Amjln7,'mhrm' }        Glycyrrhizin  in  Licorice  Root.  397 
ity  of  the  impure  acid.  But  here  one  encounters  manifold  difficul- 
ties in  its  accomplishment. 
Haffner,  Capin  and  Durier  were  each  working  with  different 
materials.  It  is  therefore  necessary  to  take  into  account  the  degree 
of  purity  or  impurity.  It  would  not  be  fair  to  judge  the  results  of 
an  experiment  on  one  acid  from  the  results  on  other  acids.  If  one 
wishes  to  obtain  exact  results  and  to  add  the  percentage  solubility  to 
the  value  found  in  a  glycyrrhizin  determination,  one  would  have  to 
do  a  solubility  determination  for  every  kind  of  glycyrrhizin  determin- 
tion.  In  that  case  it  would  be  necessary  to  dry  the  glycyrrhizin  at  a 
ioo°  to  constancy,  which  treatment  would  undoubtedly  change  its 
physical  properties.  I  would  only  quote  one  example — the  change  in 
its  solubility  in  alcohol,  if  one  dries  glycyrrhizic  acid  at  room  tem- 
perature. It  would  be  unreasonable  to  assume  that  the  washing  of 
the  precipitated  wet  acid  entails  the  same  losses  as  result  from  the 
use  of  the  completely  dried  acid.  In  spite  of  this,  it  has  been  pro- 
posed to  compare  these  results ! 
The  attempt  which  Capin  and  Durier  have  made,  to  correct  for 
the  losses  due  to  washing  in  the  respective  analytical  procedures,  by 
the  addition  of  a  number  to  the  glycyrrhizin  value  obtained,  which 
shall  be  valid  for  all  kinds  of  licorice  is,  in  both  cases,  not  only  inap- 
plicable on  account  of  inaccurate  experimental  conditions  which  re- 
sult from  the  solubility  determination,  but  is  also  open  to  fundamental 
objections.  The  values  which  both  have  found,  refer,  naturally,  only 
to  saturated  solutions,  which,  however  never  come  into  question  in  a 
glycyrrhizin  determination.  In  the  latter  case,  it  is  a  question  only 
of  washing  the  precipitated  acid  with  water,  and  of  the  solubility  of 
the  same  in  the  acidified  liquid  in  contact  with  it.  It  is,  therefore, 
quite  clear  that  totally  different  conditions  exist,  and  that  they  cannot 
be  compared  with  one  another.  The  experiment  of  Capin  and  Durier 
will  therefore  never  be  suitable  for  quantitative  work.  A  different 
method  which  I  will  mention  below  might  be  more  applicable. 
Summarizing,  I  would  therefore  state: 
1.  It  is  of  no  value  for  the  practical  glycyrrhizin  determination 
to  determine  the  solubility  of  the  pure  acid. 
2.  A  determination  of  the  solubility  of  the  impure  glycyrrhizic 
acid  cannot  be  carried  out  under  conditions  which  are  equivalent  or 
similar  to  those  of  a  glycyrrhizin  determination. 
