^"Nov'"i88f™"}  Oleates  and  Oleo-Palmitates.  547 
myself  by  the  experiments  which  some  of  my  medical  friends  con- 
ducted in  hospitals  and  dispensaries.  As  oleates  prepared  in  this 
manner,  however,  possessed  the  disadvantage  of  a  high  price,  I  used 
consecutively  soap  of  the  oil  of  sweet  almonds,  and  ultimately  the 
ordinary  castile  soap,  with  quite  as  much  success. 
My  process  in  general  for  obtaining  oleates  is  as  follows :  One  part 
of  castile  soap  (sodium  oleo-palniitate)  is  dissolved  in  eight  parts  of 
water,  the  solution  so  obtained  is  allowed  to  cool  and  stand  for  24 
hours,  when  there  will  be  a  considerable  deposit  of  sodium  palmitate, 
while  the  supernatant  liquor,  containing  mostly  sodium  oleate,  is 
drawn  olf  and  then  decomposed  with  a  concentrated  solution  of  a 
metallic  salt  which,  if  obtainable,  should  contain  no  free  acid  to  pre- 
vent the  formation  of  free  oleo-palmitic  acid.  The  heavy  deposit  of 
oleo-palmitate  so  derived  is  strained  off,  pressed  out  in  the  strainer 
and  the  adherent  water  evaporated  in  a  water-bath ;  after  this  it  is 
dissolved  in  about  six  to  eight  times  its  quantity  of  petroleum  benzin 
and  the  insoluble  palmitate  is  left  to  subside  while  the  solution  of 
oleate  decanted  therefrom  is  filtered  off.  The  benzin  evaporated  will 
yield  an  oleate  that  is  entitled  to  that  name,  as  it  is  a  chemical  com- 
bination and  will  remain  stable  and  efficacious. 
The  oleates,  so  prepared,  present  an  amorphous  appearance,  while 
the  palmitates  are  of  a  crystalline  character.  While  I  have  noticed  a 
marked  affinity  of  some  of  the  metallic  salts  for  palmitic  acid,  the 
absence  of  it  in  others  is  remarkable.  Thus,  mercury,  zinc,  bismuth 
and  lead  combine  with  palmitic  acid  abundantly,  but  iron  and 
copper  seem  to  form  an  exception  herefrom,  and  while  the  oleates  of 
mercury,  iron  and  copper  seem  to  be  desirable  as  therapeutic  agents, 
the  oleo-palmitates  of  zinc,  bismuth  and  lead  appear  preferable.  To 
take  up  each  one  of  the  above-named  alone,  I  would  state  that  the 
oleo-palmitate  of  zinc  is  a  pulverulent  substance,  imparting  a  greasy 
touch,  not  unlike  that  of  powdered  soapstone,  and  will  readily  dissolve 
in  warm  oils,  cosmolin,  etc.,  imparting  to  them  a  semi-diaphanous 
appearance  on  cooling.  One  part  dissolved  in  five  of  cosmolin 
makes  an  ointment  of  zinc  oleate,  of  which  I  have  heard  much 
praise  in  eczema  and  other  dermic  affections.  Applied  dry  to  excori- 
ated and  erythematous  surfaces  it  acts  mechanically  by  relieving  fric- 
tion, and  by  its  astringent  properties  it  helps  to  correct  and  heal  the 
parts.  It  is  prepared  by  precipitating  the  soap  solution  with  zinc 
sulphate. 
