Aru.  Jour.  Pliarm.  ) 
November,  1909.  } 
Book  Reviews. 
551 
proposes  that  instead  of  dissolving  the  alkaloid  in  an  excess  of 
sulphuric  acid  as  in  the  U.S. P.  methods,  an  excess  of  a  volatile 
acid  be  employed,  such  as  acetic  or  hydrochloric  acid  for  example, 
when  a  definite  amount  of  the  acid  would  become  fixed  by  combining 
with  the  alkaloid  and  could  in  most  cases  be  determined  with 
the  aid  of  phenolphthalein  as  indicator,  the  excess  of  acid  having 
been  volatilized.  If  hydrochloric  is  used  the  alkaloid  may  be  deter- 
mined indirectly  by  determining  the  chlorine  by  the  Volhard  method, 
which  may  have  a  wider  application  since  phenolphthalein  in  some 
cases,  as  for  example  morphine,  does  not  show  the  end  reaction 
very  sharply. 
Method  of  procedure:  about  0.2  Gm.  of  the  specimen  to  be 
examined  is  dissolved  in  an  excess  of  hydrochloric  acid  (about 
20  c.c  of  4  per  cent.),  the  liquid  completely  evaporated;  any  film 
which  may  have  formed  over  the  surface  is  broken  up  with  the 
aid  of  a  glass  rod  and  the  residue  allowed  to  remain  on  the  water- 
bath  ( 90-95  °C.)  for  three  hours.  It  is  then  taken  up  with  distilled 
water  (10-20  c.c),  phenolphthalein  solution  (3  drops)  added,  and 
titrated  with  standard  sodium  hydroxide  until  the  solution  develops 
a  light  pink  color.  At  this  point  one  more  drop  of  the  indicator 
is  added  and  if  the  solution  at  once  assumes  a  very  deep  pink  color, 
standard  acid  is  added  until  the  color  remaining  is  only  light  pink, 
the  alkali  equivalent  of  the  acid  thus  added  being  deducted  from 
the  total  alkali  added  first. 
Experiments  to  determine  the  effect  of  the  temperature  of  the 
water-bath  (90— 95 0  C.)  and  the  stability  and  of  varying  the  amount 
of  alkaloid  on  the  constancy  of  the  proportion  of  hydrochloric  acid 
in  the  alkaloidal  residue,  were  carried  out  on  the  alkaloids  quinine, 
quinidine,  cinchonine,  cinchonidine  and  strychnine.  It  is  shown  that 
fairly  close  results  may  be  obtained  whether  the  free  acid  is  titrated, 
using  phenolphthalein  as  indicator,  or  the  chlorine  determined  by 
Volhard's  method. 
In  the  case  of  quinine,  quinidine,  cinchonine  and  cinchonidine 
two  molecules  of  sodium  hydroxide  are  equivalent  to  one  mole- 
cule of  these  alkaloids.  This  is  not  in  entire  harmony  with  the 
view  that  both  quinine  and  strychnine  are  monacid  alkaloids  (see 
U.S. P.),  hence  results  might  be  obtained  from  a  study  of  the 
fixing  power  of  the  alkaloids  on  volatile  acids,  that  would  furnish 
conclusive  evidence  as  to  the  exact  relation  of  the  various  al- 
kaloids to  acids,  which  for  some  alkaloids  is  still  surrounded  by 
uncertainty.  John  R.  Rippetoe. 
