M8  ON  ARNICA  PLASTER.  • 
pitch  half  a  troyounce.  Melt  the  resin  plaster  and  pitch  together 
in  a  water-bath,  add  the  extract  and  mix  thoroughly. 
This  plaster  is  uniform  in  texture,  spreading  quite  as  readily 
as  the  preceding,  and  is  of  a  more  desirable  consistence. 
Plaster  No.  III.  was  prepared  from  the  unofficinal  extract,  by 
taking  the  same  proportions  and  making  in  the  same  manner  as 
the  officinal.  This  plaster  spreads  readily,  but  the  same  objec- 
tion exists  as  in  the  officinal  or  No.  I.,  it  being  too  soft  at  the 
temperature  of  the  skin. 
Plaster  No.  IV.  The  proportions  in  this  plaster  vary  from 
the  officinal,  to  wit :    Take  of  the 
Alcoholic  extract  of  arnica  a  troyounce. 
Resin  plaster  three  troyounces. 
Made  as  the  preceding.    Its  general  properties  are  the  same  as 
Plaster  No.  I.,  only  lighter  in  color. 
Plaster  No.  V.  This  differs  from  the  preceding  and  is  sug- 
gested for  reasons  which  will  be  herein  stated.  The  following  is 
the  formula :    Take  of 
Alcoholic  extract  of  arnica,  a  troyounce. 
Resin  plaster,  two  troyounces. 
Burgundy  pitch,  120  grains. 
Cerate  of  Cantharides,  180  grains. 
Melt  the  plaster  and  pitch  together  in  a  water-bath,  and  add  the 
extract ;  finally  add  the  cerate  and  mix. 
This  plaster  presents  much  the  same  appearance  as  Plaster 
No.  II.,  spreads  as  readily  and  has  the  same  consistence.  In 
some  cases  this  may  be  preferable  to  the  ordinary  arnica  plaster, 
it  being  of  a  more  decided  rubefacient  character  and  yet  not 
containing  sufficient  cantharidis  to  produce  vesication. 
From  the  foregoing  experiments  I  discovered  that  the  addition 
of  Burgundy  pitch,  in  the  proportion  given  in  the  formula  for 
Plaster  No.  II.,  forms  a  very  adhesive  as  well  as  a  consistent 
plaster,  and  I  think  will  give  satisfaction  to  both  physician  and 
patient  who  may  have  occasion  to  prescribe  and  use  the  arnica 
plaster. 
In  concluding  my  essay,  I  was  in  the  hope  of  presenting  the 
opinion  and  experience  of  several  physicians  of  our  city,  to  whom 
