310  Relative  Strength  of  Certain  Preparations.  {^""jin^issT"" 
ON  THE  RELATIVE  STRENGTH  OF  CERTAIN  PREPAR- 
ATIONS OF  THE  OLD  AND  NEW  PHARMACOPOEIA. 
By  John  M.  Maisch. 
The  line  of  duty  mapped  out  by  the  Pharmacopoeial  Convention  of 
1880,  for  the  Committee  of  Revision,  necessitated  certain  changes  in 
the  processes  for  galenical  preparations.   The  instructions  under  which 
these  changes  had  to  be  made  comprised,  1.  The  abandonment  of 
measures  of  capacity  ;  2.  The  preparation  of  all  tinctures,  wines,  etc.^ 
in  which  a  slight  variation  of  dose  is  of  no  importance,  in  such  a 
manner  as  to  be  as  nearly  as  possible  of  a  uniform  strength,  (1  drug 
in  5,  10,  etc.,  tincture),  and  3.  The  avoidance  of  any  material  change 
in  strengtli  of  tinct.  aconiti  rad.,  tinct.  nucis  vomicae,  tinct.  opii  and 
tinct.  veratri  vir.    At  the  same  time  it  was  stipulated  that  all  liquid 
opium  preparations,  paregoric  excepted,  should  represent  10  per  cent, 
of  the  drug  if  found  advisable.    These  instructions,  which  in  the 
main  were  a  repetition  of  those  formulated  in  1870,  have  been  carried 
out,  and  a  table  has  been  appended  to  the  Pharmacopoeia,  (pp.  454 
455)  drawing  special  attention  to  the  difference  of  strength  in  the 
preparations  of  the  old  and  new  pharmacopoeia,  and  giving  this- 
diiference  in  a  simple  proportion,  one  of  the  factors  being  usually  10. 
On  carefully  examining  this  list,  it  will  be  found  that  the  majority  of 
the  preparations  there  enumerated  are  either  little  employed  or  have 
been  changed  in  strength  so  little  that  no  change  in  the  accustomed 
average  dose  is  required.    Under  the  clauses  cited  above  the  committee 
would  have  been  justified,  to  decrease  the  strength  of  tinct.  verat.  vir. 
from  55  (in  1870)  to  40  (instead  of  50)  per  cent,  so  as  to  make  it 
uniform  with  the  present  tinct.  aconiti  rad.,  or  the  latter  preparation 
might  have  been  increased  in  strength  from  47*6  to  50  (instead  of 
being  decreased  to  40)  per  cent.,  so  as  to  make  it  uniform  with  tinct. 
verat.  vir. 
The  table  referred  to  gives,  very  nearly,  the  changes  in  relative 
strength  correctly;  but  the  question  may  not  seem  to  be  out  of  place 
as  to  the  actual  difference  observed  at  the  dispensing  counter.  For 
practical  purposes  this  should  not  be  expressed  in  a  formidable  looking- 
proportion  or  in  a  percentage,  but  rather  in  a  concise  statement  of  the 
weight  of  the  drug  represented  in  a  given  measure.  For  it  is  by 
measures  that  most  physicians  order  liquid  medicines  to  be  dispensed,,, 
and  it  is   by  measures  that  most   prescriptions  are  compounded. 
