394  Glycyrrhizin  in  Licorice  Root.        { AmjJne^i.arm" 
As  a  third  extraction-liquid,  Haffner  proposes  a  mixture  of  sul- 
phuric acid  and  alcohol.  Alcohol  alone  dissolves  practically  nothing 
from  licorice  extract,  since  all  of  the  glycyrrhizin  compounds  are 
very  difficultly  soluble  or  almost  insoluble  in  alcohol.  By  the  addi- 
tion of  sulphuric  acid,  the  glycyrrhizin  compound  is  decomposed, 
and  the  free  glycyrrhizic  acid  is  formed,  which  is  easily  soluble  in 
the  mixture  of  alcohol  and  sulphuric  acid.  Haffner,  therefore, 
avoids  the  question  of  the  solubility  of  the  various  compounds,  by 
setting  free  the  glycyrrhizic  acid.  The  question  as  to  whether  this 
treatment  dissolves  out  all  of  the  glycyrrhizin,  I  can  answer  uncon- 
ditionally in  the  affirmative.  It  can  hardly  be  doubted  that  the  total 
glycyrrhizin  salts  of  licorice  are  decomposed  by  sulphuric  acid  or 
that  the  free  glycyrrhizic  acid  so  liberated  is  soluble  in  the  sulphuric 
acid-alcohol  mixture.  There  is  therefore  no  objection  to  Haffner's 
proposal  from  a.  quantitative  point  of  view. 
In  order  to  determine  whether  there  is  anything  soluble  in  am- 
monia in  the  dry  residue  from  Haffner's  method,  I  extracted  exactly 
5  grams  of  the  insoluble  matter  with  ammoniacal  water.  Even  after 
the  third  extract,  the  decanted  liquid  was  quite  black.  From  the 
united  evaporated  extracts,  I  was  able  to  obtain  0.189  grams  am- 
monium glycyrrhizinate  in  the  usual  analytical  way.  Since  this  5 
grams  residue  corresponds  to  about  10  grams  of  original  licorice  ex- 
tract, there  is  found  by  this  method,  in  the  residue  from  Haffner's 
method,  nearly  2  per  cent,  of  ''ammoniated  glycyrrhizin"  which  con- 
tains no  glycyrrhizic  acid,  but  which,  by  an  ammoniacal  extract  of 
licorice  would  probably  be  obtained  as  an  impurity  in  the  acid,  and 
would  be  weighed  as  glycyrrhizic  acid. 
I  would,  therefore,  state  my  opinion  on  the  various  proposed 
extraction-liquids  as  follows :  Both  the  aqueous  extract  followed  by 
alcohol,  and  also  the  alcohol-sulphuric  acid  extract,  give  good  re- 
sults; but,  on  the  contrary,  the  ammoniacal  extract  is  inferior  to 
both,  because  it  gives  values  which  are  higher  than  the  correct  figure. 
2.  The  Solubility  of  Glycyrrhizic  Acid. — As  far  as  I  could  de- 
termine, Haffner,  in  1899,  was  the  first  to  make  experiments  on  the 
solubility  of  glycyrrhizic  acid.  Maisch,  in  1884,  in  commenting  on 
the  method  proposed  by  Schroeder,  showed,  that  such  a  solubility 
determination  is  very  desirable.  Haffner  shook  up  glycyrrhizic  acid 
with  excess  of  water,  and  determined  the  solubility  by  evaporation. 
He  found  the  proportion  1  :  60,  which  corresponds  to  1.67  per  cent. 
