﻿456 
  

  

  Carey: 
  A 
  starch 
  gel 
  

  

  blue 
  with 
  iodine, 
  but 
  the 
  amount 
  of 
  starch 
  dissolved 
  at 
  low 
  tem- 
  

   peratures 
  was 
  not 
  large. 
  This 
  increases 
  as 
  the 
  temperature 
  

  

  rises. 
  

  

  GO 
  

  

  allowed 
  to 
  stand 
  for 
  twenty-four 
  hours. 
  An 
  aliquot 
  portion 
  of 
  

   the 
  liquid 
  was 
  taken, 
  evaporated 
  and 
  dried 
  to 
  constant 
  weight 
  in 
  a 
  

   desiccator. 
  Table 
  I 
  gives 
  the 
  results, 
  taken 
  from 
  only 
  one 
  deter- 
  

  

  TABLE 
  r 
  

  

  Temperature 
  degrees 
  Centigrade 
  

  

  Dry 
  weight 
  of 
  strip 
  in 
  grams 
  

  

  Volume 
  of 
  water 
  remaining 
  after 
  adsorption, 
  cc. 
  . 
  

   Starch 
  residue 
  in 
  25 
  cc. 
  of 
  above 
  water, 
  in 
  grams 
  

  

  Total 
  weight 
  of 
  starch 
  residue, 
  in 
  grams 
  

  

  Per 
  cent 
  weight 
  of 
  original 
  strip 
  dissolved 
  , 
  

  

  2.064 
  

   97.768 
  

  

  o.ooi 
  

  

  C.039 
  

  

  0.19 
  

  

  0.800 
  

  

  97-432 
  

   0.006 
  

   0.024 
  

   2.90 
  

  

  mination 
  in 
  each 
  case. 
  In 
  plotting 
  the 
  graph 
  as 
  indicated 
  by 
  the 
  

  

  very 
  

  

  amount 
  of 
  the 
  gel 
  which 
  passes 
  Into 
  solution 
  at 
  70° 
  C. 
  At 
  the 
  

   lower 
  temperatures 
  the 
  correction 
  would 
  be 
  negligible 
  as 
  is 
  shown 
  

   in 
  Table 
  II. 
  The 
  correction 
  has 
  been 
  applied 
  tentatively 
  for 
  the 
  

  

  more 
  

  

  mination 
  to 
  determine 
  it 
  definitively. 
  In 
  any 
  event 
  it 
  is 
  obvious 
  

   that 
  the 
  adsorption 
  of 
  water 
  per 
  gram 
  starch 
  gel 
  would 
  actually 
  

   be.even 
  greater 
  than 
  as 
  given 
  in 
  the 
  tables 
  at 
  the 
  end 
  of 
  this 
  paper. 
  

   It 
  seems 
  possible 
  that 
  the 
  substance 
  dissolved 
  in 
  the 
  water 
  does 
  

   not 
  do 
  so 
  immediately, 
  but 
  only 
  on 
  standing. 
  No 
  work, 
  however, 
  

   was 
  done 
  to 
  determine 
  this. 
  The 
  liquid 
  at 
  90° 
  C. 
  and 
  also 
  those 
  at 
  

   lower 
  temperatures 
  gave 
  no 
  test 
  for 
  reducing 
  sugars 
  with 
  Fehling's 
  

   solution. 
  At 
  the 
  higher 
  temperatures 
  the 
  strips 
  became 
  larger 
  and 
  

   softer 
  than 
  at 
  the 
  lower 
  but 
  kept 
  their 
  shape. 
  

  

  A 
  microscopical 
  view 
  of 
  a 
  section 
  of 
  one 
  of 
  these 
  starch 
  strips 
  

   showed 
  that 
  it 
  did 
  not 
  have 
  a 
  homogeneous 
  structure 
  but 
  was 
  

   made 
  of 
  partially 
  decomposed 
  starch 
  grains 
  with 
  a 
  jelly-like 
  

   substance 
  betw^een 
  them 
  which 
  cements 
  or 
  holds 
  them 
  together. 
  

   These 
  partly 
  swollen 
  grains 
  appeared 
  unchanged 
  even 
  after 
  

   boiling 
  ten 
  minutes 
  in 
  water. 
  There 
  may 
  have 
  been 
  a 
  slight 
  

   increase 
  in 
  size, 
  but 
  no 
  measurements 
  were 
  taken 
  to 
  determine 
  

   this. 
  It 
  is 
  the 
  opinion 
  of 
  the 
  writer 
  that 
  the 
  starch 
  grains 
  only 
  

  

  