400  Glycyrrhizin  in  Licorice  Root.        |  Amjuner'i^arm* 
a  control  experiment  beforehand,  I  had  convinced  myself  that  the 
quantities  used  for  precipitation  were  sufficient.  After  standing  24 
hours,  and  filtering,  these  control  experiments  gave  no  further  pre- 
cipitate when  more  of  the  same  precipitant  was  added.    The  liquids 
were  filtered  after  standing  24  hours.  The  tartaric  acid  had  gelatin- 
ized the  contents  of  the  tube,  so  that  one  could  turn  it  upside  down 
without  anything  running  out.   Therefore,  it  cannot  be  used  for  pre- 
cipitating any  better  than  acetic  acid,  in  which  glycyrrhizic  acid  is 
easily  soluble.    The  colors  of  the  filtrates,  and  also  that  of  the  pre- 
cipitated acid,  show  great  variability.    The  filtrates  from  boric  and 
phosphoric  acid  precipitations  were  light  brown ;  those  from  sulphuric, 
hydrochloric  and  nitric  acid,  more  or  less  dark  brown  to  black.  The 
precipitated  acid  was  black  and  uninviting,  except  with  oxalic  acid, 
in  which  case  it  had  a  light  grey  color,  which  may  be  ascribed,  prob- 
ably, to  the  precipitated  calcium  salt.   To  each  of  the  clear  filtrates, 
I  then  added  2  cc.  dilute  sulphuric  acid.   After  standing  for  10  hours, 
it  was  found  that  all  of  the  solutions,  with  the  exception  of  the  sul- 
phuric and  hydrochloric,  had  precipitated  some  more  glycyrrhizin. 
The  amount  of  additional  precipitate  was  only  slight  in  the  case  of 
phosphoric  acid,  nitric  acid,  and  oxalic  acid,  but  was  considerable  in 
the  case  of  boric  and  formic  acids.    Reaction  between  the  first  pre- 
cipitant and  the  small  quantity  of  dilute  sulphuric  acid  need  not  be 
feared,  and  is  not  concerned  in  the  precipitation.    I  arrived  at  the 
same  conclusions  through  a  second  experiment.    I  prepared  a  puri- 
fied glycyrrhizic  acid  from  an  alcoholic  extraction  of  the  dried  acid, 
and  shook  up  with  water,  a  larger  quantity  than  could  be  dissolved. 
To  20  cc.  portions  of  the  clear  filtrate  in  large  test  tubes  I  added  2 
cc.  of  various  acids.    Sulphuric,  hydrochloric  and  phosphoric  acids 
gave  a  turbidity  immediately,  oxalic  and  nitric  acids  only  after  some 
time  and  finally  formic  acid  also  gave  a  trifling  turbidity.   The  liquid 
was  filtered  after  24  hours,  and  on  adding  2  cc.  sulphuric  acid  to  the 
still  more  dilute  glycyrrhizin  filtrate,  after  standing  10  hours  a  floc- 
culent  precipitate  was  formed  in  all  of  the  solutions,  with  the  excep- 
tion of  those  containing  hydrochloric  and  sulphuric  acids.  From 
these  two  simple  experiments  only  one  conclusion  is  possible:  Sul- 
phuric and  hydrochloric  acids  react  more  sharply  than  other  precipi- 
tants.    In  order  to  decide  which  of  these  two  acids  works  the  more 
strongly  I  proceeded  as  follows: 
A  saturated  solution  of  glycyrrhizic  acid  was  diluted,  in  one  case, 
