546       INFLUENCE  OF  LIQUOR  POTASS^  ON  HENBANE,  FTC. 
the  chloroform  washed  with  a  little  distilled  water.  Each  portion 
was  evaporated  spontaneously  in  glass  dishes.  From  the  solution, 
to  which  carbonate  of  potash  had  been  added,  a  gummy  matter  was 
obtained  (soon,  however,  becoming  crystalline,  J  a  solution  of  which 
dilated  the  pupil  intensely ;  and  when  acidulated  with  hydrochloric 
acid,  and  chloride  of  gold  dropped  in,  gave  rise  to  the  beautiful 
plumose  crystals  of  the  double  chloride  of  gold  and  atropine.  From 
the  second  solution,  that  to  which  liquor  potassse  had  been  added,  a 
strong-smelling  substance  was  left,  on  the  evaporation  of  the  chloro- 
form, having  no  power  of  dilating  the  pupil,  and  giving  rise  to  no 
crystallization  with  the  gold  salt.  These  experiments  demonstrated 
beyond  doubt  the  absolute  destructive  agency  of  the  caustic  alkali 
upon  the  active  principles.  It  was  also  shown  that  most  other  alka- 
loids, as  morphia,  quinine,  cinchonine,  &c,  were  not  so  destroyed. 
To  show  the  ratio  which  must  exist  between  the  different  prepara- 
tions of  the  plants  and  the  fixed  alkali,  in  order  that  neutralization 
may  be  perfect,  Dr.  Garrod  gave  the  results  of  more  than  sixty  ex- 
periments and  observations  in  a  tabular  form,  from  which  it  appeared 
that  when  atropine  is  acted  upon  by  liquor  potassse,  the  destructive 
influence  of  the  latter  is  so  great,  that  less  than  twenty  minims  are 
required  to  neutralize  one  grain  of  the  former,  and  that  probably 
pure  potash  will  destroy  its  own  weight  of  atropine.  That  when 
belladonna  preparations  are  employed,  the  power  of  the  potash  be- 
comes weakened,1  from  the  causes  above  alluded  to— namely,  the 
natural  acidity  of  the  drugs,  and  the  necessity  of  first  displacing  the 
alkaloid  from  the  acid  with  which  it  is  combined;  still,  however,  it 
was  shown  by  the  table  that  fifteen  minims  of  liquor  potassse  will 
destroy  a  fluid  drachm  of  the  tincture,  and  that  twenty-five  minims 
are  sufficient  to  produce  the  same  change  in  five  grains  of  the  ex- 
tract ;  at  once  demonstrating  that  quantities  very  greatly  beyond  the 
medicinal  doses  of  these  drugs— indeed,  even  poisonous  amounts — 
are  rendered  quite  inert  by  very  moderate  addition  of  the  alkaline 
solution.  The  same  was  found  to  hold  good  in  the  case  of  daturine 
and  the  preparations  of  stramonium.  Ten  minims  of  liquor  potassse 
will  neutralize  a  drachm  of  tincture  of  henbane,  and  thirty  minims 
destroy  nine  grains  of  extract  of  henbane,  although,  when  ten  grains 
are  employed,  dilatation  will  often  ensue  from  a  small  portion  of  the 
extract,  less  than  one  grain  being  left  free  ;  and  it  should  be  ob- 
