.?^«i,jom-.r^mrm.|  PJiannacoj^adal  Preparations.  501 
At  first  sig:]it  it  would  seem  far  easier  to  assimilate  Pharmacopreias 
-of  continental  Europe  than  those  of  Great  Britain  and  of  the  United 
States,  because  of  tlie  difference  in  the  usage  of  the  two  countries  in 
regard  to  weigliing  and  measuring,  and  also  because  of  the  difference 
between  the  weights  and  measures  of  those  countries.  In  the  United 
States  liquid  acids  and  oils  are  weighed,  but  all  other  liquids  are  mea- 
sured as  in  England.  When  the  British  Pharmacopa^ia  was  intro- 
duced, the  troy  weight  that  liad  hitherto  been  used  in  England  and 
Scotland  had  to  give  way  to  the  avoirdupois  weight  then  used  in  Ire- 
land. The  imperial  measure  was  already  being  used  in  England, 
Scotland  and  Ireland  for  liquids.  Thus  the  avoirdupois  ounce,  weigh- 
ing 437J  grains,  and  the  fiuidounce — or  the  volume  of  distilled  water 
weighing  at  a  temperature  of  60°F.  4o7h  grains — became  the  stand- 
ards of  weight  and  measure  in  tlie  British  Pharmacopoeia. 
The  fluidounce  is  divided  into  480  minims,  and  so  far  as  i-egards 
subdivisions  corresponds  to  the  ounce  troy  of  480  grains  formerly  in 
use,  but  as  the  minim  does  not  ^veigh  a  grain,  the  fluidrachm  of  60 
minims  is  only  equal  to  Sly^-^-  grains.  However,  all  liquids  except 
mercury  are  ordered  by  the  British  Pharmacopoeia  to  be  measured, 
and  in  all  prescriptions  tliey  are  dispensed  by  measure.  All  liquid 
medicines  are  ordered  to  be  taken  by  measure,  so  that  a  consistency 
runs  through  the  whole  arrangement. 
Tlie  United  States  Phnrmaco])oeia  retains  the  use  of  the  troy  weight, 
the  wine  pint  of  16  ounces  weighing  7291^^  grains  and  the  fluidounce 
weighing  455^^  grains  in  the  case  of  water  at  a  temperature  of  60°F. 
Therefore  the  United  States  liquid  measure  differs  from  the  British 
liquid  measure  in  each  of  its  divisions. 
On  the  continent  of  Europe  all  liquids,  as  well  as  solids,  are  weighed 
in  dispensing,  and  in  the  formula?  of  the  Pharmacopeias  the  same 
system  is  followed.  Sometimes  tlie  pro})ortions  are  expressed  in 
grams,  and  sometimes  in  ])arts,  but  always  by  weight,  so  that  in  the 
case  of  a  tincture  ordered  to  be  made  with  1  part  of  the  drug  to  5 
parts  of  spirit  the  same  proportions  will  be  maintained  in  all  countries 
where  it  is  the  practice  to  weigh  everything.  But  1  ])art  of  drug  to  5 
parts  of  spirit  would  have  a  different  meaning  in  Great  Britain  and 
in  the  United  States  where  the  spirit  would  be  measured,  and  there 
would  even  be  a  further  difference,  since  the  measures  used  are  not  the 
same  in  the  two  countries. 
It  follows,  therefore,  that  one  of  the  first  steps  towards  uniformity 
of  pharmaceutical  preparations  is  to  obtain  a  standard  in  parts  by 
weight,  say,  for  example,  1  ]mrt  of  a  drug  to  5  parts  of  spirit.  It 
would  not  be  necessary  to  alter-the  method  of  British  dispensing,  or 
the  directions  of  the  Pharmaco])ceia,  by  the  substitution  of  weighing 
for  measuring,  since  it  is  easy  to  determine  the  volume  equivalent  of 
a  given  weight  of  spirit,  and  to  regulate  the  strength  of  the  prepara- 
tion accordingly. 
