AmjJu°ner;i9?3arm"}     Pharmacy  of  Liquid  Petrolatum.  261 
Taking  up  the  first  of  these  uses,  we  naturally  turn  to  the  emul- 
sion as  the  best  form  for  its  administration,  and  a  review  of  journals, 
for  a  number  of  years  past,  has  shown  that,  although  several  formu- 
las have  been  published,1  a  wide  divergence  of  opinion  has  existed, 
for  they  are  variously  directed  to  be  prepared  from  petroleum,  pet- 
rolatum, white  vaseline  or  soft  paraffin,  and  with  a  difference  of 
from  12%  per  cent,  to  33  per  cent,  of  oil.  The  majority,  however, 
have  favored  25  per  cent,  of  the  liquid  petrolatum,  and  the  formulas 
offered  are  based  upon  that  strength. 
A  number  of  initial  experiments  were  made  to  determine  the  best 
emulsifying  agent  and  preservative,  and  the  results  are  here  pre- 
sented in  some  detail. 
Acacia  first  being  tried,  it  was  found  that  the  proportions  usually 
suggested  for  the  Continental  method,  4  parts  of  oil,  2  parts  of 
water  and  1  part  of  acacia,  would  not  produce  an  emulsion;  but  fur- 
ther experiments  showed  that  if  equal  parts  of  water  and  liquid 
petrolatum  and  y±  part,  or  better,  y2  part  of  acacia  be  taken,  an 
emulsion  could  be  formed  quickly  and  easily  by  the  Continental 
method. 
I  may  say  here  that  this  formula,  for  either  stability  or  ease  ot 
manipulation,  has  not  been  improved  upon  by  subsequent  experi- 
ments, although  it  was  found  necessary  to  add  a  preservative. 
To  determine  this  point,  a  number  of  trials  were  made  of  the  several 
available  preservatives,  and  the  preparations,  after  standing  about 
eight  months,  show  that  either  8  per  cent,  of  glycerin,  5  per  cent,  of 
alcohol,  sodium  benzoate  (8  grains  to  1  pint),  benzoic  acid  (8  grains 
to  1  pint),  oil  of  wintergreen  (32  minims  to  1  pint),  or  a  mixture 
of  oil  of  wintergreen  with  other  oils  like  oil  of  sassafras  and  oil  of 
bitter  almond,  will  prevent  decomposition. 
As  the  result  of  these  experiments,  the  two  following  formulas 
have  given  the  most  satisfaction  and  can  be  recommended  : 
EMULSION  OF  LIQUID  PETROLATUM  ( PLAIN). 
Liquid  petrolatum,  J  iv 
Acacia,  powdered,  Jij 
Oil  of  wintergreen,  minims  xxxij 
Water,  sufficient  to  make  Oi. 
1  Merck's  Rep.,  1895,  p.  29;  Chem.  and  Drug.,  No.  887,  p.  611;  West.  Drttg., 
1902,  p.  392;  Meyer  Bros.''  Drug.,  1900,  p.  267. 
