406  Glycyrrhizin  in  Licorice  Root.        { Amj£e,r'iS.arm" 
The  high  losses  are  caused  by  washing  the  precipitated  acid  with 
much  water,  and  by  the  solubility  of  the  acid  in  the  supernatant 
liquid.  I  obtained  29  to  30  per  cent,  insoluble  residue.  Helfen- 
berger's  method  does  not  attempt  a  purification  of  the  precipitated 
acid.  Since  alcohol  is  not  used  to  precipitate  gums  and  other  ma- 
terials, the  glycyrrhizic  acid  weighed  is  very  impure. 
Even  in  Helfenberger's  "Annalen"  of  19 13,  this  method  is  used. 
It  is  surprising  that  it  has  not  been  improved  in  the  course  of  years, 
since  in  latter  years  many  practical  proposals  have  been  published. 
3.  Capin  (191 1). 
"Two  g.  of  licorice  are  dissolved  in  20  cc.  distilled  water,  the 
filtrate  is  transferred  to  an  Erlenmeyer  flask,  2  cc.  sulphuric  acid 
(66  per  cent.)  are  added,  and  the  vessel  allowed  to  stand  on  ice 
with  frequent  shaking.  After  standing  24  hours,  the  liquid  is  poured 
on  a  smooth  filter  paper  and  the  residue  quickly  washed  by  decanta- 
tion  with  water  at  o°  to  remove  the  last  traces  of  sulphuric  acid.  The 
wash  waters  are  passed  through  a  second  smooth  filter,  and  the 
glycyrrhizic  acid  collected  on  this.  Through  the  second  filter  is  run 
10-15  cc.  distilled  water  containing  5  drops  of  ammonia  to  every  10 
cc,  and  the  liquid  is  received  into  the  Erlenmeyer  flask.  The  filter  is 
washed  with  water,  and  the  solution  evaporated  and  weighed  in  a 
tared  dish.  The  loss  from  2  g.  of  licorice  is  reckoned  as  0.11  and  is 
added  in." 
This  method  uses  the  experience  of  a  long  research  which  I 
treated  in  detail,  and  aims  to  be  an  improvement  of  the  method  of 
the  French  Pharmacopoeia.  Although  Capin's  method  may  be  re- 
garded as  an  improvement,  it  contains  a  number  of  serious  errors. 
Two  g.  licorice  are  to  be  dissolved  in  20  cc.  of  water,  and  the 
solution  filtered.  Capin  uses  no  alcohol.  This  filtration  requires  a 
long  time.  From  the  filtrate,  the  glycyrrhizin  is  to  be  precipitated 
by  sulphuric  acid.  Capin  does  not  speak  of  washing  the  filter,  al- 
though, of  course,  it  should  be  obvious.  If,  however,  one  would 
wash  until  almost  colorless,  one  would  obtain  a  volume  of  more  than 
50  cc.  from  which  to  precipitate  glycyrrhizic  acid  (in  one  case  I 
used  35  cc.  wash  water,  and  in  three  other  cases  none  at  all,  since 
the  method  does  not  call  for  it).  If  one  omits  the  washing,  losses 
result  from  the  material  staying  on  the  filter.  But  if  one  does  wash 
the  filter,  the  quantity  of  acid  precipitated  is  diminished  because  of 
