﻿Carey: 
  A 
  starch 
  gel 
  457 
  

  

  \ 
  

  

  T 
  

  

  partly 
  swelled, 
  at 
  the 
  temperature 
  at 
  which 
  the 
  gel 
  was 
  made, 
  due 
  

   to 
  lack 
  of 
  water. 
  It 
  will 
  be 
  remembered 
  that 
  the 
  gel 
  was 
  highly 
  

   concentrated, 
  66V3 
  per 
  cent, 
  and 
  it 
  may 
  be 
  that 
  swelling 
  goes 
  on 
  

   forming 
  a 
  paste 
  and 
  leaving 
  the 
  grains 
  only 
  slightly 
  changed, 
  due 
  

   to 
  the 
  insufficient 
  supply 
  of 
  water 
  present. 
  A 
  10 
  per 
  cent 
  gel 
  

   made 
  by 
  mixing 
  starch 
  and 
  cold 
  water 
  and 
  adding 
  boi 
  ing 
  water 
  to 
  

   it 
  contains 
  empty 
  sacs 
  in 
  the 
  gelatinous 
  mass. 
  A 
  2 
  per 
  cent 
  gel 
  

   after 
  boiling 
  five 
  minutes 
  showed 
  these 
  empty 
  envelopes. 
  These 
  

   are 
  probably 
  the 
  individual 
  covers 
  of 
  the 
  starch 
  grains. 
  Whether 
  

   further 
  disintegration 
  takes 
  place 
  in' 
  the 
  grains 
  of 
  the 
  gel 
  used 
  

   in 
  this 
  work 
  on 
  standing 
  in 
  water 
  at 
  higher 
  temperatures 
  is 
  not 
  

   known, 
  but 
  investigation 
  will 
  be 
  carried 
  on 
  along 
  this 
  phase 
  of 
  the 
  

   problem. 
  

  

  Meyer 
  (5), 
  in 
  his 
  work 
  on 
  starch, 
  observed 
  these 
  sacs. 
  The 
  

   early 
  stages 
  in 
  swelling 
  correspond 
  to 
  those 
  seen 
  in 
  the 
  gel 
  used 
  

   here. 
  In 
  this 
  formation, 
  according 
  to 
  him, 
  the 
  swelling 
  continues 
  

   until 
  the 
  sac 
  is 
  formed. 
  In 
  the 
  beginning 
  striations 
  appear 
  which 
  

   disappear 
  when 
  the 
  sacs 
  become 
  larger. 
  Later 
  the 
  walls 
  of 
  the 
  

   sacs 
  wrinkle 
  and 
  when 
  swelling 
  is 
  complete 
  the 
  walls 
  of 
  these 
  

   collapsed 
  sacs 
  consist 
  of 
  a 
  gel 
  which 
  is 
  made 
  of 
  amicroscopic 
  drops. 
  

   Meyer 
  also 
  worked 
  with 
  corn 
  starch. 
  He 
  prepared 
  it 
  by 
  first 
  

   mixing 
  the 
  starch 
  with 
  cold, 
  and 
  then 
  with 
  boiling, 
  water. 
  When 
  

   the 
  vessel 
  containing 
  the 
  starch 
  was 
  placed 
  in 
  boiling 
  water 
  for 
  

   five 
  minutes 
  all 
  the 
  grains 
  were 
  swollen 
  and 
  the 
  sacs 
  floated 
  freely 
  

   in 
  the 
  sol. 
  The 
  partly 
  swollen 
  grains, 
  observed 
  by 
  the 
  writer, 
  

   appeared 
  much 
  as 
  Meyer 
  has 
  described 
  them. 
  The 
  contents 
  were 
  

   striated, 
  the 
  stripes 
  running 
  out 
  from 
  the 
  center, 
  and 
  in 
  the 
  weaker 
  

   gels 
  the 
  sacs 
  seemed 
  empty. 
  

  

  The 
  gel 
  is 
  fairly 
  resistant 
  to 
  heat. 
  W^en 
  newly 
  made 
  and 
  while 
  

   still 
  hot, 
  if 
  boiled 
  in 
  water 
  for 
  fifteen 
  minutes, 
  only 
  a 
  small 
  part 
  went 
  

   into 
  solutioti. 
  If 
  the 
  gel 
  is 
  allowed 
  to 
  set 
  entirely, 
  the 
  amount 
  

   dissolving 
  becomes 
  less. 
  Gels 
  fully 
  dehydrated 
  when 
  boiled 
  fifteen 
  

   minutes 
  kept 
  their 
  shape. 
  They 
  dissolved 
  somewhat, 
  however, 
  

   as 
  the 
  liquid 
  gave 
  the 
  characteristic 
  blue 
  color 
  with 
  iodine. 
  If 
  a 
  

   10 
  per 
  cent 
  sol, 
  when 
  still 
  hot, 
  (i.e. 
  immediately 
  after 
  making) 
  

   •is 
  put 
  into 
  boiling 
  water, 
  it 
  dissolves. 
  When 
  the 
  same 
  gel 
  is 
  

   set 
  and 
  then 
  boiled 
  fifteen 
  minutes 
  only 
  part 
  of 
  it 
  goes 
  into 
  solution. 
  

   -It 
  would 
  appear 
  from 
  this 
  that 
  the 
  setting 
  of 
  the 
  sol 
  is 
  what 
  makes 
  

  

  