ALKALOIDS  IN  THE  CINCHONA  BARKS. 
423 
are  redissolved.  I  have  made  the  following  experiments  for  as- 
certaining the  degree  of  solubility  of  the  cinchona  alkaloids,  and 
I  employed  two  kinds  of  commercial  liquor  ammoniae  of  dif- 
ferent strengths.  A,  Liq.  ammoniae  of  sp.  gr.  0-92.  B,  Liq. 
ammonias  of  sp.  gr.  0*96. 
1.  Quinine. — An  aqueous  solution  of  pure  sulphate  of  qui- 
nine, saturated  at  12°  to  15°  C.  contains,  as  has  been  pointed 
out  before,  not  always  constant  quantities  of  sulphate  of  qui- 
nine. A  great  many  determinations  of  solubility,  made  with 
pure  sulphates,  procured  from  various  manufacturers,  furnished 
the  proportions  1 :  770  to  1 :  738.  Most  of  the  sulphates  were 
soluble  in  750  to  755  parts  of  water  of  15°  C,  and  these  num- 
bers may  therefore  be  taken  as  average  numbers  of  solubility. 
According  to  Baup  sulphate  of  quinine  is  soluble  in  710  parts 
of  water  of  13°  C.  ;  according  to  Jobst  and  Hesse  in  793  to 
788  parts  at  from  6  to  9-5°  C. 
The  salt  which  served  for  the  following  determinations  of 
solubility  was  dissolved  in  752  parts  of  water  of  14-5°  C. 
5  c.  c.  of  this  solution  was  treated  in  a  test-tube  with  meas- 
ured quantities  of  Liq.  ammoniae,  till  the  cloudiness  which  at 
first  made  its  appearance  had  again  completely  disappeared, 
when  they  required 
Of  Liq.  Am.,  A.  Of  Liq.  Am.,  B. 
4-5  c.  c.  6-6  c.  c. 
4-6  «  6.5  « 
4-8  «  6.8  « 
4-7  «  6-6  « 
4-6  «  6-8  « 
4-8  «  6-7  « 
Samples  of  pure  sulphate  of  quinine,  which  were  a  little  more 
soluble,  required  a  few  tenths  more  of  both  test-liquids,  but  I 
never  met  with  a  pure  salt  which  required  more  than  5  c.  c.  of 
the  test  solution  A,  and  7  c.c.  of  the  test  solution  B,  per  5  c.  c. 
of  the  sulphate  solution. 
It  will  be  a  safe  course,  therefore,  to  adopt  in  every  case  the 
last  mentioned  limits  of  solubility  as  a  basis  in  the  estimation 
of  common  quinine  salts. 
2.  «  Quinidine. — The  solubility  in  water  at  15°  C.  of  the 
