Aj;nuaryPih899m-}     Standard  for  Belladonna  Plaster.  33 
Committee  as  to  the  pharmacopoeial  requirements,  in  that  extract 
of  belladonna  leaf  was  mixed  with  twice  its  weight  of  plaster  mass, 
instead  of  mixing  it  with  four  times  its  weight  of  mass,  as  demanded 
by  the  Pharmacopoeia.  This  is  based  upon  the  statement  in  the 
report  above-mentioned,  that  in  order  to  test  the  accuracy  of  the 
method  used  for  the  valuation  of  the  commercial  plasters,  an 
assayed  extract  of  belladonna  leal  was  mixed  with  twice  its  weight 
of  a  plaster  vehicle  consisting  of  rubber,  resins,  etc.,  the  mixture 
then  being  assayed  to  determine  whether  or  not  all  alkaloid  could 
be  recovered.  It  will  be  apparent  to  any  one  reading  the  report 
attentively,  that  the  mixture  was  made  merely  for  this  purpose,  and 
not,  as  it  is  made  to  appear  in  the  pamphlet  of  Messrs.  Johnson  & 
Johnson,  to  prepare  a  typical  standard  plaster.  It  would  not  have 
been  possible  to  prepare  a  plaster  meeting  the  implied  requirements 
of  the  Pharmacopoeia  from  the  extract  used,  by  adhering  to  the 
proportions  directed,  since  its  strength,  about  1*15  per  cent,  of  alka- 
loids, was  considerably  lower  than  might  reasonably  be  expected 
from  a  leaf  extract  of  average  quality.  The  U.  S.  Pharmacopoeia  of 
1890  requires  the  plaster  to  contain  20  per  cent,  of  extract  of  bella- 
donna leaf,  this  standard  being  approximately  the  same  as  that  of 
the  U.  S.  Pharmacopoeia  of  1880,  which  demanded  that  the  plaster 
represent  its  own  weight  of  belladonna  leaf.  Since  experience  has 
shown  the  average  yield  of  extract  from  the  leaf,  when  made  with 
the  official  menstruum,  to  be  about  22  per  cent.,  the  two  standards- 
differ  but  little,  and  as  a  specimen  of  belladonna  leaf  containing  less 
than  0*3  per  cent,  of  alkaloids  is,  by  general  consent,  regarded  as 
below  the  average,  a  belladonna  plaster  falling  much  below  this 
strength  must  also  be  regarded  as  deficient. 
No  attempt  was  made  by  the  writer  to  fix  a  definite  standard  of 
strength  in  the  report  referred  to,  but  in  commenting  on  a  tabulated 
list  of  analyses  of  commercial  plasters  included  in  it,  it  was  stated 
that  a  certain  number  of  the  samples  assayed  were  much  below  the 
U.  S.  Pharmacopoeia  standard  of  strength.  As  these  samples  were 
found  to  contain  from  0  042  to  0*125  per  cent,  of  alkaloids  only,  no 
one  can  with  reason  object  to  the  characterization  of  these  as  being 
below  the  implied  pharmacopoeial  requirements. 
The  writer  wishes  to  take  this  opportunity  to  correct  any  false 
impression  that  may  possibly  have  been  created  in  the  minds  of 
some  of  those  reading  the  last  paragraph  of  a  note  on  belladonna 
