Amjifyri92?ann' }        Glycyrrhizin  in  Licorice  Root. 
463 
tents  of  the  dish  are  evaporated  to  25  cc.  on  the  water  bath.  After 
cooling,  transfer  to  a  tared  100  cc.  beaker  graduated  at  50  cc.  Wash 
out  the  dish  with  water  anci  bring  the  volume  exactly  to  50  cc.  Then 
add  5  cc.  of  water  which  contains  1.8  cc.  of  220  Be.  hydrochloric 
acid.  After  stirring  thoroughly,  allow  to  stand  12  hours,  so  that  the 
precipitate  sticks  on  the  bottom  of  the  beaker.  Pour  off  the  super- 
natant liquid  carefully,  and  wash  the  precipitate  and  beaker  with 
three  10  cc.  portions  of  water  at  2°  C.  Add  0.5  cc.  of  ammonia  (220 
Be.,  d  —  0.922)  and  dry  to  constant  weight  at  ioo°.  The  weight 
obtained,  multiplied  by  20,  gives  the  percentage  of  glycyrrhizin,  de- 
termined as  the  ammonium  salt." 
This  method  compares  advantageously  with  many  others  on 
account  of  its  exact  detailed  instructions.  The  amount  of  hydro- 
chloric acid  prescribed,  (I  prepared  it  exactly  22 0  Be.  corresponding 
to  a  34.4  per  cent.  HQ.,  and  having  a  Sp.  Gr.  of  1.171)  is  sufficient 
for  the  precipitation.  A  further  addition  of  acid  did  not  precipitate 
any  more  glycyrrhizin.  According  to  my  experience,  it  is  more 
desirable,  after  precipitating,  to  allow  to  stand  24  hours  instead  of 
12,  particularly  when  hydrochloric  acid  is  used.  Gadais  seeks  to 
achieve  a  purification  of  the  precipitated  acid,  by  decantation  with 
three  10  cc.  portions  of  water  at  2°.  I  do  not  believe  that  the 
total  hydrochloric  acid  is  washed  out  by  this  means.  Since  the 
ammonium  glycyrrhizinate,  after  drying,  shows  Beilstein's  chlorine 
reaction,  it  must  contain  ammonium  chloride  weighed  as  ammonium 
glycyrrhizinate.  The  wash  waters,  when  evaporated,  give  only  a  very 
slight  precipitate  with  sulphuric  acid,  which  is  to  be  ascribed  to  the 
slight  solubility  of  glycyrrhizic  acid  in  cold  water,  and  also  to  the 
fact  that  the  water  only  acts  on  the  surface  of  the  acid  for  a  short 
time.  From  5  g.  licorice  I  obtained  0.454,  0.459,  0.469,  0.476  g. 
which  corresponds  to  9^1-9.5  per  cent,  ammonium  glycyrrhizinate. 
As  the  loss,  I  figured  1.4- 1.6  per  cent.  The  insoluble  matter  was  44 
per  cent. 
This  method  is  well  worked  out,  being  especially  exhaustive  in 
the  instructions  given.  It  gives  practical  results,  except  for  the  un- 
avoidable errors  connected  with  every  glycyrrhizin  determination. 
14.  Gadais  II. 
"Ten  g.  licorice  extract  are  dissolved  in  100  cc.  water  in  a 
vessel  graduated  at  100  cc.  and  301  cc.  After  disintegration  of  the 
licorice  and  cooling,  water  is  added  up  to  the  100  cc.  mark;  170  cc. 
