102  MEDICINAL  ACONITIA  AND  ITS  SUBSTITUTES. 
gallons  have  slowly  passed,  or  until  the  root  is  so  far  exhausted 
that  the  passing  liquid  has  little,  if  any  taste  of  aconite.  To 
the  tincture  thus  formed,  add  an  ounce  of  lime,  previously 
hydrated  and  in  powder,  and  agitate  them  together,  separate 
the  precipitate  which  forms,  by  straining  through  a  close  cloth, 
and  saturate  the  liquid  with  diluted  sulphuric  acid  till  slightly 
acid.  Filter  the  liquid  through  a  close  filter  and  distil  off  the 
the  alcohol,  until  the  remaining  liquid  measures  about  a  pint 
and  a  half.  Remove  any  fixed  oil  which  may  separate  on  stand- 
ing, and  having  continued  the  evaporation  to  a  syrupy  consist- 
ence, agitate  it  well  with  four  fluid  ounces  of  ether  in  a  suitable 
bottle,  and  decant  the  ether  when  it  has  separated.  Then  add 
the  solution  of  ammonia  in  excess,  agitate  thoroughly,  wash 
the  mixture  with  repeated  portions  of  ether,  by  agitation  and 
decantation,  and  having  mixed  these  last  ethereal  liquids,  allow 
the  ether  to  evaporate  spontaneously  from  a  capsule,  until  the 
aconitia  remains  as  a  dry  amorphous  shining  residue,  which 
should  be  removed  from  the  capsule,  powdered  and  preserved 
for  use  in  a  stopped  vial. 
As  thus  obtained,  aconitia  is  a  powder  of  greenish  or  brownish- 
white  color,  uncrystallized,  very  soluble  in  alcDhol,  ether  and 
chloroform,  saturates  acids,  and  has  a  strong  alkaline  reaction. 
It  irritates  the  nose  powerfully  when  a  minute  particle  is  in- 
haled, but  does  not  excite  sneezing. 
Modes  of  using  Aconitia. — When  aconitia  is  to  be  employed 
in  the  form  of  an  ointment,  its  activity  may  be  much  increased 
by  adding  to  it  a  sufficiency  of  acetic  acid  to  salify  it,  w^hich 
renders  it  more  readily  absorbable  in  contact  with  the  skin. 
The  powder  should  first  be  triturated  with  a  few  drops  of 
alcohol  and  the  acid  added  to  this,  in  the  proportion  of  a  drop 
of  acetic  acid  to  each  grain  of  the  alkaloid. 
Glycerole. — When  aconitia  is  mixed  v/ith  a  slight  excess  of 
acetic  acid,  it  readily  dissolves  in  glycerin,  and  in  this  state  may 
be  applied  by  friction  to  the  surface  requiring  its  aneesthetic 
action.  The  proportion  of  the  alkaloid  to  each  preparation, 
must  be  regulated  by  the  prescriber ;  two  or  three  grains  to 
the  drachm  of  prepared  lard  is  a  maximum  strength  for  the 
ointment,  and  from  this  down  to  one  grain. 
