﻿A 
  method 
  of 
  preparation 
  and 
  some 
  properties 
  of 
  a 
  starch 
  ge 
  

  

  Cornelia 
  Lee 
  Carey 
  

  

  Much 
  of 
  the 
  work 
  on 
  starch 
  has 
  been 
  on 
  saccharification 
  and 
  

   very 
  little 
  on 
  the 
  colloidal 
  properties, 
  particularly 
  those 
  of 
  the 
  

  

  I 
  

  

  starch 
  gel. 
  Although 
  starch 
  in 
  the 
  gel 
  condition 
  does 
  not 
  exist 
  

   in 
  nature, 
  it 
  is 
  interesting 
  both 
  from 
  a 
  colloidal 
  chemical 
  stand- 
  

   point 
  and 
  also 
  in 
  relation 
  to 
  carbohydrate 
  gels 
  such 
  as 
  agar 
  or 
  

   cellulose. 
  

  

  It 
  is 
  difficult 
  to 
  prepare 
  a 
  starch 
  gel 
  which 
  is 
  stiff 
  enough 
  to 
  be 
  

   handled 
  without 
  breaking 
  and 
  crumbling, 
  and 
  it 
  is 
  almost 
  impos- 
  

   sible 
  to 
  make 
  good 
  gels 
  of 
  very 
  high 
  concentration, 
  such 
  as 
  the 
  one 
  

   used 
  here, 
  by 
  the 
  usual 
  procedure. 
  It 
  was 
  with 
  this 
  idea 
  in 
  view 
  

  

  w 
  

  

  that 
  the 
  following 
  method 
  was 
  used. 
  A 
  loo 
  grams 
  of 
  commercial 
  

   corn 
  starch 
  were 
  well 
  mixed 
  with 
  150 
  ex. 
  of 
  cold 
  distilled 
  water, 
  

   and 
  the 
  mixture 
  then 
  poured 
  into 
  covered 
  petri 
  dishes. 
  Enough 
  

   starch 
  solution 
  was 
  poured 
  into 
  each 
  dish 
  so 
  that 
  the 
  bottom 
  was 
  

   just 
  covered. 
  A 
  number 
  of 
  these 
  dishes 
  were 
  then 
  put 
  in 
  the 
  

   autoclave 
  for 
  thirty 
  minutes 
  at 
  a 
  temperature 
  ranghig 
  from 
  105° 
  

  

  still 
  warm 
  the 
  starch 
  was 
  cut 
  into 
  strips. 
  

   They 
  were 
  then 
  put 
  over 
  the 
  radiator 
  to 
  dry, 
  later 
  in 
  the 
  oven 
  at 
  

   35° 
  C, 
  and 
  finally 
  dried 
  in 
  a 
  desiccator 
  over 
  calcium 
  chloride 
  to 
  

   constant 
  weight. 
  The 
  starch 
  prepared 
  in 
  this 
  manner 
  does 
  not 
  

   break 
  on 
  handline 
  and 
  when 
  placed 
  in 
  water, 
  at 
  low 
  temperatures, 
  

  

  to 
  110° 
  C. 
  When 
  

  

  WTien 
  completely 
  dry 
  it 
  Is 
  somewhat 
  

  

  ppears 
  

  

  IS 
  only 
  very 
  slightly 
  soluble, 
  

   transparent 
  and 
  tough, 
  Tht 
  

   standing 
  in 
  water 
  for 
  twenty 
  four 
  hours, 
  but 
  even 
  after 
  this 
  it 
  ir 
  

   still 
  fairly 
  tough. 
  Strips 
  of 
  this 
  starch 
  were 
  weighed, 
  put 
  in 
  100 
  

   c.c. 
  of 
  distilled 
  water 
  and 
  left 
  for 
  twenty-four 
  hours 
  at 
  different 
  

   temperatures. 
  Surface 
  water 
  was 
  removed 
  by 
  dipping 
  the 
  strips 
  

   quickly 
  into 
  alcohol 
  and 
  ether 
  and 
  blotting 
  on 
  filter 
  paper. 
  They 
  

   were 
  then 
  weighed 
  to 
  determine 
  the 
  amount 
  of 
  water 
  adsorbed. 
  

   In 
  all 
  cases 
  the 
  starch 
  kept 
  its 
  shape 
  and 
  at 
  low 
  temperatures 
  was 
  

  

  hard 
  and 
  firm. 
  

  

  The 
  water 
  in 
  which 
  the 
  starch 
  strips 
  had 
  been 
  standing 
  turned 
  

  

  455 
  

  

  