Aifi.  Joui .  Pliai  Ji  \ 
June,  1881.  J 
JEmuIsions. 
289 
oil  and  similar  preparations,  in  which  large  quantities  of  oil  are 
desired  to  be  emulsified  with  as  small  a  quantity  of  giun  as  possible. 
C.  Yolk  of  Egg. — This  substance  is  also  seldom  used.  In  the 
preparation  known  as  St.  John  Long's  Liniment  this  binding  medium 
is  employed  and  is  well  adapted  for  emulsifying  oil  of  turpentine, 
because  the  fixed  oil  of  egg  combines  with  the  essential  oil  of  turpen- 
tine and  in  this  way  renders  emulsification  easier. 
Another  instance  where  yolk  of  egg  has  the  office  of  binding  medium 
is  the  officinal  Mistura  Chloroformii,  which  might  be  called  an  emul- 
sion, as  a  substance  nearly  insoluble  in  water  is  suspended  in  it  by 
means  of  yolk  of  egg. 
D.  Tincture  of  Soap  Bark. — The  attention  of  the  profession 
has  in  the  last  two  years  very  frequently  been  called  to  the  emulsifying 
properties  of  this  tincture,  though  this  preparation  was  occasionally 
used  for  the  formation  of  emulsions  since  1850.  All  the  emulsions 
made  by  means  of  tincture  of  soap  bark  separate  into  two  layers, 
which  are,  however,  easily  and  thoroughly  mixed  on  agitation. 
Class  2.  jEinulsions  of  semi-liquid  and  solid  balsams,  solid  fats  and 
camphors. 
This  class  of  emulsions  is  not  an  important  one. 
On  the  continent  of  Europe  and  in  England  pharmacists  are  some- 
times called  upon  to  prepare  emulsions  of  wax,  spermaceti  and  butter 
of  cacao,  for  lotions  for  the  hands,  etc.  These  fats  are  emulsified  by 
melting  in  a  mortar  one  part,  triturating  it  with  one  part  of  gum  ara- 
ble, and  then  adding  gradually  one  part  and  a  half  of  water  of  a 
temperature  of  90°  to  95°C.  and  stirring  until  thoroughly  combined. 
After  cooling,  the  emulsion  is  to  be  diluted  very  carefully  to  the 
desired  extent. 
This  operation  is  greatly  facilitated  by  the  addition  of  a  small  quan- 
tity of  borax,  and  if  the  preparation  is  intended  for  a  lotion,  this 
addition  is  a  very  good  one,  not  only  on  account  of  its  cleansing  pro- 
perties, but  also  because  borax  coagulates  a  mucilage  of  gum  arable, 
and  consequently  gives  the  preparation  more  body  and  stability.  One 
scruple  of  borax  is  sufficient  for  one  fluidounce  of  emulsion. 
In  the  same  way  as  solid  fats,  the  semi-liquid  and  solid  balsams 
may  be  emulsified.  Sometimes  they  are  dissolved  in  alcohol,  ether, 
chloroform  or  other  solvents,  and  then  they  would  have  simply  to  be 
treated  as  the  substances  mentioned  under  Class  1. 
Camphor  is  either  emulsified  by  dissolving  it  in  the  smallest  possi- 
