68  Ointments  of  Oxide  of  Zinc,  etc.  {AVelvi,m£*' 
This  observation  at  once  suggested  the  probability  that  the  spirit 
used  for  these  experiments  contained  acetic  acid,  which  was  proven 
byj;he  deep  red  color  produced  with  it  after  neutralization  with  am- 
monia, by  a  ferric  salt,  the  color  disappearing  on  the  addition  of  acids. 
Spirit  of  nitrous  ether,  however,  which  had  been  recently  prepared 
by  Redwood's  process,  was  entirely  free  from  acetic  acid  and  did  not 
produce  the  red  color  with  salts  of  iron. 
It  is  well  known  that  by  the  action  of  nitric  acid  upon  alcohol, 
nitrous,  acetic  and  formic  ethers  are  formed,  in  variable  proportions, 
depending  chiefly  on  the  strength  of  the  materials  employed,  and  on 
the  temperature  at  which  the  distillation  took  place.  The  two  last- 
named  ethers  do  not  affect  the  color  of  ferric  chloride  until  by  expo- 
sure or  by  the  action  of  caustic  alkalies  acetic  and  formic  acids  have 
been  liberated  from  their  ethylic  combination,  when,  after  neutraliza- 
tion, the  peculiar  red  color  will  appear  with  ferric  chloride,  more  or 
less  modified  by  the  smaller  or  larger  excess  of  the  iron  salt,  or  by 
the  presence  of  a  compound  striking  with  it  a  peculiar  color. 
Old  spirit  of  nitrous  ether  contains  also  free  nitrous  or  nitric  acid, 
as  may  be  seen  by  the  blackish-brown  color  produced  with  ferrous 
salts  on  the  addition  of  hydrochloric  or  sulphuric  acid. 
OINTMENTS  OF  OXIDE  OF  ZINC,»AND  OF  MERCURY. 
By  Julius  Kalish. 
Ungt.  Zinci  Oxidi. — In  the  last  number  of  the  "  American  Jour- 
nal of  Pharmacy,"  a  process  is  given  by  Mr.  Bolton,  which,  while  it 
will  give  a  very  smooth  ointment,  is  too  expensive,  requiring  too 
much  time  and  labor  in  its  execution.  It  consists  essentially  of  grind- 
ing the  oxide  in  the  fat. 
I  have  prepared  this  ointment  in  the  following  way,  which  accom- 
plishes the  same  results  by  far  less  labor,  the  great  desideratum  in  all 
formulas : 
Rub  the  zinc  oxide  in  a  wedgwood  or  unglazed  porcelain  mortar, 
with  considerable  pressure,  until  as  finely  divided  as  possible ;  now 
add  gradually,  with  constant  trituration  and  pressure,  sufficient  sweet 
oil  of  almonds  to  form  a  smooth  paste ;  then  add  a  little  lard,  mix 
thoroughly  ;  then  add  balance. 
This  process  will  answer  for  all  ointments  containing  insoluble  sub- 
stances, and  for  all  ordinary  quantities.  I  have  always  succeeded 
with  it  in  making  smooth,  uniform  ointments. 
