Am'ju°iy?i?9h9arnJ'}    Acetic  Acid  in  Extracting  Drugs.  317 
and  well  shaken,  the  watery  solution  from  the  large  beaker  added, 
again  shaken  for  five  minutes,  allowed  to  separate,  drawn  off  and 
poured  off  as  before,  and  this  washing  is  repeated  a  third  time. 
The  watery  portion  is  now  tested  and  should  be  found  bitter-free, 
or  be  again  ether-washed.  The  ether  solutions  in  the  tared  beaker 
are  boiled  off  on  the  bath  and  leave  a  varnish-like  residue  of  an 
amber  color,  consisting  of  total  alkaloids  and  a  little  insoluble  waxy 
matter.  This  is  weighed  in  order  to  get  the  approximate  percent- 
age of  alkaloids,  and  for  each  1  per  cent,  of  these  crude  alkaloids  5 
c.c,  of  decinormal  acid  is  run  into  the  beaker  from  a  burette  and 
10  c.c.  of  water  added.  But  these  alkaloids  are  difficult  and  slow  to 
dissolve  in  the  acid,  so  that  time  is  saved  by  dissolving  them  in  3  or 
4  c.c.  of  ether  by  rotary  agitation  before  the  acid  is  run  in.  When 
the  acid  is  run  in,  the  waxy  and  fatty  matters  are  precipitated  and 
a  stirrer  and  warming  are  then  used  to  free  this  precipitated  matter 
from  alkaloids  and  to  drive  off  the  ether.  The  alkaloids  are  thus 
converted  into  acid  salts  and  dissolved,  and  the  insoluble  matters 
are  deposited  on  the  sides  and  bottom  of  the  beaker.  If  the  nearly 
clear  solution  be  poured  off  and  the  beaker  and  residue  be  dried, 
weighed  and  the  weight  be  subtracted  from  the  weight  of  crude 
alkaloids,  the  remainder  will  be  within  o-i  or  02  per  cent,  of  the 
weight  of  pure  alkaloids,  and  thus  will  be  a  useful  check  upon  the 
titration  that  is  to  follow. 
In  the  titration  now  to  be  described  litmus  paper  is  used  as  the 
indicator,  and  if  the  paper  be  good  and  be  well  managed  the  indi- 
cation is  sufficiently  accurate,  reaching  to  the  second  decimal  place 
of  percentage.  The  paper  is  used  in  strips  0  5  cm.  wide,  some  of 
deep  blue,  some  neutral,  and  about  a  centimetre  of  the  end  of  the 
strip  is  wetted  for  the  indication. 
Decinormal  potassium  hydrate  solution  is  dropped  from  a  burette 
into  the  acid  solution  of  the  alkaloids  with  stirring  and  frequent 
testing  until  the  solution  fails  longer  to  change  blue  litmus  paper. 
When  the  blue  strip  is  just  touched  to  the  surface  of  the  solution, 
the  liquid  rises  in  the  paper  to  about  a  centimetre.  As  the  neutral 
point  is  approached  the  end  will  be  blue  with  a  red  or  reddish  band 
above  the  blue,  but  when  it  is  reached  the  whole  wetted  part  will 
be  unchanged  blue.  Then  a  strip  of  neutral  litmus  paper  has  the 
end  wetted  with  distilled  water  for  about  a  centimetre,  and  this  end 
is  just  touched  to  the  surface  of  the  solution  and  held  there  for  a 
