Am.  Jour.  Pharm. 
July,  1921. 
Studies  on  Licorice  Root. 
483 
cipitation  of  the  glycyrrhizin  by  sulphuric  acid.  A  little  alcohol  is 
rather  obstinately  held  by  the  syrup,  and  in  order  to  be  quite  safe  I 
prefer  to  remove  the  bulk^of  the  alcohol  by  distillation  in  a  round- 
bottomed  flask  from  a  steam  bath  without  vacuum,  and  finish  just  to 
dryness  under  a  vacuum.  Under  these  conditions  no  trouble  with 
bumping  need  be  experienced. 
Certain  other  criticisms  of  my  method  by  Linz  will  be  mentioned 
when  I  come  to  state  my  present  method  of  analysis. 
Linz  further  says :  "When  Houseman  states  in  conclusion  that 
he  weighs  pure  glycyrrhizin,  he  is  grossly  deceiving  himself."  Linz 
must  either  have  had  access  to  a  poor  abstract,  or  have  made  a  care- 
less translation  himself  at  this  point.  In  my  article  of  1912  I  am 
careful  to  state  that  crude  glycyrrhizin  is  weighed. 
Reference  must  here  be  made  to  the  method  of  Tschirch- 
Erikson,  because  of  the  prominence  of  the  first  author,  as  well  as 
on  account  of  the  originality  of  the  method  proposed.  Linz  has  very 
carefully  tested  Tschirch's  method,  which  seeks  to  determine  glycyr- 
rhizin, glucose  and  saccharose  successively,  on  the  basis  of  their  re- 
duction of  Fehling's  solution.  Linz  confirms  my  own  published  con- 
clusions that  the  method  proposed  by  Tschirch  for  determining 
glycyrrhizin  and  sugars  in  licorice  extract  and  in  root  is  completely 
unworkable. 
I  cannot  understand  how  Prof.  Tschirch  can  have  given  his 
sanction  to  the  publication  by  Erikson,  of  a  method,  upon  which 
obviously  not  nearly  enough  work  was  done,  and  which  also  on 
theoretical  grounds  is  quite  unsound. 
This  is  particularly  unfortunate,  because  the  name  of  Tschirch 
has  caused  some  acceptance  of  his  method  in  the  literature,  when  it 
would  otherwise  have  been  refuted.  I  find  the  Tschirch-Erikson 
method  given,  for  example,  in  a  new  book  by  Henry  C.  Fuller,  "The 
Chemistry  and  Analysis  of  Drugs  and  Medicines,"  1920,  page  50. 
My  own  method  is  given  in  a  later  chapter  in  the  book  (pp.  408- 
410). 
Having  disposed  of  the  methods  hitherto  proposed  for  the 
assay  of  licorice  extract  for  glycyrrhizin,  Linz  then  considers  the 
methods  for  licorice  root.  He  considers  only  two  methods  worth 
discussion — that  of  Tschirch-Erikson,  and  my  own.  He  is  forced 
to  refute  the  Tschirch-Erikson  method  for  the  same  reasons  as  apply 
to  licorice  extract,  and  accepts  my  method,  stating  that  it  gives  quan- 
titative yields  of  glycyrrhizic  acid,  with  a  high  degree  of  purity  of 
