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Emulsions. 
(  Am.  Jour.  Pharm. 
t       July,  1878. 
EMULSIONS. 
By  Ph.  H.  Dilg,  Ph.G. 
In  preparing  emulsions,  German  apothecaries  generally  employ  the 
relative  quantity  of  gum  and  oil  officinal  in  the  German  Pharmacopoeia  ; 
many  differ,  however,  in  regard  to  the  exact  proportion  and  time  of 
adding  the  first  portion  of  water.  Some  mix  at  once  4  parts  of  water, 
4  of  oil  and  2  of  gum  ;  others  first  mix  4  parts  of  oil  with  2  parts  of 
gum,  and  then  add  4  parts  of  water  at  once  ;  still  others  follow  either 
one  of  the  above  methods,  with  the  exception  of  using  only  3  instead 
of  4  parts  of  water  as  the  first  portion.  I  have  experimented  with 
each  one  and  came  to  the  conclusion  that,  though  there  is  no  material 
difference  in  the  result,  the  second  is  the  most  advantageous  mode.  It 
is  preferable  to  the  first  for  being  less  liable  to  afford  the  gum,  espe- 
cially when  in  fine  powder,  opportunity  to  clog,  and  it  is  more  easily 
manipulated  than  the  third  method,  since  the  larger  amount  of  water 
facilitates  the  division  or  spread  of  each  particle  of  gum,  thereby 
expediting  the  thorough  combination  of  the  mixture.  After  mixing 
intimately  half  as  much  gum  as  a  given  quantity  of  oil  or  balsam,  add 
at  once  the  same  quantity  of  water  as  oil,  and  triturate  until  a  crackling 
noise  is  produced,  which  indicates  that  the  oil  is  thoroughly  emulsion- 
ized  and  will  bear  any  amount  of  dilution  ;  it  is  one  of  the  principal 
points  to  be  observed  in  following  the  German  process.  As  far  as 
permanency  and  pure  milkiness  are  concerned  there  is  probably  no 
superior  emulsion  made  ;  it  has,  however,  the  decided  disadvantage  of 
requiring  too  much  gum.  Therefore,  whenever  a  larger  amount  of 
oil  is  required  to  be  emulsionized,  it  is  advisable  to  use  the  method 
which  has  found  much  favor,  at  least  among  Philadelphia  druggists, 
namely,  forming  a  mucilage  and  adding  oil  gradually,  with  much  less 
gum  than  is  generally  used.  I  have  succeeded  in  making  perfect 
emulsions,  which  will  remain  so  as  long  as  extemporaneous  mixtures 
are  generally  expected  to  stand  without  separating,  namely,  about  a 
week,  when  they  will  commence  to  separate  into  layers,  without  liber- 
ating the  oil,  and  a  slight  shake  will  recombine  them.  I  make  a 
a  mucilage  with  f^iv  water  and  3i  gum  and  gradually  (not  necessarily 
slowly)  add  f^i  oil ;  after  these  are  well  combined  enough  water  is 
added  to  make  fsii,  after  which  the  mixture  will  bear  copious  dilution. 
It  is  a  mistake  to  think  that  the  mucilage  must  be  thick,  as  this  renders 
it  necessary  to  add  the  oil  and  balance  of  water  alternately.    In  trying 
