Am  Jour.  Pharm. 
July, 1884. 
Analysis  of  Barley. 
369 
brownish  coloration  is  produced.  It  required  20  Cc.  of  the  solution 
to  reduce  40  Cc.  of  the  test,  therefore  the  solution  was  capable  of 
reducing  80  Cc,  or  1*44  Gm.  mercuric  iodide.  It  requires  0*1501 
Gm.  glucose,  represented  by  x,  to  reduce  0*72  Gm.  Hgl2,  whilst  of 
invert-sugar,  represented  by  y,  only  0*1072  Gm.  is  required.  From 
these  figures,  the  relative  value  of  x  is  obtained  as  4*79,  and  that  of  y 
as  6-71. 
The  amount  of  sugar  estimated  by  Fehling's  solution,  and  the 
amount  of  mercuric  iodide  reduced  by  the  same  quantity  of  the  solu- 
tion, give  the  data  for  estimating  the  amount  of  sugar  or  of  sugar  and 
dextrin  present.  First,  the  equations  x  -j-  y  =  0*2144  and  479  x  -j- 
671?/  =  1*44  are  formed.  By  calculation  it  is  found  that  y  =  0*2144 
and  x  =  0,  showing  that  invert  sugar  only  is  present.  But  this  sugar 
was  not  present  in  the  original  extract,  as  that  did  not  reduce  the  test 
solutions,  so  it  must  have  been  produced  from  cane  sugar,  by  boiling 
with  hydrochloric  acid,  or  by  the  body  which  has  an  acid  reaction. 
1  mol.  cane  sugar — C12'H220ll,  342 — on  boiling  with  acids  is  changed 
to  form  2  mol  .*in  vert-sugar — C6H1206, 180 — by  combining  withH20. 
According  to  this,  the  0*2144  Gm.  invert-sugar  is  produced  frm  0*204 
Gm.  cane-sugar,  or  1*02  per  cent. 
Cold  Water  Extract. — The  barley  not  dissolved  by  the  alcohol  was 
dried,  and  weighed  7*83  Gm.  This  was  macerated,  and  percolated 
with  cold  water  until  exhausted.  The  percolate  was  concentrated  to 
40  Cc.  and  tested  with  Feh ling's  solution,  which  it  failed  to  reduce. 
After  boiling  it  for  two  hours  with  a  liltle  dilute  sulphuric  acid,  neu- 
tralizing with  sodium  carbonate,  and  again  testing,  it  reduced  the  test 
solution,  showing  the  presence  of  0*206  Gm.  sugar.  The  whole 
extract  was  capable  of  reducing  0*987  Gm.  Hgl2,  x  -f-  y  =  0*206  and 
4*79  x  +  6*71  y  =  0*987,  showing  that  the  sugar  formed  by  boiling 
with  the  acid  consisted  wholly  of  glucose,  and  this  was  produced  from 
dextrin.  Dextrin — C6H10O5,  162 — when  boiled  with  dilute  acids,  com- 
bines with  H20  to  form  1  mol.  glucose — C6H1206,  180 — so  that  the 
amount  of  glucose  was  formed  from  0*185  Gm.  of  dextrin. 
The  remainder  of  the  barley  when  dried  weighed  7*438  Gm.,  and 
the  extracted  matter  by  water,  amounting  to  0*392  Gm.,  consisted  of 
dextrin,  proteids  and  ash. 
Acid  Extract. — The  portion  not  dissolved  by  the  previous  treatment 
was  mixed  with  200  Cc.  water  and  5  Cc.  sulphuric  acid,  and  boiled 
for  eight  hours,  water  to  preserve  this  quantity  being  added  occasion- 
24 
