102 
WEIGHTS  OF  THE  PHARMACOPOEIA. 
of  quantity  for  all  the  mixtures  and  solutions  of  the  Pharma- 
copoeia. 
In  the  apportionment  or  distribution  in  pill  preparations  of 
the  Pharmacopoeia,  a  similar  reform  seems  greatlj  needed.  The 
quantities  of  different  pills  indicated  by  the  several  formulas  are 
properly  varied  according  to  the  nature  and  use  of  the  prepa- 
ration;  but  they  are  most  usually  ordered  in  numbers  having  a 
decimal  expression.  Thus,  among  the  more  common  numbers 
will  be  found  80,  120,  180,  200,  240,  480,  &c— more  incon- 
venient numbers  than  which  for  practical  division  could  not 
easily  be  selected.  To  make  a  given  mass  into  180  pills,  for 
instance,  is  quite  a  troublesome  task,  notwithstanding  the  great 
variety  of  factors  this  number  can  boast: — (2x90; — 3x60; — 
4x45; — 5x36;— 6x30,  &c.)  The  required  number  may  be 
obtained  either  by  dividing  the  mass  into  12  parts  of  15  pills 
each,  or  into  10  parts  of  18  pills  each,  or  what  would  be  the 
more  usual  course,  into  9  parts  of  20  pills  each.  But  to  divide 
into  three  parts,  and  each  of  these  again  into  three  parts,  would 
be  very  tedious  and  inconvenient;  or  to  weigh  the  whole  mass, 
and  then  weigh  off  one-ninth  part,  and  divide  into  pills,  and  so 
on  successively,  would  leave  the  last  portion  sensibly  too  light 
by  the  drying  which  would  take  place  in  the  mean  time.  The 
pills  would  thus  be  found  to  be  of  very  unequal  value  or  strength; 
and  the  only  way  to  avoid  this  would  be  to  complete  the  nine 
independent  weighings  at  once. 
Now,  if  instead  of  a  system  of  division  so  tedious  and  difficult, 
we  made  use  of  that  simplest  and  most  natural  of  all  the  scales, 
— the  scale  of  fined  division,-— we  may  carry  the  bisection  to  any 
extent,  with  the  greatest  facility  and  accuracy,  and  without  any 
reference  to  the  absolute  weights  of  the  several  parts.  It  is  the 
peculiar  merit  of  this  scale  that  we  can  divide  by  it  any  plastic 
mass,  or  any  given  quantity  of  powder,  (or  even  of  a  liquid,) 
into  halves,  quarters,  eighths,  sixteenths,  thirty-seconds,  or 
sixty-fourths,  &c,  with  perfect  precision  and  with  expedition, 
without  the  use  of  any  weights  whatever;  an  advantage  that  can 
be  alleged  of  no  other  system  of  division.  Moreover,  in  the  case 
of  a  large  pill-mass,  it  would  evidently  be  of  no  consequence  to 
the  equality  of  the  resulting  pills  what  time  had  elapsed  between 
the  first  and  last  division,  or  how  much  weight  had  been  lost  in 
the  interim  by  evaporation, 
