Kernels  Quinine  Test.  137 
In  general  I  have  operated  at  a  temperature  of  60°  C,  which  cor- 
responds sufficiently  well  to  the  too  vague  expression  in  the  Codex  ; 
but  in  principle  I  see  no  inconvenience  in  adopting  any  higher  tem- 
perature, even  that  of  boiling  water,  which  has  the  advantage  of  be- 
ing easily  applied  and  kept  constant.  I  even  propose  to  show  that 
the  boiling  temperature  should  be  adopted,  and  also  that  the  other  con- 
ditions of  the  test  should  be  rendered  more  stringent  if  it  be  desired 
to  require  the  complete  purity  of  the  official  quinine  sulphate,  while, 
on  the  contrary,  if  it  be  admissible  to  tolerate  in  that  salt  a  small  pro- 
portion of  foreign  alkaloids,  the  tolerance  will  be  so  much  the  less  in 
proportion  as  the  temperature  is  higher.  The  misconception  of  these 
conditions  lies  at  the  root  of  most  of  the  discussions  raised  on  the  sub- 
ject, and  of  the  objections  urged  against  the  method  of  assaying  in 
question. 
If  evidence  of  the  purity  of  the  salt  is  to  be  obtained,  it  is  clear 
that  in  order  to  test  it  the  whole  of  the  foreign  salts  that  are  to  be  de- 
tected must  be  made  to  pass  into  solution.  It  is  therefore  necessary 
to  dissolve  as  much  as  possible  of  the  crystals,  or,  in  other  words,  to 
raise  the  temperature  as  much  as  possible.  It  has  been  contended 
that  if  the  solution  is  made  with  heat  above  the  temperature  of  35°  C, 
even  pure  quinine  sulphate  will  not  answer  the  requirements  of  the 
Codex  test,  the  reason  being  that  the  hot  solution  remains  super- 
saturated after  being  cooled  to  15°  C.  But  it  is  easy  to  prove  that 
the  experiments  upon  which  that  statement  has  been  based  were  made 
with  very  impure  quinine  sulphate.  Moreover,  the  suggested  explan- 
ation is  no  more  admissible  than  the  statement  of  the  alleged  fact,  for 
a  saline  solution  cooled,  as  in  this  case,  in  contact  with  a  large  quanti- 
ty of  crystals  of  the  salt  in  solution,  would  not  remain  supersaturated. 
When,  in  short,  the  Codex  text  is  applied  to  really  pure  quinine 
sulphate  by  heating  on  a  water-bath  to  100°  C.  in  making  the  solution, 
the  liquid  obtained  will  remain  limpid  after  the  addition  of  ammonia 
just  as  well  as  when  the  temperature  has  been  raised  only  to  a  much 
lower  degree.  But  that  is  not  all,  and  when  in  that  case,  operating 
either  with  or  without  heat,  the  ammonia  (0'96  specific  gravity)  is 
gradually  added  to  the  5  cc.  of  the  properly  cooled  solution,  it  will  be 
found  that  in  order  to  dissolve  the  precipitate  at  first  formed  it  is  not 
requisite  to  use  the  7  cc.  of  the  reagent  ordered  by  the  Codex,  but 
that  a  much  less  quantity,  about  5*5  cc,  will  be  found  sufficient  for 
restoring  the  clearness  of  the  liquid. 
Am.  Jour.  Pharm. 
March,  1887. 
