Amjui°y  ri92?arm' \        Glycyrrhizin  in  Licorice  Root.  457 
that  everything  soluble  might  certainly  be  extracted.  The  alcoholic 
extract  is  to  be  evaporated,  in  vacuum,  to  dryness.  Why  this  evapor- 
ation is  to  be  carried  so  far,  I  cannot  understand,  and  Houseman 
himself- does  not  further  offer  reasons  for  the  instruction.  It  suf- 
fices completely,  to  carry  the  evaporation  until  the  alcohol  is  driven 
off.  That  Houseman  has,  in  evaporating  to  dryness,  reckoned  with 
the  possibility  of  decomposition,  is  proved  by  his  care  in  evaporating 
in  vacuo.  I  carried  this  out  by  connecting  a  water  pump  to  the  arm 
of  a  distilling  flask  and  carefully  evaporating.  The  heating  took 
place  on  the  water  bath  at  as  low  a  temperature  as  possible.  Great 
care  is  necessary  here  on  account  of  possible  boiling  over.  In  my 
opinion,  this  whole  experimental  arrangement  is  superfluous,  since 
one  can  do  without  the  unnecessary  evaporation  to  dryness.  The  pre- 
cipitation of  glycyrrhizic  acid  takes  place  with  dilute  sulphuric,  of  the 
same  strength  used  by  Parry  and  Evans.  Houseman  allows  the  pre- 
cipitated acid  to  stand  only  two  hours,  on  the  ground  that  12  to  24 
hours  standing  is  superfluous,  and  gives  lower  results.  I  have  ob- 
served the  contrary  and  can  here  only  state,  that  sulphuric  acid,  after 
standing  longer  than  two  hours,  still  gives  a  brown  precipitate  which 
sticks  to  the  bottom  of  the  vessel,  and  which  is  soluble  in  ammonia. 
According  to  my  observations  which  I  have  made  on  a  large  number 
of  analyses,  standing  from  10  to  12  hours  is  recommended.  House- 
man also  makes  use  of  the  difficult  solubility  of  glycyrrhizic  acid 
in  ice  water,  but  avoids  the  false  experimental  conditions  of  Evans' 
Sons.  He  precipitates  at  io°,  and  then  places  the  vessel  on  ice.  The 
purification  of  .the  acid,  sticking  on  the  bottom  of  the  vessel,  takes 
place  by  decanting  four  times  with  ice  water.  Unfortunately,  House- 
man mentions  no  quantities.  I  have  already  often  stated  that  a  good 
purification  by  decantation  cannot  well  be  carried  out.  The  glycyr- 
rhizic acid  is  weighed  in  this  determination.  When  Houseman  states 
in  conclusion  that  he  weighs  pure  glycyrrhizin,  he  is  grossly  deceiving 
himself. 
-[Translator's  Note. — Houseman  makes  no  such  statement, 
but,  on  the  contrary,  expressly  states  that  he  weighs  crude  glycer- 
rhizin.   It  is  Linz  who  is  grossly  deceiving  himself .  (P.  A.  H.)] 
The  end  product  shows  exactly  the  same  color  as  all  the  other 
preparations  obtained  in  a  similar  way.  I  obtained  from  2  g.  licorice 
0.189,  0.193,  0.2  g.  glycyrrhizic  acid,  i.  e.,  9.45-10.0  per  cent.    I  de- 
