^"^M^Z'^ln-"  '}   Preparation  of  Mercurial  Ointment,  141 
mercury  to  the  presence  of  fatty  acids,  somebody  suggested  to  add  a 
few  drops  of  olein  to  the  fatty  matter  used  for  triturating.  The  mass 
turns  foamy  when  triturated  without  mixing  with  the  mercury. 
20.  Donovan  thinks  that  the  metal  is  first  transformed  into  mercu- 
rous  oxide  before  it  dissolves  in  the  fat ;  that  it  is  only  efficacious  in 
solution,  and  that  the  balance  of  the  metal  is  wasted  and  useless  ;  in 
order  to  obtain  an  ointment  containing  no  free  metal,  the  oxide  is  to  be 
digested  with  the  fat  for  some  time  at  150  to  160°  ;  the  mixture  is 
then  cooled  and  triturated.    I  did  not  try  this  suggestion. 
21.  GodefFroy  uses  vaseline  instead  of  the  old  ointment,  and  claims 
to  obtain  a  perfect  ointment  in  a  shorter  time.  I  tried  the  plan  on  a 
large  scale,  and  obtained  in  two  minutes  a  uniform  grayish-white  mix- 
ture, containing  numerous  metallic  globules  ;  the  mercury  was  extin- 
guished to  an  equal  extent  in  two  minutes  as  it  was  when  triturated 
with  old  ointment  for  10  to  15  minutes.  I  then  supposed  vaseline  to 
be  the  best  vehicle,  but  soon  became  aware  of  my  mistake,  since 
further  trituration  for  eight  days  produced  no  noticeable  change  in  the 
ointment,  the  mercury  being  apparently  no  more  extinguished  than  it 
was  at  the  end  of  the  first  two  minutes.  I  therefore  suppose  that 
GodefFroy  commenced  the  trituration  with  the  pestle,  and  continued  it 
with  pen  and  ink. 
22.  Lautenschlaeger  conducts  ozone  into  melted  lard,  and  extin- 
guishes the  mercury  with  the  ozonized  lard  in  a  remarkably  short  time, 
I  see  no  particular  gain  of  time  in  this  process,  and  prefer  old  ointment 
as  a  vehicle. 
23.  Kenzel  made  a  celebrated  blue  ointment  in  the  eighteenth  cen- 
tury by  adding  6  grains  of  sulphur  to  2  ounces  of  the  lard  ;  thus  a  very 
efficacious  ointment  is  obtained  in  a  short  time. 
24.  Hager  suggests  either  old  ointment  or  a  mixture  of  i  part  of 
wax,  I  part  of  tallow,  and  3  parts  of  olive  oil.  The  latter  mixture  is 
far  inferior  to  old  ointment,  and  will  only  prove  successful  in  connec- 
tion with  absolute  alcohol. 
Attempts  to  prepare  an  ointment  with  lard,  to  which  an  alcoholic  or 
an  aqueous  potassa  solution  had  been  added,  yielded  unsatisfactory 
results. 
In  almost  all  these  experiments  I  used  steam-power,  and  feel  fully 
convinced  by  the  results  that 
I.  The  best  vehicle  for  extinguishing  the  mercury  is  not  "old  ran- 
