Amjui°y,ri887harm*}  Weights  and  Measures  in  Liquid  Preparations.  329 
more  time  and  labor  have  been  spent  in  discussing  "parts  by  weight" 
since  the  issue  of  the  Pharmacopoeia  than  before.  Yet  it  needs  very 
little  time  to  prove  that  after  five  years'  trial  before  the  country  the 
u  consensus  of  pharmaceutical  opinion"  is  greatly  in  favor  of  weighing 
solids  and  measuring  liquids. 
That  there  are  advantages  in  the  system  adopted  in  the  Pharmaco- 
poeia, no  one  can  gainsay;  the  operator  can  choose  from  the  formula 
whatever  denomination  he  desires  and  by  substitution  for  parts  he  can 
use  grammes,  drachms,  grains,  scruples,  pounds,  kilogrammes,  or  any 
other  weights.  The  adoption  of  the  centesimal  ratio  of  expressing  the 
proportions  of  the  ingredients,  whilst  not  necessary  to  the  success  of 
the  principle  of  using  parts  by  weight,  was  rendered  desirable  in  view 
of  the  anticipated  use  of  the  metric  system,  and  so  the  method  adopted 
in  the  Pharmacopoeia  undoubtedly  favored  the  use  of  the  gramme 
and  its  multiples,  because  the  multiplication  and  division  were  effected 
by  decimals.  There  are  many  operations  in  the  laboratory,  which  are 
more  conveniently  performed  by  weighing  the  liquids ;  for  instance 
in  making  a  barrel  of  soap  liniment,  it  is  very  convenient,  and  usually 
more  accurate  to  roll  the  barrel  on  the  platform  scales,  tare  it,  and  to 
pour  the  liquids  in  successively  until  the  proper  weight  is  indicated, 
and  after  adding  the  solids  and  inserting  the  bung,  the  barrel  may  be 
rolled  backward  and  forward  until  solution  is  effected.  Then  again  in 
the  case  of  adhesive,  corrosive  or  acid  liquids,  it  is  far  more  convenient 
to  weigh  them  than  to  use  measures.  But  it  must  be  remembered  that 
the  vast  majority  of  those  who  employ  the  pharmacopoeia  use  fluid- 
ounces  and  not  gallons  or  barrels  as  their  units,  whilst  the  few  ad- 
hesive, corrosive,  or  acid  liquids  that  must  be  mixed  together,  consti- 
tute a  small  class  which  may  properly  form  exceptions  to  the  rule. 
Where  small  quantities  of  liquids  are  concerned,  it  cannot  be  denied 
that  graduated  measures  still  continue  to  be  used  to  as  large  an  extent 
.as  ever,  and  so  long  as  physicians  continue  to  prescribe  liquids  by 
measure  and  administer  them  in  teaspoons  and  tablespoons,  just  so 
long  will  graduated  measures  be  employed,  and  it  would  be  illogical 
and  useless  to  expect  prescriptions  to  be  compounded  by  weight 
unless  convincing  arguments  can  be  presented  to  prove  the  greater 
convenience  and  accuracy  of  weighing  liquids.  Now,  so  far  as  con- 
venience and  practicability  are  concerned,  it  must  be  admitted  that 
the  glass  graduated  measure  maintains  its  supremacy ;  and  as  to  accu- 
racy, it  has  been  well  contended  that  there  is  just  as  much  liability  to 
