﻿360 
  0. 
  Barns 
  — 
  Solution 
  of 
  Vulcanized 
  India 
  Rubber. 
  

  

  over, 
  that 
  the 
  system 
  of 
  rubber 
  and 
  solvent 
  is 
  to 
  be 
  kept 
  under 
  

   pressure 
  sufficient 
  to 
  insure 
  the 
  liquid 
  state 
  of 
  the 
  solvent. 
  It 
  

   follows 
  obviously 
  that 
  this 
  temperature 
  must 
  only 
  be 
  so 
  high, 
  

   cset. 
  par., 
  as 
  to 
  change 
  in 
  the 
  least 
  degree 
  possible, 
  the 
  useful 
  

   character 
  of 
  the 
  rubber 
  eventually 
  to 
  be 
  deposited 
  from 
  solu- 
  

   tion. 
  Hence, 
  I 
  act 
  on 
  vulcanized 
  India 
  rubber 
  at 
  the 
  lowest 
  

   convenient 
  temperature 
  facilitating 
  the 
  solvent 
  action, 
  and 
  at 
  a 
  

   pressure 
  preferably 
  exceeding 
  the 
  vapor 
  tension 
  of 
  the 
  solvent 
  

   at 
  the 
  given 
  temperature. 
  Whatever 
  other 
  favorable 
  action 
  pres- 
  

   sure 
  may 
  exert 
  (such, 
  for 
  instance, 
  of 
  forcing 
  the 
  fluid 
  into 
  the 
  

   physical 
  pores 
  of 
  the 
  semi-solid 
  by 
  a 
  principle 
  akin 
  to 
  Henry's 
  

   law) 
  is 
  clear 
  gain. 
  In 
  my 
  machine* 
  it 
  is 
  rather 
  more 
  conven- 
  

   ient 
  to 
  act 
  under 
  100 
  atm., 
  or 
  more, 
  than 
  at 
  lower 
  pressures. 
  

   Hence 
  I 
  did 
  not 
  scruple 
  to 
  use 
  pressures 
  as 
  large 
  as, 
  or 
  above, 
  

   this, 
  testing 
  the 
  adequacy 
  of 
  low 
  pressures, 
  however, 
  by 
  special 
  

   experiment. 
  §§ 
  18, 
  20. 
  

  

  The 
  samples 
  of 
  vulcanized 
  rubber 
  acted 
  on 
  were 
  five 
  in 
  

   number, 
  and 
  their 
  character 
  may 
  be 
  detailed 
  as 
  follows 
  : 
  

  

  a. 
  Very 
  elasticf 
  sheet 
  rubber, 
  usually 
  not 
  pigmented, 
  trans- 
  

   lucent 
  in 
  thin 
  films, 
  brownish 
  in 
  color, 
  used 
  for 
  rubber 
  bands 
  and 
  

   sheeting, 
  chemical 
  rubber 
  tubing, 
  etc. 
  

  

  b. 
  Less 
  elastic 
  and 
  harder 
  rubber, 
  pigmented 
  gray, 
  opaque, 
  

   largely 
  used 
  for 
  rubber 
  tubing, 
  etc. 
  

  

  c. 
  Non-elastic, 
  pigmented 
  rubber, 
  flexible, 
  opaque 
  gray, 
  used 
  

   for 
  low 
  class 
  rubber 
  tubing 
  and 
  low 
  class 
  merchandise 
  in 
  general. 
  

  

  d. 
  Ebonite. 
  

  

  e. 
  Same 
  as 
  a, 
  rotted 
  by 
  age 
  and 
  exposure. 
  

  

  3. 
  Solution 
  in 
  carbon 
  disidphide. 
  — 
  From 
  experiments 
  made 
  

   at 
  100° 
  and 
  160°, 
  it 
  appears 
  that 
  elastic 
  sheet 
  rubber 
  (a), 
  is 
  not 
  

   fully 
  soluble 
  in 
  CS 
  2 
  in 
  a 
  reasonable 
  time, 
  if 
  at 
  all. 
  It 
  is 
  quite 
  

   soluble 
  at 
  185°, 
  and 
  soluble 
  to 
  a 
  remarkable 
  degree 
  and 
  at 
  a 
  

   remarkably 
  rapid 
  rate 
  at 
  210°. 
  Hence 
  the 
  pressure 
  under 
  

   which 
  solution 
  is 
  to 
  take 
  place, 
  should 
  here 
  be 
  greater 
  than 
  

  

  * 
  See 
  Proc. 
  Am. 
  Acad., 
  xxv. 
  p. 
  93, 
  1890, 
  or 
  Phil. 
  Mag-, 
  October, 
  1890. 
  p. 
  338. 
  

   The 
  present 
  method 
  of 
  work 
  is 
  simple: 
  Glass 
  tubes 
  L0 
  cm 
  to 
  15 
  cm 
  long, 
  and 
  -3 
  cm 
  

   or 
  -4 
  cm 
  in 
  diameter, 
  closed 
  at 
  one 
  end, 
  and 
  drawn 
  out 
  to 
  a 
  capillary 
  canal 
  with 
  

   three 
  enlargements 
  at 
  the 
  other, 
  were 
  filled 
  with 
  a 
  charge 
  of 
  vulcanized 
  rubber 
  

   and 
  solvent, 
  and 
  then 
  introduced 
  into 
  the 
  steel 
  piezometer 
  tube. 
  I 
  made 
  use 
  of 
  

   the 
  temperatures 
  of 
  boiling 
  turpentine 
  (160°). 
  aniline 
  (185°), 
  naphthalene 
  (210°), 
  

   and 
  diphenjdamine 
  (310°). 
  To 
  separate 
  the 
  charge 
  from 
  the 
  oil 
  of 
  the 
  piezometer 
  

   which 
  transmits 
  pressure, 
  I 
  first 
  employed 
  a 
  thread 
  of 
  mercury 
  inserted 
  into 
  the 
  

   capillary 
  canal. 
  Finding, 
  however. 
  § 
  17, 
  that 
  this 
  metal 
  acted 
  on 
  the 
  charge, 
  I 
  

   replaced 
  it 
  by 
  a 
  thread 
  of 
  water, 
  or 
  contiguous 
  threads 
  of 
  gasolene 
  and 
  water. 
  

   Charges 
  were 
  usually 
  introduced 
  in 
  the 
  ratio 
  of 
  one 
  part 
  by 
  volume 
  of 
  rubber 
  to 
  

   three 
  or 
  more 
  of 
  solvent, 
  § 
  18. 
  About 
  l 
  cc 
  to 
  2 
  CC 
  of 
  solution 
  were 
  obtained 
  per 
  

   heating. 
  I 
  made 
  considerably 
  over 
  150 
  experiments, 
  most 
  of 
  them 
  at 
  210° 
  and 
  

   100 
  or 
  200 
  atm. 
  Experiments 
  on 
  a 
  larger 
  scale 
  were 
  also 
  made 
  in 
  great 
  number, 
  

   chiefly 
  with 
  the 
  object 
  of 
  studying 
  the 
  product 
  deposited 
  from 
  solution. 
  § 
  20. 
  

  

  f 
  By 
  elastic 
  I 
  mean 
  extensible 
  with 
  resumption 
  of 
  the 
  original 
  shape 
  when 
  the 
  

   pull 
  ceases. 
  

  

  