Am.  Jour.  Pharru.") 
February,  1896.  J 
The  Assay  of  Cinchona  Bark. 
33 
heavy  precipitates.  The  residue  was  now  treated  with  a  few  drops 
of  dilute  sulphuric  acid,  the  particles  disintegrated,  with  a  stirring 
rod,  as  much  as  possible,  and  washed  with  water  until  a  second  100 
c.c.  were  obtained.  The  filtrate  was  again  tested  as  above  with  the 
same  results.  The  above  operation  was  continued  until  500  c.c. 
were  obtained,  testing  the  filtrate  at  intervals  of  100  c.c.  After 
500  c.c.  had  passed,  the  filtrate  still  gave  a  turbidity  with  both  of 
the  above  reagents.  These  results  demonstrated  to  the  writer  that 
it  was  practically  impossible  to  obtain  all  of  the  alkaloids  by  the 
methods  embodying  the  above  procedure. 
Another  difficulty  inherent  in  these  methods  is  the  .proneness  of 
the  immiscible  solvents  to  emulsify,  and  the  slowness  of  separation. 
This  is,  undoubtedly,  due  to  the  mechanical  action  of  the  particles 
thrown  out  of  solution  on  rendering  the  latter  alkaline.  It  was 
necessary  to  discard  several  assays  in  this  work  on  account  of  this 
objectionable  feature. 
According  to  the  U.  S.  P.  process,  we  are  to  obtain  150  c.c.  of  the 
extracting  menstruum,  after  treating  the  bark  ;  but  the  writer's 
experience  has  been  that  only  about  140  c.c.  are  obtained.  The 
other  10  c  c.  are  only  obtainable  by  applying  pressure  to  the  bark 
on  the  funnel,  which  is  objectionable,  if  not  detrimental. 
The  method  of  Prollius  yields  impure  alkaloids  and  possesses 
several  undesirable  features. 
The  methods  that  have  proven  quite  satisfactory  are  those  in 
which  the  immiscible  extractive  solvents  are  directly  shaken  out 
with  acidulated  water.  Kiirsteiner's  modification  of  Haubensak's 
method  does  not  appear  to  possess  any  advantage  over  the  original 
process.  Keller's  modification  of  the  same  process  must  be  consid- 
ered of  secondary  importance,  although  very  good,  from  the  fact 
that  Mr.  Keller  has  published  a  second  and  better  method  for  the 
same  drug.  After  eliminating  the  above  processes,  we  have  left 
three  methods  that  leave  very  little  to  be  desired,  viz.:  Lyons' 
general  process  No.  2  with  Prollius'  mixture,  Haubensak's,  and  the 
chloroform-ether  processes.  With  the  bark  these  methods  varied 
from  one  another  only  0-2  per  cent.,  while  with  the  fluid  extracts 
there  was  even  less  variation.  The  color  of  the  alkaloids  of  these 
methods  is  also  very  good.  Those  obtained  by  Lyons'  and  Hauben- 
sak's methods  possess  a  slight  chocolate  color,  while  those  obtained 
by  the  chloroform-ether  process  are  more  nearly  white. 
