INFLUENCE  OF  LIQUOR  POTASS^  ON   HENBANE,  ETC.  547 
served  that  a  very  minute  proportion  of  these  preparations  is  amply 
sufficient  to  induce  the  effect.  Of  course  these  extracts  and  tinc- 
tures are  liable  to  variation  in  strength,  acidity,  &c,  circumstances 
which  must  necessarily  produce  an  alteration  in  the  requisite 
amounts  of  liquor  potassse  required  for  complete  neutralization. 
With  even  the  best  extract,  however,  procured  from  one  of  the  first 
druggists  in  town,  it  was  found  that  nine  grains  were  destroyed  by 
the  above-named  quantity  of  potash.  Nine  grains  of  good  extract 
of  henbane  and  three  fluid  drachms  of  good  tincture  of  the  same 
may  be  considered  as  doses  of  the  drugs  which  few  practitioners 
would  prescribe ;  yet  these  are  destroyed  by  thirty  minims  of  liquor 
potassae,  proving  beyond  all  doubt,  that  in  the  proportions  pre- 
scribed in  actual  practice,  a  total  neutralization  of  effect  ensues.  To 
ascertain  the  required  time,  Dr.  Garrod  made  experiments  with  so- 
lutions of  atropine,  and  commenced  the  observation  shortly  after 
the  addition  of  the  potash.  In  an  hour  and  a  half  the  effect  on 
the  pupil  was  much  diminished,  and  in  two  hours  and  a  half  ceased 
altogether.  The  influence  of  the  alkali  in  preventing  the  occur- 
rence of  symptoms,  and  removing  the  same  when  large  medicinal 
doses  of  these  solanaceous  drugs  are  administered,  was  clinically 
illustrated  by  the  narration  of  several  cases,  in  which,  after  very 
decided  effects  had  been  induced  by  henbane  or  belladonna  prepa- 
rations, the  addition  of  a  very  small  quantity  of  liquor  potassaB  to 
the  draught  (the  patient  continuing  the  other  drugs)  quickly  caused 
the  cessation  of  the  symptoms;  and  again,  other  instances  where 
the  withdrawal  of  the  liquor  potassas  from  a  combination  was  fol- 
lowed by  the  occurrence  of  powerful  symptoms.  From  these  ob- 
servations and  experiments,  Dr.  Garrod  concluded  that  the  liquor 
potassse  possessed  the  peculiar  power  of  destroying  the  active  prin- 
ciples of  henbane,  belladonna,  and  stramonium,  even  when  in  very 
dilute  solutions,  and  that  the  combinations  frequently  prescribed  are 
utterly  incompatible  both  in  a  chemical  and  therapeutical  point  of 
view. 
In  answer  to  Dr.  O'Connor, 
Dr.  Garrod  stated  that  he  had  not  tried  the  effect  of  heat  in  his 
experiments,  but  he  had  no  doubt  that  an  increase  of  temperature 
would  increase  the  rapidity  of  decomposition. 
Dr.  O'Connor  said  he  had  observed  for  a  long  time  past  the  facts 
