370 
Soluble  Starch. 
\  Am.  Jour.  Pharm. 
\     Aug.  1, 1874. 
When  starch  is  incompletely  dissolved,  either  with  diastase  or  boil- 
ing acetic  acid,  the  fragments  which  resist  the  longest  are  no  longer 
colored  blue  with  iodine,  but  take  a  tint  which  varies  from  yellow  to 
orange-red.  The  artificial  granules  give  the  same  colors  if  their  co- 
hesion be  augmented,  which  may  be  done  by  dissolving  in  water  and 
evaporating  to  dryness. 
Diastase  decomposes  soluble  starch  in  the  same  manner  as  natural 
starch,  but  much  more  easily  and  completely.  According  to  the  ob- 
servations of  Payen,  Schwarzer,  Schulze,  and  the  author,  when  dias- 
tase is  caused  to  act  upon  starch,  all  coloration  with  iodine  disappears 
when  the  degree  of  saccharification  reaches  one-fourth  ;  then,  by  aug- 
menting the  diastase,  the  saccharification  may  be  increased  to  one- 
half,  a  point  that  is  not  passed  to  any  sensible  extent ;  in  fact,  by 
his  earlier  experiments,  the  author  was  led  to  think  that  it  was  not 
possible  to  saccharify  more  than  one-third  of  a  given  quantity  of 
starch  by  means  of  diastase.  With  soluble  starch,  however,  the  stop- 
page of  the  saccharification  at  one-third  does  not  occur.  The  reac- 
tion with  iodine  disappears  when  it  reaches  one-fourth ;  then,  if  more 
diastase  be  added,  the  production  of  sugar  goes  on  rapidly  until  it 
reaches  one-half,  when  it  ceases,  as  with  natural  starch. 
A  widely  diffused  opinion,  introduced  into  science  by  Naegeli, 
regards  starch  as  essentially  composed  of  cellulose  mixed  with  a  little 
granulose.  Be'champ  has  found  that  dextrin  obtained  from  cellulose 
has  less  rotatory  power  than  dextrin  from  starch.  The  author  pre- 
pared dextrin  from  cellulose  by  dissolving  cotton  in  strong  sulphuric 
acid.  This  dextrin  was  afterwards  saccharified  with  boiling  acidulated 
water,  and  it  was  found  that  during  this  transformation  the  rotatory 
power  was  not  changed.  Starch,  treated  in  the  same  manner,  yielded, 
on  the  contrary,  a  dextrin  of  which  the  rotatory  power  had  been  low- 
ered more  than  one-half  by  the  saccharification.  It  follows  that  the 
dextrin  from  cellulose  has  the  same  rotatory  power  as  the  sugar 
which  is  derived  from  it,  which  is  not  the  case  with  that  from  starch. 
The  author  further  remarks  that  all  the  dextrins  of  starch  sugar  have 
a  rotatory  power  at  least  double  that  of  the  sugar  itself. 
It  is  known  that  glucose  freshly  dissolved,  and  especially  dehy- 
drated glucose,  has  a  rotatory  power  at  least  double  that  of  glucose 
that  has  been  some  time  dissolved  in  a  small  quantity  of  water ;  but 
this  property  is  not  persistent.  The  author  has  prepared  a  dextrin 
from  glucose,  by  treating  that  sugar  with  concentrated  sulphuric  acid 
