478 
Glycyrrhizin  in  Licorice  Root. 
5  Am.  Jour.  Pharm. 
(      July,  1921. 
tion  is  highly  sensitive  to  small  changes  in  temperature,  she  does  not 
specify  or  control  such  temperature  accurately.  Linz's  proof  already 
given  for  extract,  that  Erikson's  method  cannot  be  possibly  used, 
applies  also  in  the  case  of  root  and  further  detailed  criticism  is  super- 
fluous.   (P.  A.  H.)] 
I  summarize  my  criticism  as  follows :  The  Tschirch-Erikson 
method  for  glucose  determination,  has  the  same  drawbacks  when 
applied  to  root,  as  when  applied  to  extract.  The  method  does  not 
consider  the  secondary  reactions  which  take  place  with  the  use  of 
Fehling  solution.  The  method  for  determining  the  time  the  Fehling 
solution  is  to  act,  is  open  to  objection.  The  instructions  for  the 
method  are  inexact,  and  take  no  account  of  the  results  of  her  own 
experiments.  There  is  no  doubt  that  the  total  glucose  is  not  deter- 
mined by  Erikson's  method. 
3.  Determination  of  Saccharose. 
[Translator's  Note. — Linz  shows  that  saccharose  does  not  re- 
duce Fehling  solution  at  all,  by  three  minutes  boiling,  and  that  the 
method  is  hopeless.  (P.  A.  H.)] 
4.  Determination  of  Glycyrrhizic  Acid. 
[Translator's  Note. — Linz  objects  to  the  absence  of  exactly 
specified  quantities  of  reagents  and  shows  that  a  maximum  precipi- 
tation of  cuprous  oxide  in  14  hours,  simply  represents  a  condition  of 
equilibrium,  at  which  no  further  self-reduction  of  Fehling  solution 
takes  place. 
He  is  right  in  passing  the  same  unfavorable  judgment  on  this 
method  for  root  as  he  did  in  the  case  of  extract.    (P.  A.  H.)] 
2.   HOUSEMAN  (1913). 
That  which  makes  the  glycyrrhizin  determination  more  diffi- 
cult in  root  than  in  licorice  extract,  is  the  act  of  dissolving  out  the 
glycyrrhizic  acid,  quantitatively.  Erikson  attempts  to  exhaust  the 
root  by  percolation.  There  are  objections  to  this  method,  even  of  a 
purely  practical  kind.  The  starch  in  the  root  swells  up  so  much, 
and  sometimes  gives  such  a  thick  mess  that  no  water  percolates 
through. 
Houseman  has  used  another  method.  He  first  of  all  exhausts 
the  root  with  95  per  cent,  alcohol,  and  claims  that  there  is  no  glycyr- 
