456  Glycyrrhizin  in  Licorice  Root.  \Am^y"m\&xm' 
10.  Houseman  (1912). 
"Two  g.  licorice  are  dissolved  in  10  cc.  hot  water  in  a  centrifuge 
tube.  After  cooling,  20  cc.  of  80  per  cent,  alcohol  are  added,  and 
then  gradually  50  cc.  of  95  per  cent,  alcohol.  The  tube  is  centrifuged 
after  standing  two  hours,  the  residue  is  stirred  up  twice  with  80  per 
cent,  alcohol,  and  again  centrifuged.  The  liquid  is  poured  off,  and 
evaporated  to  dryness  on  the  water  bath  in  vacuum.  The  residue  is 
transferred  with  30  cc.  water,  to  a  small  Erlenmeyer  flask,  and  the 
glycyrrhizin,  after  cooling  to  150,  is  precipitated  with  3  cc.  dilute 
sulphuric  acid  (10  cc.  H2S04  to  300  cc.  water).  After  standing 
two  hours,  the  contents  of  the  beaker  are  cooled  for  a  half  an  hour 
in  ice,  and  the  clear  liquid  poured  through  a  small  filter.  The  glycyr- 
rhizic  acid  is  washed  four  times  by  decantation  with  ice  water,  the 
precipitated  acid  remaining  in  the  flask,  as  well  as  any  which  has 
been  transferred  to  the  filter,  is  dissolved  in  dilute  alcohol.  Two 
drops  of  5  per  cent,  ammonia  are  added  to  neutralize  traces  of  sul- 
phuric acid,  and  the  solution  evaporated  to  constant  weight  in  a  tared 
dish." 
Houseman  has  modeled  his  method,  as  he  himself  states,  upon 
that  of  Parry. 
[Translator's  Note. — This  is  not  true.  Parry  obtained  the 
translator's  (Houseman)  method  confidentially,  and  published  it  as 
his  own  without  acknowledgment.  (P.  A.  H.)] 
The  new  feature  introduced  is  the  centrifuge.  The  method  has 
been  worked  out  exactly  by  the  author  and  gives  detailed  directions. 
He  does  not  confine  himself  alone  to  the  determination  of  glycyr- 
rhizin, but  also  gives  methods  for  determining  the  matters  insoluble 
in  cold  and  in  hot  water,  starch,  gums,  and  finally,  sugar  before  and 
after  inversion.  Gums,  etc.,  are  precipitated  by  a  large  volume  of 
alcohol.  According  to  my  view,  as  already  stated  in  discussing 
Parry's  method,  a  greater  concentration  of  alcohol  would  have  the 
danger  of  precipitating  glycyrrhizin  compounds.  In  order  that  any 
glycyrrhizin  which  is  precipitated  or  remains  undissolved,  shall  be  ob- 
tained in  the  determination,  Houseman  centrifuges  the  precipitate 
twice  more  with  80  per  cent,  alcohol.  The  amount  of  alcohol  used 
is,  unfortunately,  not  stated.  It  would  presumably  answer  the  pur- 
pose, to  warm  the  mixture  somewhat  before  centrifuging,  in  order 
