6  Substitute  for  Ethyl  Alcohol.        {A j^uary^oo.113, 
dilute  the  ammonia,  and  afterward  to  replace  the  alcohol  shaken  out 
by  the  chloroform  in  each  washing  of  the  alkaline  liquid.  When 
this  was  done  as  prescribed  in  the  process  the  separation  was  always 
prompt  and  complete,  and  the  chloroform  solutions  were  all  fairly 
clear. 
In  dissolving  the  alkaloids  out  from  the  crude  alkaloids  by  the 
decinormal  acid,  for  titration,  care,  patience,  agitation  and  a  hot 
water-bath  are  needed,  and  the  heat  must  be  sufficient  to  fuse  the 
resinous  matter  that  is  liable  to  hold  the  alkaloid  from  the  acid. 
The  principal  limitation  to  the  accuracy  of  the  new  process  is  in 
the  use  of  litmus  paper  as  an  indicator.  .  By  the  use  of  the  tip  end 
of  very  narrow  strips  very  little  of  the  solution  is  lifted  out  and  cut 
off  at  each  testing,  but  there  is  a  point  at  which  the  solution  does 
not  change  the  color  of  either  the  blue  dr  the  neutral  paper  where 
sometimes  one  and  sometimes  two  drops  are  required  to  produce  a 
faint  bluish  tinge  near  the  middle  of  the  wetted  end  of  the  neutral 
strip,  and  this  difference  of  one  drop  sometimes  affects  the  result 
in  the  second  decimal  place  of  percentage.  If  the  drops  be  divided, 
or  if  centinormal  alkali  be  used  when  the  neutral  point  is  near,  a 
closer  result  may  be  reached,  but  this  latter  introduces  a  compli- 
cation, and  only  reduces  the  error  by  about  one-half,  or  from  about 
I  in  60  to  I  in  120. 
COMPARATIVE  PERCOLATIONS. 
Five  hundred  grammes  of  the  same  No.  60  powder  of  the  un- 
peeled  belladonna  root  was  taken  for  each  of  two  parallel  percola- 
tions, the  two  being  carried  through  under  the  same  conditions  of 
time  and  management  as  nearly  as  practicable. 
For  one  percolation  the  U.S.P.  menstruum,  consisting  of  800  vol- 
umes of  91  per  cent,  alcohol  and  200  volumes  of  water,  was  used, 
and  for  the  other  10  per  cent,  acetic  acid. 
Each  portion  of  powder  was  moistened  with  200  c.c.  of  its  respec- 
tive menstruum,  both  were  digested  in  covered  vessels  for  twenty- 
four  hours — packed  in  syphon  percolators — fully  saturated  with 
menstruum,  and  digested  for  twenty  hours.  Then  the  syphons  were 
started  at  a  slow  rate  of  dropping,  and,  stopping  overnight,  were 
kept  nearly  parallel  to  the  end. 
The  percolates  were  received  in  100  c.c.  fractions  in  100  c.c.  nar- 
row-necked, marked  flasks,  and  were  weighed  to  I  centigramme. 
