534  PREPARATION  OF  EMPLASTRUM  ASSAFCETIDiE. 
gum-resins,  but  was  required  in  larger  proportion  than  chloro- 
form. Brandes  found  two  resins  in  assafetida  ;  one  of  which, 
existing  in  small  proportion,  was  insoluble  in  ether  and  tasteless, 
and,  although  the  residue  left  by  ether  is  more  bulky  than  that 
of  chloroform,  its  much  lower  cost  is  greatly  in  its  favor  as  a 
menstruum.  The  great  volatility  of  both  these  liquids  enables  the 
evaporation  to  be  spontaneous,  if  operating  in  small  quantities, 
or,  if  the  liquids  are  to  be  recovered  by  distillation,  permits  of 
its  being  done  by  a  water-bath,  without  injuriously  volatilizing 
the  essential  oils. 
But  the  assafetida  plaster  frequently  met  with  differs  from 
that  of  the  IT.  S.  Pharmacopoeia,  by  containing  the  gummy  as 
well  as  resinous  part  of  the  drug, — -apparently  being  made  by 
liquifying  the  assafetida  by  a  hydro-alcoholic  menstruum  and 
straining  out  any  gross  impurities,  and  then  concentrating  to  a 
.  thick  consistence  before  incorporating  with  the  plaster  and  wax, 
Such  plaster,  when  melted  with  the  plaster  spatula,  is  apt  to 
coagulate  or  separate,  owing  to  the  infusibility  of  the  gummy 
particles. 
In  view  of  these  results,  the  following  modification  of  the 
officinal  formula  is  offered  for  acceptance  : — 
Take  of  Assafetida, 
Lead-plaster,  each,  twelve  ounces. 
Galbanum, 
Yellow-wax,  each,  six  ounces. 
/(Ether,  three  pints. 
Alcohol,  a  pint. 
Thoroughly  bruise  the  gum-resins  in  a  mortar,  put  them  in  a 
suitable  bottle,  pour  on  the  ether,  and  agitate  frequently  until 
the  oleo-resinous  portion  is  dissolved  and  a  fawn-colored  pulver- 
ulent residue  remains  as  a  sediment.  Having  placed  a  close 
cotton  flannel  or  lint  filter  in  a  suitable  funnel,  empty  the 
contents  of  the  bottle  in  it  and  cover  it  closely.  As  the  ethereal 
liquid  gradually  disappears,  pour  on  the  alcohol,  and  when  it 
has  ceased  to  pass,  evaporate  or  distil  the  filtered  liquid  with  a 
gentle  heat  until  it  acquires  the  consistence  of  honey  and  has 
lost  an  ethereal  odor.  Then,  having  melted  the  lead-plaster 
and  wax  at  a  moderate  temperature,  add  the  oleo-resins  and 
stir  constantly  until  cooled.  Thus  prepared,  assafetida  plaster 
has  a  fawn  color  when  recent,  which  darkens  by  age  and 
