3Q 
Cinchona  Bark. 
/  Am.  Jour.  Pharm. 
I     January.  1902. 
leaves  a  clear  top  fluid,  which  can  be  decanted,  without  a  floating 
particle  going  with  it,  while  I  had  no  difficulty  neither  to  deprive 
the  marc  of  some  alkaloid  remaining. 
No  more  than  three  quantities  of  15  c.c.  aether  were  needed. 
After  this  washing,  no  alkaloid  could  be  detected,  when  the  residue 
was  transferred  to  a  funnel,  whose  stem  was  previously  plugged  up 
with  a  small  quantity  of  cotton.  Pressure  with  a  cork  and  evapor- 
ating of  the  aether  obtained  thereby  did  not  give  any  evidence  to 
Mayer's  reagent.  But  since  as  stated  satisfactory  quantitative 
results  were  obtained  by  substituting  petroleum-aether,  fractioned 
at  40°.,forethylic  aether,  Van  Ketel's  process  might  advantageously 
be  modified  in  this  direction ;  let  us  keep  this  in  mind. 
Cort.  cinchon.  succ.  in  No.  60  powder. 
Modified  "Prollius"  according  to  A  mixture  of  2  (two)  vol.  petrol,  ae. 
Xyons.  (B.  pt.  400)  and  1  (one)  vol.  chloro- 
form +  10  c.c.  ammonia  water  of 
0-96  s.g. 
Yield  5  per  cent.  tot.  alks.  Yield  5  per  cent.  tot.  alks. 
3  (three)  vol.  petrol,  ae.  to  1  (one) 
chloroform  yield  lower  results. 
Very  peculiar  and  unexpected  results  were  obtained  when  boiling 
with  "  aether  "  was  continued  longer  than  previous  experiments 
called  for.  The  6  5  per  cent,  bark  yielded  after  an  exposure  of  one 
hour  and  a  half,  3-38  per  cent. 
The  8-31  per  cent,  bark  yielded  already  after  half  an  hour  only 
6  1 5  per  cent.  Van  Ketel  offers  as  an  explanation  for  this  the 
theory  that  the  variable  proportions  of  cinchotannine  in  the  bark 
are  the  cause  of  it,  and  that  a  strong  base  as  lime  must  be 
present,  in  excess,  to  prevent  the  alkaloids  forming  in  aether  insoluble 
compounds  with  cinchotannine.  This  not-to-be  ignored  fact  will 
be  a  continually  recurring  source  of  errors  and  disappointments, 
and  a  very  unpleasing  feature  of  the  process,  I  am  bound  to  state. 
But  the  situation  has  to  be  accepted,  however  much  we  would  like 
to  make  chemistry  a  science  of  mathematical  accuracy. 
The  author  finally  offers  a  series  of  figures  to  prove  the  value  of 
a  true  representative  sample,  e.  g.t  that  the  whole  of  the  sample 
must  be  reduced  to  a  uniform  fineness  and  not  a  part  of  it  left 
unpowdered.   And  offers  evidence  that  careless  pulverizing  and  sift- 
