4i2  Glycyrrhizin  in  Licorice  Root.        \  Km^;^rm' 
alcohol.  The  liquid  is  allowed  to  stand  half  an  hour,  then  filtered, 
and  washed  with  80  per  cent,  (by  volume)  alcohol  until  colorless. 
Filtrate  and  washings  are  evaporated  to  a  syrup  to  remove  the  alco- 
hol. The  residue  is  transferred  to  a  flask  and  made  up  to  30  cc. 
with  water.  Three  cc.  of  dilute  sulphuric  acid  (10  cc.  of  H2S04  plus 
300  cc.  water)  are  added  slowly  with  stirring.  After  allowing  to 
stand  over  night  at  I2°-I5°,  the  liquid  is  decanted,  and  the  precipitate 
washed  four  times  with  ice  water,  and  dissolved  in  alcohol.  To 
neutralize  free  sulphuric  acid  2  drops,  of  ammonia  are  added,  and  the 
solution  evaporated  on  water  bath  to  constant  weight  in  a  tared  dish." 
The  method  of  Parry  gives  the  usual  picture  of  a  glycyrrhizin 
determination.  With  a  few  changes  this  method  has  been  adopted  by 
Evans'  Sons,  Lesher  &  AYebb,  and  by  Houseman.  The  gums  are  pre- 
cipitated with  much  alcohol,  etc.    The  proportion,  2.5  g.  of  licorice 
to  15  cc.  water,  is  in  my  opinion,  the  strongest  solution  which  can 
be  used  without  fear  of  loss.   The  addition  of  alcohol  to  give  a  mix- 
ture of  80  per  cent,  strength  is  presumably  the  strongest  alcoholic 
solution  which  may  be  used.    The  good  results  obtained  show  that, 
by  the  experimental  conditions  given,  losses  do  not  result.   The  alco- 
holic solution  after  evaporation  is  taken  up  to  30  cc.    In  my  opinion 
this  volume  is  correctly  chosen  according  to  experience.    The  re- 
quirement to  stand  overnight  at  I2°-I5°  C.  is  probably  not  always 
called  for.    The  supernatant  liquid  is  to  be  poured  off,  and  the  acid 
is  to  be  treated  by  washing  and  pouring  off  four  times  with  ice 
water.  I  only  succeeded  twice  in  getting  the  glycyrrhizic  acid  to  stick 
to  the  bottom  so  that  it  could  be  washed  without  loss.    In  such  a 
case  one  must  take  a  more  roundabout  way,  collecting  the  acid  on  the 
filter  and  then  dissolving  it  in  hot  alcohol.    By  this  treatment  losses 
are  not  excluded.  Unfortunately  Parry  gives  no  quantities  for  wash- 
ing with  ice  water,  but  it  is  highly  necessary  to  prescribe  exact  quan- 
tities. The  values  received  in  checking  the  method  are  good.    I  ob- 
tained from  2.5  g.  licorice,  0.230,  0.234,  0.239,  0.249,  0.249  g.  glycyr- 
rhizic acid,  i.  e.,  9.44-9.96  per  cent.   The  losses  on  5  g.  licorice  I  de- 
termined in  two  experiments  to  be  0.0284-0.0314  g.  glycyrrhizin, 
i.  e.,  1.1-1.3  per  cent.    I  found  about  49.5  per  cent,  insoluble 
matter.    In  summarizing,  I  would  state  that  the  Parry  method 
gives  usable  results,  although  a  purification  of  the  acid  is  not  at- 
tempted. 
