AmjJnerilnarm '}        Glycyrrhizin  in  Licorice  Root.  401 
with  twice,  and  in  another  case,  with  three  times  the  volume  of 
water,  and  to  10  cc.  portions  of  these  solutions  were  added  1  cc.  di- 
lute sulphuric,  and  1  cc.  dilute  hydrochloric  acid.  After  several 
hours,  all  four  test  tubes  showed  light  flocculent,  gelatinous  precipi- 
tates. From  another  saturated  solution,  in  order  to  avoid  possible 
decomposition,  I  made  a  dilution  in  the  proportion  of  1:2^2,  and 
added  to  each  10  cc,  1  cc.  of  the  acids.  This  time,  the  hydrochloric 
acid  solution  remained  quite  clear,  even  after  24  hours,  while  the 
sulphuric  acid  solution  gave  a  very  light,  but  positive  turbidity.  This 
proves  that  sulphuric  acid  unquestionably  precipitates  glycyrrhizic 
acid  quantitatively,  better  than  hydrochloric,  and  that  the  glycyr-  ¥ 
rhizin  is  more  difficultly  soluble  in  the  former  than  in  the  latter.  Sul- 
phuric acid  is  therefore  certainly  the  most  suitable  acid  for  precipi- 
tation. In  these  experiments,  I  have  intentionally  avoided  any  quan- 
titative determination,  since  it  is  here  a  question  of  only  very  small 
quantities  of  a  material  which  is  not  uniform.  Under  these  circum- 
stances, differences  in  the  third  decimal  place  can  hardly  have  any 
significance.  I  believe,  however,  that  for  practical  purposes  of  a 
glycyrrhizin  determination  my  two  experiments  are  sufficiently  con- 
vincing. From  them  may  be  stated  that  only  sulphuric  and  hydro- 
chloric acids  may  be  considered  as  precipitants,  and  that  the  first 
acid  works  more  exactly  and  sharply.  All  other  acids  cannot  be 
used. 
5.  Experiments  to  Establish  the  Purity  of  the  Acid  Weighed. — 
Since,  by  the  various  determinations,  acids  or  salts  of  various  degrees 
of  purity  are  weighed,  it  is  not  sufficient,  in  criticising  glycyrrhizin 
determinations,  to  compare  the  quantities  obtained  and  weighed.  Ac- 
count must  also  be  taken  of  the  purity  of  the  same.  The  only  at- 
tempt to  do  this  has  been  made  by  Haffner.  He  prepares  the  barium 
salt,  and  determines  the  barium  by  evaporation  with  sulphuric  acid, 
weighing  the  barium  sulphate,  and  has  in  this  manner  a  method  for 
determining  the  purity  of  the  glycyrrhizic  acid.  If  I  would  now  at- 
tempt, in  the  present  wor£,  to  determine  the  degree  of  purity  of  the 
acid,  I  could  not,  of  course,  at  once  accept  Haffner's  methods.  Haff- 
ner's  acetone  extracts  have  for  their  object  a  purification  of  the  acid 
which  is  quite  foreign  to  my  intention,  and  in  this  case  would  be 
quite  inaccurate.  I  tried  all  kinds  of  variations  of  Haffner's  pro- 
cedure without  attaining  my  object.  I  should  like,  first  of  all,  to 
mention  a  few  facts  established  in  this  connection.    A  filtered  solu- 
