484 
Studies  on  Licorice  Root. 
5  Am.  Jour.  Pharm. 
(      July,  1921. 
the  latter.  He  accepts  my  alcoholic  extraction  of  the  root  (this 
Journal,  December,  191 2,  p.  542)  as  a  considerable  improvement 
over  percolation  with  water. 
Before  summarizing  my  experience  of  the  last  few  years  in  the 
analysis  of  licorice  root  and  extract,  and  giving  what  I  consider  to  be 
the  best  method  available  at  this  time,  I  shall  examine  the  method 
which  Linz  himself  proposes  for  licorice  extract. 
The  Linz  Method  for  Determination  of  Glycyrrhizin  in  Licorice 
Extract. 
This  method  is  given  on  page  458  of  the  June  issue  of  this 
Journal.  There  are  no  fundamental  objections  tp  it,  but  it  is  open 
to  certain  minor  criticisms,  which  I  mention : 
1.  Linz  precipitates  starch  and  gums  with  alcohol  of  about  65 
per  cent,  strength,  and  washes  with  60  per  cent,  alcohol.  I  prefer 
to  use  75  per  cent,  alcohol  which  completely  dissolves  glycyrrhizin 
and  precipitates  gums  more  completely.  Unprecipitated  gums  will 
tend  to  make  the  glycyrrhizin  figure  too  high. 
2.  Linz  evaporates  the  alcoholic  solution  to  30  cc.  I  do  not  con- 
sider that  all  of  the  alcohol  is  sure  to  be  removed  from  the  remain- 
ing syrup.  A  trace  of  alcohol  will  make  the  subsequent  precipitation 
of  glycyrrhizin  with  sulphuric  acid  incomplete  and  yield  low  results. 
I  consider  the  alcoholic  solution  should  be  evaporated  almost  or  just 
to  dryness,  finishing  under  reduced  pressure  if  desired. 
3.  Linz  fails  to  specify  strength  of  sulphuric  acid  to  be  used  in 
precipitating  glycyrrhizin. 
4.  I  do  not  think  it  necessary  to  dry  the  glycyrrhizin  precipitate 
in  a  vacuum  desiccator  before  dissolving  it  in  95  per  cent,  alcohol. 
I  was  unable  to  dissolve  it  from  the  filter  paper  with  the  quantity  of 
alcohol  prescribed  by  Linz. 
5.  Linz  precipitates  a  second  portion  of  glycyrrhizin  from  the 
evaporated  filtrate  and  washings  from  the  first  (main)  portion.  This 
is  good,  but  the  second  portion  need  not  be  weighed  separately  from 
the  first  portion. 
I  pass  now  to  the  method  which  I  propose. 
DETERMINATION  OF  GLYCYRRHIZIN  IN  LICORICE  EXTRACT. 
For  this  determination  I  consider  that  a  centrifuge  is  practically 
indispensable. 
Two  grams  of  licorice  extract  in  a  100  cc.  centrifuge  tube  are 
