594 
Oleates. 
Am.  Jour.  Pharm. 
Dec,  1889. 
The  oleates  which  have  withstood  the  test  of  therapeutical  experi- 
ments and  are  still  prescribed  are  the  oleates  of  zinc,  mercury,  copper, 
lead  and  bismuth,  and  the  alkaloidal  solutions  the  so-called  oleates  of 
aconitine,  cocaine,  morphine,  veratrine  and  quinine. 
It  is  not  the  object  of  the  present  communication  to  present  an 
entirely  original  line  of  thought,  but  to  record  a  few  observations  on 
this  subject  and  to  furnish  working  formulas  for  those  oleates  which 
the  pharmacist  is  called  upon  to  dispense,  and  which  will  undoubtedly 
claim  the  attention  of  the  Committee  of  Revision  of  the  Pharmacopoeia 
in  1890,  and  to  call  particular  attention  to  a  few  points  in  manipula- 
tion which  are  essential  to  note  in  order  to  obtain  good  products. 
First,  it  is  to  be  observed  that  the  character  of  the  product  is 
materially  altered  by  the  concentration  of  the  solutions  used  and  the 
temperature  at  which  the  precipitation  is  accomplished.  The  same 
strength  of  solutions  will  not  answer  for  all  of  the  oleates,  nor  can  a 
uniform  temperature  be  adopted  for  their  precipitation. 
Secondly,  neutral  solutions  or  only  slightly  acid  solutions  of  the 
metallic  salts  can  be  used,  a  strongly  acid  solution  decomposing  the 
oleate  of  potassium  or  sodium  used,  with  the  liberation  of  oleic  acid. 
On  the  other  hand,  an  alkaline  oleate  solution  will  yield  a  product 
more  or  less  contaminated  with  a  hydrate  of  the  base. 
It  was  proposed  by  Dr.  J.  V.  Shoemaker  {loo.  eit.)  and  also  by  H. 
B.  Parsons  (loc.  cit.)  to  use  a  solution  of  Castile  soap  as  a  precipitant. 
The  Castile  soap  of  the  market  is  of  questionable  composition,  varying 
considerably  and  usually  yields  a  solution  with  water  which  clears  or 
subsides  but  slowly,  and  is  filtered  with  difficulty.  It  seems,  there- 
fore, to  me  advisable  to  replace  this  with  a  solution  of  oleate  of  potas- 
sium or  sodium  prepared  by  saponification  of  oleic  acid  with  an 
alkali. 
The  preparation  of  a  neutral  soap  with  an  aqueous  solution  of  alkali 
is  difficult,  the  attempt  resulting  in  a  decidedly  alkaline  solution.  If 
an  acid  oleate  of  the  alkali  is  produced  it  will  produce  a  cloudy  solu- 
tion which  will  not  filter  readily  (the  acid  oleates  of  the  alkalies  being 
insoluble).  For  these  reasons  hydro-alcoholic  solutions  of  the  alkaline 
hydrate  are  used,  by  which  means  a  perfectly  neutral  soap  can  be  pro- 
cured, which  can  be  easily  diluted  with  water  and  the  solution  filters 
easily  through  paper.  Experiments  showed  that  the  quantity  of  alco- 
hol necessary  can,  with  proper  manipulation,  be  reduced  to  compara- 
tively a  small  amount. 
