370 
WEIGHTS  AND  MEASURES,  ETC. 
The  sixteenth  part  of  a  pound  and  the  twentieth  part  of  a 
pint,  are  the  only  parts  of  the  system  in  which  the  weights  and 
measures  agree,  i.  e.  an  ounce. 
The  ounce  does  not  contain  a  whole  number  of  grains,  being 
equal  to  437.5  troy  grains,  and  therefore  incapable  of  division 
without  fractions  of  a  grain. 
The  use  of  it  is  discontinued  in  every  country  except  England 
and  America.  Mr.  Drinkwater  Bethune,  one  of  the  commission- 
ers on  weights  and  measures,  who  reported  in  1841,  says  of  it, 
"  that  it  is  difficult  to  conceive  a  system  more  thoroughly  well 
contrived  in  every  part  to  cause  intricacy  and  confusion."* 
In  the  year  1851,  when  the  last  edition  of  the  Dublin  Phar- 
macopoeia was  published,  the  avoirdupois  weight,  for  the  first 
time,  was  tried  in  medicine,  probably  on  account  of  the  ounce 
being  of  the  same  value  as  the  twentieth  part  of  the  imperial 
pint,  and  this  ounce  of  437.5  grains  was  divided  into  drachms 
of  54.7  grains,  and  scruples  of  18.22  grains.  New  weights  were 
expressly  manufactured  to  include  the  above  fractions  ;  the 
difficulty  of  prescribing  or  of  calculating  with  such  weights  must 
be  apparent,  to  say  nothing  of  the  different  value  of  weights 
bearing  the  same  name. 
If  the  committee  be  induced  to  adopt  the  avoirdupois  weight, 
the  whole  of  the  dispensing  weights  throughout  England  and 
Scotland  must  be  changed  and  all  prescriptions  written  and 
registered  prior  to  the  date  of  adoption  must  suffer  change  too, 
having  to  be  dispensed  with  weights  of  another  system,  and  of 
less  value. 
The  Apothecaries'  weight,  on  the  contrary,  is  divisible  into 
ounces,  drachms,  scruples,  and  whole  grains ;  has  been  used  in 
medicine  by  civilized  nations  from  time  immemorial;  France 
only  parted  with  it  when  the  Metrical  system  came  fully  into 
operation  as  a  national  system.  It  may  be  seen  in  the  Codex 
side  by  side  with  the  gramme  and  cubic  centimetre  in  the  for- 
mer edition  of  that  work  ;  a  very  nice  way  of  habituating  Phar- 
maceutists to  its  value  without  any  risk  of  confusion  or  leading 
to  error.  The  1  lb.  of  Holland,  and  of  the  German  Zollverein, 
is  equal  to  the  half  kilogramme,  or  500  grammes.  Sixteen 
ounces  of  our  Apothecaries'  weight  is  equal  to  the  same  thing. 
The  following  table  will  serve  to  show  with  what  facilities  we 
