56  Practical  Notes  from  Forek/n  Journals.     { "^"'/eiriS* 
1880,  p.  138-142,  and  has  been  corroborated  l)y  Prof.  Remington, 
who  states  that  the  addition  of  some  properly  made  mercurial  oint- 
ment which  is  entirely  free  from  rancidity,  facilitates  the  extinction  of 
the  mercury'^  (^^Am.  Jour.  Phar.,'^  1881^  p.  192). 
That  ether  is  an  excellent  aid  in  the  extinguishment  of  mercury  was 
noticed  by  J.  L.  Desmarest  in  1829,  and  Eugene  Renoult  recom- 
mended the  use  of  30  grams  of  it  for  one  kilogram  of  lard  ("I'Officine'') ; 
its  employment  in  conjunction  with  mercurial  ointment /ro>/i  a  previous 
operation  (it  will  be  noticed  that  old  ointment  is  not  mentioned)  was 
strongly  recommended  by  Geo.  Bayle  in  1874  ("Am.  Jour.  Phar.," 
1874,  p.  561).  The  ether  will  evaporate  during  the  trituration,  and 
the  remaining  ointment  will  then  be  as  prone  to  rancidity  as  without 
its  addition.  It  would  therefore  seem  to  be  advisable  to  add  a  pre- 
servative agent,  for  which  purpose  at  various  times,  storax,  Peruvian, 
balsam,  tincture  of  tolu,  tincture  of  benzoin,  and  benzoinated  lard  have 
been  proposed.  Prof.  Remington  advocates  compound  tincture  of 
benzoin  in  a  proportion  which  would  introduce  less  than  one  per  cent, 
of  resinous  matter  into  the  ointment,  an  amount  which  appears  to  be 
too  insignificant  for  causing  irritation.  But  it  seems  to  be  well  worthy 
of  investigation,  whether,  by  substituting  cacao  butter  or  a  similar  fat 
for  the  suet,  a  permanently  sweet  and  non-irritating  ointment  cannot 
be  produced.  The  addition  of  paraffin  to  the  lard  does  not  prevent 
the  latter  from  turning  rancid,  and  the  substitution  of  soft  paraffin 
for  all  the  fats  is  objectionable  on  therapeutic  grounds,  at  least  in  a 
number  of  cases. 
PRACTICAL  NOTES  FROM  FOREIGN  JOURNALS. 
By  the  Editor. 
Testing  of  Benzoic  Acid. — The  asserted  reduction  of  potassium  per- 
manganate by  benzoic  acid  prepared  from  urine  has  been  the  subject 
of  several  investigations.  Dr.  C.  Schacht  ("Archiv  d.  Ph.,'^  Nov.,  1881, 
p.  321)  has  made  comparative  experiments  with  benzoic  acid  obtained 
1,  from  urine;  2,  from  toluol;  3,  from  benzoin  (commercial);  4,  from 
Siam  benzoin  by  sublimation;  5,  from  the  same  by  the  wet  process. 
In  acid  and,  more  characteristically,  in  alkaline  solution,  a  reduction 
takes  place  only  with  the  last  two  acids.  On  dissolving  at  15°C.  O'l 
gram  of  benzoic  acid  in  3  cc.  of  potassa  solution,  spec.  gr.  1*177,  diluting 
with  3  cc.  of  distilled  water,  adding  5  drops  of  a  |^  per  cent,  solution 
