£68  Soluble  Starch.  {A \*£i$g? 
SOLUBLE  STARCH. * 
By  M.  Musculus. 
Chemists  are  not  in  accord  as  to  what  is  to  be  understood  by  "  sol- 
uble starch."  Some  consider  as  such  the  matter  colored  blue  by 
iodine,  which  can  be  removed  from  starch  by  means  of  water,  and 
which  Naegeli  has  called  "granulose."  Others  think  that  the  sub- 
stance colored  violet  by  iodine,  which  Bechamp  obtained  by  treating 
starch  with  sulphuric  acid,  to  be  the  true  soluble  starch.  But  the 
author  has  found  that  granulose,  although  it  passes  readily  through  a 
filter,  is  not  really  soluble  in  water,  for  it  can  be  separated  by  evapo- 
ration in  a  state  completely  insoluble  even  in  boiling  water.  Also 
that  the  soluble  starch  of  Be'champ  is  a  mixture  in  which  may  be 
found  granulose,  soluble  starch,  and  the  products  of  decomposition  of 
starch  (dextrin,  glucose,  or  glucosin),  which  are  always  formed  with 
sulphuric  acid. 
The  author  has  previously  made  known  under  the  name  of  "  dextrine 
ghbulisee,,,f  a  body  insoluble  in  cold  water,  which  he  obtained  by 
dissolving  starch  in  boiling  acidulated  water,  and  evaporating  after 
saturation  of  the  acid  and  filtration,  to  the  consistence  of  a  syrup. 
This  deposits  an  abundance  of  granules,  insoluble  in  cold  water  and 
soluble  only  at  50°  C,  a  property  that  allows  of  their  being  washed 
and  separated  from  the  dextrin  and  glucose  by  which  they  are  accom- 
panied ;  further  treatment  with  alcohol  with  remove  a  little  granu- 
lose still  adhering,  and  there  will  then  be  left  what  the  author  con- 
siders to  be  true  soluble  starch  ;  the  granules  composing  it  being 
grains  of  starch  deprived  of  their  organization. 
The  author  enumerates  the  following  properties  of  this  product  to 
substantiate  his  assertion.  When  dried  in  the  air  it  is  white  and 
resembles  starch.  Freshly  washed,  it  is  insoluble  in  cold  water  and 
does  not  reduce  salts  of  copper  ;  but  if  it  be  left  for  some  time  in  con- 
tact with  water,  it  dissolves  perceptibly  and  there  is  at  the  same  time 
a  little  sugar  formed.  Its  rotatory  power  is  nearly  quadruple  that  of 
dehydrated  glucose.  It  dissolves  entirely  in  water  at  50°  C.,  and  is 
not  precipitated  upon  cooling ;  by  evaporation,  however,  a  residue  is 
obtained  which  has  recovered  its  insolubility  in  cold  water.   To  redis- 
f  Abstract  of  a  paper  read  before  the  French  Academy  (Comptes  Rendus, 
vol.  lxxviii,  p.  1413). 
*  Comptes  Rendus,  vol.  lxv,  p.  857. 
