44  Assaying  of  Alkaloidal  Drugs.       {  Am  jSJw.*"11* 
and  agitated  ;  I  cc.  ^  acid  is  taken  as  the  equivalent  of  0-0364  gm. 
alkaloid.    The  following  table  exhibits  the  results  : 
ALKALOIDS. 
By  Weighing.      By  Titrating.  Difference. 
Per  Cent.  Per  Cent.  Per  Cent. 
(1)  Unpeeled,   2*640  2*548  0*092  —  3*50 
(2)  Unpeeled,   2*685  2*611  0*074  =  2*01 
(3)  Peeled,    2*855  2*795  0*060  =  2*10 
(4)  Peeled,    2*780  2*725  0*055  =  2"lS 
The  difference  between  weighing  and  titrating  is  so  slight  that  the 
former  suffices  for  practical  pharmaceutical  purposes  and  enables 
the  assay  to  be  completed  in  less  than  three  hours.  It  is  important 
to  adhere  to  the  use  of  two  parts  ether  and  one  part  chloroform  in 
the  extraction,  since  a  larger  proportion  of  chloroform  increases  the 
yield  of  crude  alkaloids  (probably  caused  by  solution  of  the  gluco- 
side  loganin  ;  the  red  color  obtained  by  warming  the  crude  alka- 
loid with  dilute  sulphuric  acid  indicates  this),  and  hence,  a  greater 
difference  is  shown  between  the  weighed  and  titrated  alka- 
loids. The  use  of  a  greater  proportion  of  ether  risks  loss  of  alka- 
loids by  crystallization  since  the  alkaloids  are  almost  insoluble  in 
pure  ether.  The  fear  that  the  peeled  nux  vomica  contains  a  con- 
siderably higher  percentage  of  alkaloids  than  the  unpeeled  appears 
groundless  from  the  results  of  the  analyses  quoted  ;  for  pharmaceu- 
tical purposes  the  peeled  nux  vomica  is  preferable  because  of  its 
advantages  in  making  tincture  and  extract. 
Strychnos  bark  is  assayed  as  the  seeds  with  the  difference  that  the 
bark  is  first  percolated  with  a  mixture  of  ether  and  chloroform ; 
these  solvents  extract  only  traces  of  alkaloid,  but  leave  a  dark  green- 
ish brown  residue  of  chlorophyll,  fat,  wax,  etc.,  amounting  to  o  93 
per  cent,  of  the  bark.  The  yield  of  alkaloids  is  higher  than  in  the 
seeds,  three  determinations  giving  4-55-4*56  per  cent.;  the  alka- 
loids were  obtained  as  a  yellowish  varnish  which  required  treatment 
with  four  portions  of  alcohol  before  a  crystalline  appearance  was 
noted  ;  the  residue  was  obtained  of  constant  weight  after  consider- 
able difficulty  due  to  the  preponderance  of  brucine ;  by  a  method 
to  be  described  there  was  found  in  the  alkaloidal  residue,  strychnine 
33-6  per  cent.,  brucine  66  4  per  cent. 
The  dry  alcoholic  extract  of  nux  vomica  was  assayed  by  placing 
1-5  gm.  of  the  dry,  finely  powdered  extract  in  a  vial  of  150  gm. 
capacity  containing  10  gm  water,  agitating  until  a  uniform  mixture 
