LIQUOR  OPII  COMPOSITUS. 
127 
It  is  well  known  that  the  natural  salts  of  morphia  and  one  or 
two  of  the  other  alkaloids  of  opium  are  soluble  both  in  water  and 
in  alcohol,  whilst  a  large  proportion  of  the  inert  and  objection- 
able matters  are  rejected  by  each  of  these  menstrua ;  and  upon 
these  circumstances  are  based  the  supposed  advantages  of  this 
process.  The  water  as  a  menstruum  rejects  the  resin,  lignin, 
earthy  matters,  leaves,  seeds,  &c,  and,  used  cold,  rejects  almost 
all  the  narcotine  not  combined  as  a  soluble  salt,  and  one  or 
two  other  constituents  in  great  measure.  The  alcohol  rejects 
from  the  watery  extract  the  gum,  bassorin,  albumen,  and  some 
extractive  matters,  all  of  which  if  left  in  would  tend  to  ferment 
and  change  the  character  of  the  preparation  in  keeping,  whilst 
the  ether  washing  removes  the  oily  or  fatty  matters,  some  of  the 
codeia  and  other  matters.  Thus  depurated,  and  especially  when 
a  small  proportion  of  the  compound  spirit  of  ether  is  added, 
there  is  no  good  reason  why  the  preparation  should  not  keep 
indefinitely. 
The  application  of  a  process  of  assay  to  this  preparation,  how- 
ever desirable  in  view  of  uniformity  of  result,  has,  nevertheless, 
so  many  disadvantages  in  its  application  to  Pharmacy  in  gen- 
eral, that  it  is  very  doubtful  whether  its  use  will  accomplish  the 
purpose.  The  practical  difficulties  in  this  step  are  not  apparent 
at  sight ;  for  it  appears  that  when  reduced  to  absolute  mathemat- 
ical expression,  and  when  a  simple,  easy  process  of  management 
is  described  in  what  may  seem  to  be  superabundant  detail,  there 
could  be  little  possibility  of  inaccuracy.  Yet  to  any  one  not 
practised  in  such  processes,  the  difficulty  of  getting  the  assays  to 
agree  in  result  will  be  rather  surprising  and  discouraging,  and 
the  skill  to  be  acquired  before  absolute  results  are  attainable 
will  require  the  exercise  of  thorough  honesty  of  purpose  and  in- 
dustry of  pursuit.  It  is  nevertheless  absolutely  certain,  that  by 
perseverance  and  industry  reliable  results  can  be  obtained,  and 
that  there  are  a  large  number  of  pharmaceutists  who  by  educa- 
tion and  experience  are  well  qualified  to  perform  such  assays. 
When  using  the  process  for  the  first  time,  however,  it  is  not 
proper  for  any  one  to  depend  upon  the  result  of  a  single  assay 
as  directed  in  the  process.  Three,  at  least,  should  be  made, 
and  the  results  in  two  of  the  three  should  agree  within  «2  of  a 
grain,  and  the  mean  of  these  two  should  be  adopted.  Indeed, 
