Amjuner I92iarm'  \        Glycyrrhizin  in  Licorice  Root.  391 
such  a  determination,  gives  to  the  Foundation:  Research  of  this  yea»r 
great  practical  value. 
Various  workers  in  this  province  have  designated  as  "thank- 
less," their  activities  with  glycyrrhizin,  not  only  in  the  matter  of  ulti- 
mate analysis,  but  also  from  a  quantitative-analytical  point  of  view. 
This  is  easily  understood,  particularly  in  the  latter  respect.  A  pure 
glycyrrhizin,  or  an  equivalent  compound,  can,  in  my  opinion,  not  yet 
be  obtained  quantitatively.  One  only  obtains  a  more  or  less  impure 
acid  or-  derivative,  with  varying  losses. 
INTRODUCTION  TO  QUANTITATIVE  DETERMINATIONS. 
Before  I  enter  into  control  experiments  of  the  individual  meth- 
ods proposed,  and  the  results  obtained,  I  should  like  to  discuss  here 
some  fundamental  questions  which  are  of  common  importance  to  all 
or  many  of  the  methods  proposed.  I  think  I  can,  by  this  means, 
avoid  unnnecessary  repetition. 
In  the  first  place  may  be  mentioned  the  influence  of  the  liquid 
which  is  used  as  a  solvent  for  the  licorice  extract.  Further,  account 
should  be  taken  of  the  acid  used  for  precipitation.  Then,  the  solu- 
bility of  the  glycyrrhizic  acid  in  the  precipitant,  and  in  water,  and 
the  resultant  losses  must  be  investigated.  And,  finally,  account  must 
be  taken  of  the  degree  of  purity  of  the  substance  weighed.  As  re- 
gards the  many  questions  which  apply  only  to  individual  determina- 
tions, I  shall  consider  these  under  the  respective  methods. 
1.  The  Liqtmd  Used  to  Dissolve  the  Licorice  Extract. — The  first 
proposals  are,  naturally,  to  dissolve  the  licorice  in  water,  but  it  was 
found  that  this  solution  is  extremely  difficult  to  filter.  In  order  to 
avoid  this  trouble,  Diehl  proposed,  in  1883,  to  add  an  equal  volume 
of  alcohol  after  dissolving  in  water,  and  then  to  filter  after  settling. 
It  is  interesting  that  Diehl  emphasized  this  proposal,  on  the  ground 
of  the  easier  filtration  achieved.  However,  he  not  only  achieved  this 
practical  object,  but  also  obtained  a  greater  purity  in  the  acid  which 
is  separated  later.  By  the  addition  of  alcohol,  the  gummy  and  muci- 
laginous substances,  which  are  present  in  considerable  quantity,  and 
which  would  otherwise  pass  into  the  filtrate,  are  precipitated.  In 
the  subsequent  precipitation,  one  also  naturally  obtains  a  purer 
glycyrrhizic  acid.  In  any  case,  the  addition  of  alcohol  to  the  aqueous 
extract  must  be  regarded  as  an  improvement,  especially  since  no  loss 
