Amjune,ri9^i.arm' }        Glycyrrhizin  in  Licorice  Root.  393 
are  present  in  the  extract,  I  will  here  only  consider  the  possibility 
that  it  can  be  a  question  of  a  potassium,  calcium,  magnesium,  and 
ammonium  salt.  The  potassium  and  ammonium  compounds  are 
very  easily  soluble  in  water.  The  literature  says  nothing  about  the 
magnesium  compound,  which  does  not  appear  to  have  been  pre- 
pared yet.  It  may,  however,  be  assumed  from  the  nature  of  mag- 
nesium salts,  that  the  glycyrrhizinate  is  easily  soluble.  As  regards 
the  calcium  salt,  Sestini  reports  that  it  is  difficultly  soluble  in  water. 
When  one  remembers,  however,  that  by  the  various  methods,  only 
very  trifling  quantities  of  calcium  salt  are  present  to  be  dissolved,  one 
may  assume  that  the  calcium  glycyrrhizinate  will  be  dissolved  in  the 
amount  of  water  used  in  the  determinations. 
All  possible  compounds  present  in  licorice  extract  as  "glycyr- 
rhizin" are  therefore  water-soluble  for  the  purposes  of  our  practical 
testing  comparisons.  A  free  acid  which  must  be  made  soluble  by 
alkali,  is  not  present.  It  is  therefore  superfluous  to  add  ammonia  to 
the  solvent.  Such  an  addition  is  not  only  unnecessary,  but  even  un- 
desirable, for  Haffner  has  proved  that  calcium  glycyrrhizinate  is  ex- 
tremely difficultly  soluble  in  ammonia.  There  is  another  important 
fact  which  argues  against  such  an  extraction.  It  is  proved  that  am- 
monia dissolves  a  considerable  quantity  from  the  residue  insoluble  in 
water.  If  it  be  possible  to  dissolve  out  with  water  the  total  glycyr- 
rhizic  acid  compounds  (and  I  am  of  the  opinion  that  this  can  be 
done,  provided,  of  course,  that  not  too  small  quantities  of  water  are 
used),  then  it  is  incorrect  to  use  ammonia,  and  thus  extract  still 
more  from  the  otherwise  insoluble  matter,  which  does  not  contain 
glycyrrhizin  compounds.  The  more  "non-glycyrrhizin"  the  filtered 
extract  contains,  the  more  impure  must  the  precipitated  glycyrrhizic 
acid  be.  Or,  positively  stated :  The  precipitated  glycyrrhizic  acid  is 
the  purer,  the  greater  the  insoluble  residue,  presuming,  of  course, 
that  the  total  glycyrrhizin  compounds  have  been  extracted  from  it. 
I  will  merely  mention  that  an  ammoniacal  licorice  extract  is  appre- 
ciably more  difficult  to  frlter  than  an  aqueous  extract.  The  above 
remarks  explain  why  I  obtain  higher  values  in  using  ammoniacal  ex- 
tracts, than  in  using  pure  water  in  the  control  experiments  to  be 
discussed  later.  This  excess  is,  however,  only  obtained  at  the  cost 
of  the  purity  of  the  weighed  product.  For  all  of  these  reasons  I 
hold  an  ammoniacal  treatment  of  the  original  licorice  extract  to  be 
incorrect. 
