412 
ON  GLUCOSE. 
malt.  For  this  purpose  10  to  12  pounds  of  barley  malt  are  well 
stirred  with  400  pounds  of  water,  and  to  this  are  added  100 
pounds  of  starch,  and  the  whole  is  heated  to  158°  F.,  and  kept 
at  that  temperature  for  several  hours,  under  constant  agitation. 
At  158°  F.  the  starch  becomes  pasty,  the  grains  burst,  and  at 
first  there  are  no  signs  of  sugar,  but  in  a  quarter  of  an  hour  the 
liquid  becomes  more  fluid  and  begins  to  have  a  sweetish  taste. 
Great  care  must  be  observed  to  retain  the  heat  at  the  same  tem- 
perature, not  to  hiive  it  either  higher  or  lower  than  above  indi- 
cated, and  to  insure  this  several  thermometers  ought  to  be  put 
in  different  parts  of  the  apparatus.  After  six  hours  the  liquor 
can  be  filtered  and  clarified,  and  evaporated  to  a  syrup.  The 
sugar  prepared  in  this  way  always  retains  the  taste  of  malt  and 
is  only  adapted  to  use  in  breweries,  where  this  property  will  not 
prove  deleterious. 
Grape  sugar,  or  glucose,  can  be  prepared  in  open  vessels  by 
allowing  a  mixture  of  starch  and  water  to  flow  gradually  at  a 
temperature  of  130°  F.  into  a  vat  containing  water  acidulated 
with  one  per  cent,  of  sulphuric  acid.  By  keeping  it  at  a  boiling 
point  the  starch  is  at  once  altered,  without  producing  mucilage. 
The  amount  of  starch  taken  is  usually  about  one-half  the  weight 
of  water  employed.  After  all  of  the  starch  is  added,  boil  for 
half  an  hour  and  decant.  The  sulphuric  acid  is  neutralized  by 
carbonate  of  lime  as  before  and  the  liquid  evaporated  to  the 
specific  gravity  of  1*28,  and  set  aside  to  crystallize.  The  mo- 
lasses is  allowed  to  drain  off,  and  the  sugar  is  dried  at  a  gentle 
heat  in  a  current  of  dry  air. 
In  the  United  States,  especially  in  the  West,  it  is  more  eco- 
nomical to  make  grape  sugar  from  corn.  There  are  several 
large  establishments  where  this  business  is  now  extensively 
prosecuted.  The  corn  is  steeped  in  weak  soda  lye  to  separate 
the  husk  and  soften  the  gluten.  It  is  then  ground  wet  and  run 
through  revolving  sieves,  by  which  the  husks  and  gluten  are 
separated.  The  starch  flows  through  long  ways  and  troughs,  in 
which  are  slats  against  which  the  solid  particles  lodge,  and  thus 
separate  from  the  water.  The  wash  water  is  run  into  a  large 
cistern,  where  it  can  be  fermented  into  weak  vinegar.  The  starch 
is  put  wet  into  a  mash  tub  and  treated  with  one  per  cent,  sul- 
phuric acid  in  sufficient  water  for  three  to  eight  hours.  Where 
