ALKALOIDS  IN  THE  CINCHONA  BARKS. 
417 
ON  THE  EXAMINATION  OF  COMMERCIAL  SULPHATE  OF 
QUININE  FOR  OTHER  ALKALOIDS  FOUND  IN  THE  CINCHONA 
BARKS. 
By  Dr.  G.  Kerner. 
In  most  of  the  Pharmacopoeias  and  Chemical  Manuals  we 
find  the  well-known  ether-test  recommended  for  the  recognition 
of  cinchonine  and  quinidine,  in  commercial  sulphate  of  quinine. 
This  test  consists  in  treating  six  grains  of  the  sulphate  in 
question  with  from  sixty  to  seventy  drops  (=2  c.  c.)  of  ether  in 
a  well-stoppered  test  cylinder,  to  which  six  drops  of  liquor  am- 
monite are  added,  and  in  well  shaking  the  mixture.  The  fluid 
separates  into  two  layers,  a  clear  aqueous  and  an  ethereal  one. 
The  upper  layer  should  not  deposit  an  amorphous  or  crystal- 
line mass,  either  immediately  or  in  the  course  of  a  few  hours. 
This  method  suffices  in  most  cases,  for  it  indicates  even  minute 
traces  of  an  admixture  of  cinchonine  and  of  the  ordinary  quini- 
dine. It  indicates  clearly  one-half  to  three-quarters  per  cent. ; 
or  if  an  ether  which  has  been  previously  saturated  with  quini- 
dine be  employed,  even  smaller  quantities  of  the  latter  alkaloid. 
I  have,  however,  frequently  found  in  my  experiments,  that 
ether  cannot  implicitly  be  relied  on,  or  recommended  as  a  safe 
means  of  separating  the  bases  of  the  cinchona  barks.  The 
ether-test  itself  exhibits  irregularities  which  render  the  obser- 
vation of  the  reaction  a  matter  of  uncertainty.  The  ethereal 
solution  frequently  solidifies  to  a  gelatinous  mass,  which  at  times 
is  perfectly  clear  and  transparent,  sometimes  traversed  by*  net- 
like layers  of  enclosed  air,  which  impart  to  it  a  crystalline  ap- 
pearance, and  give  rise  to  errors,  since  they  render  it  exceed- 
ingly difficult  to  distinguish  whether  crystals  of  quinidine  have 
separated  from  the  ethereal  solution  or  not.  It  is  probable  that 
the  cause  of  the  formation  of  this  magma  will  be  explained  best 
by  viewing  it  as  a  double  salt  of  the  quinine  salt  with  the  am- 
monium salt  formed  in  the  reaction,  since  I  was  able  to  trace  in 
the  gelatinous  mass  almost  invariably  sulphuric  acid  and  a  salt 
of  ammonium,  not  met  with  in  the  ethereal  solution  when  the 
reaction  went  on  properly.  It  was  not,  however,  this,  for  the 
most  part  accidental  occurrence,  which  vitiated  the  ether-test, 
but  the  circumstance  which  my  experiments  brought  to  light, 
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