144 
Kernels  Quinine  Test. 
(  Am.  Jour.  Pharm. 
\      March,  1887. 
But  when  it  is  requisite  to  allow  manufacturers  a  certain  tolerance, 
and  in  consequence  of  this  to  ascertain  whether  the  salt  to  be  tested  is 
contaminated  with  foreign  substances  in  proportion  above  or  below  a 
fixed  limit,  the  case  is  no  longer  one  of  the  same  nature.  Some  very 
simple  calculations  will  suffice  to  show  this,  and  I  shall  for  this  pur- 
pose make  use  only  of  the  figures  furnished  by  M.  Oudemans,  and 
take  for  illustration  the  experiments  made  under  the  conditions  of 
dilution  for  which  those  figures  have  been  found. 
In  calculating  for  a  length  of  column  of  2  decimetres  the  deviation 
produced  by  0*436  gram  of  the  alkaloid  sulphate  dissolved  in  20  cc. 
of  absolute  alcohol  the  following  results  are  obtained.  The  deviation 
is  av= — 6*8(3°*  for  the  neutral  crystallized  quinine  sulphate,  and  for 
the  neutral  crystallized  cinchonidine  sulphate  it  is  «D=— 5*17°. f 
Therefore  the  diviation  produced  by  any  mixture  of  these  two  sul- 
phates will  lie  between  these  two  extreme  limits.  One  hundredth  part 
of  the  difference  between  the  two  figures  (1.69°)  would  be  0*0169, 
and  that  would  be  the  influence  exercised  by  the  presence  of  1  per 
x?ent.  of  cinchonidine  sulphate,  more  or  less  in  quinine  sulphate.  I 
believe  that  this  relation  between  17  thousandths  of  a  degree  and  each 
hundredth  part  of  cinchonidine  sulphate  more  or  less  in  the  mixture 
will  render  sufficiently  appreciable  the  delicacy  of  this  method  of  test- 
ing. But  the  method  has  still  another  defect  of  very  much  greater 
significance. 
If  pure  quinine  sulphate  be  mixed  with  one  hundredth  part  of 
quinidine  sulphate,  a  highly  dextrogyrate  salt,  the  deviation  calculated 
for  the  same  conditions  would  be  for  «D  =  -6*701°,  %  and  that  is  precisely 
*    _  aolp  157-4x2x0-436 
v  20 
f       aolp  118-7X2x0-436 
lD  — 
-6-86°. 
-5-17c 
v  20 
"d/       0-99x0-436  «d/0-01x0-436 
v  v 
0-4316  X  2  xl-574    0-0044  X  2  X  211  5 
20  20 
'd  =  —  6-793  X  0-09  2=-6701°. 
