368 
Analysis  of  Barley. 
Am.  Jour.  Pharui. 
July,  1884. 
rated  to  dryness.  The  soluble  parts  of  the  residue  were  extracted 
with  sufficient  boiling  water  to  make  30  Cc.  When  tested  with 
Fehling's  solution  it  failed  to  reduce  it,  showing  that  no  reducing 
sugar  was  present,  also  that  the  acid  neutralized  by  sodium  hydrate 
was  capable  of  forming  a  reducing  sugar  by  acting  on  an  unreducable 
sugar  or  a  closely  allied  body. 
The  remaining  percolate  — 25  Cc. —  was  boiled  for  one  hour  with 
five  drops  of  hydrochloric  acid,  water  being  added,  from  time  to 
time,  to  preserve  this  measure;  it  was  then  neutralized  with  sodium 
carbonate  and  tested  with  Fehling's  solution  and  Sachsse's  test,  both 
were  reduced.  By  using  these  two  solutions,  we  can  estimate  the 
quantity  and  kind  of  a  number  of  reducing  sugars  and  bodies  form- 
ing reducing  sugars  by  being  boiled  with  acids.  For  instance,  cane- 
sugar  and  dextrin  belong  to  the  latter  class,  but  cane-sugar  forms 
invert-sugar  whilst  the  latter  forms  glucose,  and  these  two  products 
have  different  reducing  powers  with  Sachsse's  test,  but  the  same  with 
Fehling's  solution,  so  that  they  can  be  estimated  even  in  presence  of 
each  other.  Glucose,  maltose,  lactose,  etc.,  are  reducing  sugars  and 
therefore  are  not  present  in  the  above  extract.  To  establish  the 
identity  of  the  body  or  bodies  present  in  the  alcohol  extract,  a  solu- 
tion was  prepared  from  the  alcoholic  extract  of  20  Gm.  barley  exactly 
as  the  one  mentioned  before.  This  was  concentrated  to  40  Cc.  and 
tested  with  Sachsse's  test  and  Fehling's  solution. 
10  Cc.  Fehling's  solution  and  30  Cc.  water  were  brought  to  the 
boiling  point  in  a  porcelain  capsule,  and  the  above  solution  gradually 
added  until  all  the  cupric  oxide  was  reduced.  This  point  was  found 
by  occasionally  testing  for  copper,  by  taking  a  few  drops  from  the 
dish,  acidifying  with  acetic  acid  and  adding  a  few  drops  of  a  solution 
of  potassium  ferrocyanide.  As  long  as  there  is  copper  in  solution  a 
reddish  brown  precipitate  will  show  its  presence.  The  quantity  of  the 
solution  required  to  reduce  10  Cc.  Fehling's  solution  was  9*33  Cc. 
As  10  Cc.  of  Fehling's  solution  are  reduced  by  0*05  Gm.  sugar, 
9-33  :  0-05  ::  40  :  x  =  0*2144  Gm.  sugar  in  20  Gm.  barley. 
40  Cc.  Sachsse's  test  was  boiled  in  a  porcelain  capsule,  and  the  solu- 
tion gradually  added  until  all  of  the  mercuric  iodide — 0*72  Gm. — was 
reduced  to  metallic  mercury. 
This  point  was  found  by  occasionally  testing  a  few  drops  taken  from 
the  capsule  with  a  solution  of  potassium  hydrate  containing  stannous 
oxide.    If  mercury  is  still  in  the  solution,  a  black  precipitate  or  a 
