Am.  Jour.  Pharm.  \ 
August,  1887.  / 
Quinine  Testing. 
411 
dissolve  5  grams  of  the  sulphate  in  question  in  150  c.c.  of  boiling 
water,  and  after  the  cooled  solution  has  crystallized  the  mother-liquor 
is  separated  by  filtering  with  the  aid  of  suction.  The  partially-dried 
residue  left  on  the  filter  is  then  boiled  with  another  120  c.c.  of  water, 
and  this  operation  is  repeated  as  often  as  may  be  necessary  for  remov- 
ing the  whole  of  the  cinchonidine.  In  the  case  of  a  salt  containing  5 
per  cent,  cinchonidine  sulphate  at  least  three  such  operations  will  be 
requisite,  and  a  salt  containing  9  per  cent,  will  require  at  least  five  re- 
crystallizations.  The  mother-liquors  obtained  in  the  first  three  opera- 
tions are  then  mixed  together  and  evaporated  at  a  moderate  heat 
almost  to  dryness ;  the  saline  residue  is  dissolved  by  a  few  drops  of 
dilute  sulphuric  acid,  and  the  solution,  made  up  to  the  volume  of  20 
c.c.  by  addition  of  water  and  ammonia  solution,  is  shaken  with  16  c.c. 
of  ether.  After  the  lapse  of  twenty-four  hours  the  crystals  that  may 
have  separated  from  the  ether  solution  are  collected  and  weighed.  The 
mother-liquors  from  subsequent  recrystallizations  are  evaporated  sepa- 
rately to  the  volume  of  about  8  c.c,  and  after  being  shaken  with  am- 
monia and  2  or  3  c.c.  of  ether  they  are  left  at  rest  for  twenty-four 
hours  for  the  separation  of  crystals. 
For  the  purpose  of  comparing  the  results  obtainable  by  this  method 
of  recrystallization,  and  by  the  bisulphate  method  of  testing,  the  fol- 
lowing experimental  data  are  given.  No.  I.  was  an  old  sample  of 
French  manufacture,  which  would  not  stand  the  test  of  the  present 
German  Pharmacopoeia,  and  No.  II.  a  sample  of  German  make,  which 
just  passed  that  test,  and  therefore  contained  an  amount  of  cinchoni- 
dine sulphate  that  was  within  the  limits  allowed : — 
Bisulphate  Test: 
I  
II  
Recrystallization  Test  : 
Mother-liquors. 
1,2,3.         4.  5.  6. 
Cinchonidine 
Crystals.  Total.  sulphate. 
Per  cent. 
I.   0*505   0-046   0-007    0  =  0-558  =  9'34 
II.     -262     -015     -0  -277  4*64 
Cinchonidine 
Crystals.  sulphate. 
Per  cent. 
...0-534    =  8-94 
...  -302    =    5  09 
From  this  comparison  it  appears  that  both  methods  of  testing  fur- 
nish results  which  agree  in  a  satisfactory  manner,  and  consequently  it 
