carbon 
  tetrachloride., 
  — 
  Elastic 
  

   sheet 
  rubber 
  (a) 
  dissolves 
  at 
  once 
  in 
  liquid 
  CHC1 
  3 
  at 
  210°. 
  

   Pressure 
  should 
  exceed 
  15 
  atm. 
  and 
  need 
  not 
  be 
  larger 
  than 
  

   25 
  or 
  30 
  atm. 
  Solutions 
  of 
  any 
  degree 
  of 
  viscosity 
  seem 
  to 
  be 
  

   obtainable. 
  They 
  dry 
  at 
  once 
  on 
  exposure 
  to 
  air, 
  leaving 
  a 
  

   hard 
  residue 
  relatively 
  dark 
  in 
  color. 
  Possibly 
  this 
  was 
  due 
  to 
  

   the 
  presence 
  of 
  sulphur 
  in 
  the 
  chloroform. 
  § 
  15. 
  Gray 
  rub- 
  

   ber 
  (b) 
  is 
  attacked 
  with 
  decomposition 
  of 
  the 
  solvent 
  and 
  evo- 
  

   lution 
  of 
  gas. 
  

  

  , 
  7. 
  Solution 
  in 
  aniline. 
  — 
  Solution 
  in 
  the 
  liquid 
  at 
  200° 
  takes 
  

   place 
  at 
  once, 
  in 
  case 
  of 
  elastic 
  rubbers 
  (a). 
  Pressure 
  need 
  not 
  

   exceed 
  a 
  few 
  atmospheres. 
  Thin 
  films 
  apparently 
  dry 
  on 
  long 
  

   exposure. 
  

  

  8. 
  Solution 
  in 
  animal 
  oils. 
  — 
  Neither 
  in 
  the 
  case 
  of 
  sperm 
  

   oil, 
  nor 
  of 
  lard 
  oil 
  was 
  the 
  elastic 
  rubber 
  (a) 
  dissolved 
  on 
  

   removing 
  from 
  the 
  piezometer. 
  Both 
  disintegrated 
  on 
  stand- 
  

   ing, 
  to 
  a 
  solution, 
  often 
  with 
  slow 
  evolution 
  of 
  gas. 
  

  

  9. 
  Treatment 
  with 
  glycerin. 
  — 
  A.t 
  200° 
  no 
  solution 
  occurs. 
  

   Gly 
  colic 
  alcohols 
  were 
  not 
  examined. 
  Cf. 
  § 
  12. 
  

  

  10. 
  Solution 
  in 
  benzol 
  and 
  higher 
  aromatic 
  hydrocarbons. 
  

   — 
  The 
  elastic 
  sheet 
  rubber 
  (a) 
  dissolves 
  at 
  once 
  in 
  liquid 
  C 
  6 
  H 
  6 
  

   at 
  200°. 
  Pressure 
  should 
  exceed 
  7 
  atmospheres, 
  but 
  need 
  never 
  

   be 
  higher 
  than 
  30 
  atm. 
  The 
  solution 
  exposed 
  to 
  air 
  hardens 
  

   rapidly. 
  Solution 
  of 
  gray 
  rubber 
  (b) 
  is 
  less 
  easy. 
  

  

  Solution 
  of 
  elastic 
  rubber 
  (a) 
  in 
  liquid 
  toluol 
  at 
  200° 
  also 
  

   takes 
  place 
  with 
  great 
  ease. 
  The 
  liquid 
  dries 
  slowly. 
  Pres- 
  

   sures 
  of 
  less 
  than 
  10 
  atm. 
  suffice. 
  

  

  11. 
  Solution 
  in 
  ethylic 
  and 
  higher 
  ethers. 
  — 
  Elastic 
  sheet 
  

   rubber 
  (a) 
  dissolves 
  at 
  once 
  in 
  liquid 
  ethylic 
  ether 
  at 
  200°. 
  

   Pressure 
  should 
  exceed 
  25 
  atm., 
  but 
  need 
  not 
  be 
  greater 
  than 
  

   40 
  or 
  50 
  atm. 
  The 
  solution 
  hardens 
  immediately 
  on 
  exposure 
  

   to 
  air. 
  Gray 
  rubber 
  (b) 
  is 
  attacked 
  with 
  difficulty. 
  

  

  12. 
  Treatment 
  with 
  alcohols. 
  — 
  At 
  200° 
  india 
  rubber 
  (a) 
  is 
  

   not 
  dissolved 
  in 
  liquid 
  methyl 
  or 
  in 
  liquid 
  ethyl 
  alcohol, 
  and 
  

   only 
  slightly 
  so 
  in 
  liquid 
  amyl 
  alcohol. 
  Thus, 
  again 
  the 
  solu- 
  

   bility 
  seems 
  to 
  increase 
  with 
  the 
  molecular 
  weight 
  of 
  the 
  sol- 
  

   vent. 
  § 
  18. 
  

  

  