""^  Aut^uYMssT'l      Practmd  Notes  from.  VdiiouH  Sources.  409 
A  PecnHar  Reaction  of  Quinine  HydroGhlorate. — Dr.  Vulpius  ob- 
served that  under  certain  circumstances  a  solution  of  this  salt  is  not 
precipitated  by  nitrate  of  silver.  If,  for  instance^  50  grams  of  a  one 
per  cent,  solution  of  this  salt  be  kept  in  a  rotating  motion,  over  10 
grams  of  silver  nitrate  solution  of  the  same  strength  may  be  added 
drop  by  drop  before  a  precipitation  of  silver  chloride  is  produced.  If, 
however,  a  single  drop  of  the  silver  solution  be  permitted  to  flow  into 
the  test  tube  without  agitation  a  dense  precipitate  is  at  once  pro- 
duced which  by  subsequent  agitation  may  be  finely  divided,  but  does 
not  yield  a  clear  solution.  It  is  possible  that  at  the  moment  of  con- 
tact a  soluble  double  salt  may  be  formed. 
A  solution  of  morphine  hydrochlorate  is  at  once  precipitated  by 
silver  nitrate. — ArcUv  d.  Phar.,  May,  1882,  p.  361. 
Testing  of  Benzoic  Acid. — C.  Schneider  has  modified  Schacht's 
method  (see  this  journal,  February,  p.  56)  of  testing  benzoic  acid,  sub- 
limed from  Siani  benzoin,  by  using  16  (instead  of  5)  drops  of  ^  per 
cent,  solution  of  potassium  permanganate, -which  is  completely  decolor- 
ized and  after  eight  hours  the  liquid  remains  colorless  ("Phar.  Zei- 
tung,'^  No.  20).  The  artificial  benzoic  acids,  or  such  sublimed  with 
Siam  benzoin,  or  prepared  from  benzoin  by  the  wet  process,  do  not 
effect  the  complete  reduction  of  the  test  solution,  and  in  the  presence 
'of  cinnamic  acid  the  odor  of  benzaldehyde  becomes  apparent.  The 
sublimed  acid,  carefully  preserved  in  dark-colored  bottles,  does  not  lose 
this  deoxidizing  power  on  keeping. 
Mr.  Jahns  having  noticed  the  strong  reducing  power  of  vanillin 
upon  permanganate,  experiments  were  also  made  with  this  compound 
.-and  with  mixtures  of  vanillin  and  toluol-benzoic  acid.  Such  mix- 
tures, more  particularly  those  containing  jIq,  ^V?  to  vanillin 
behave  very  similar  to  sublimed  benzoic  acid ;  but,  aside  from  the 
peculiar  odor,  the  liquid,  after  eight  hours,  is  of  a  distinct  yellow  color, 
and  contains  a  deposit  of  colorless  or  slightly  colored  crystals. 
The  author  regards  the  permanganate  test  as  well  adapted  for  dis- 
tinguishing benzoic  acid,  sublimed  from  benzoin,  from  the  acid  of 
other  sources,  and  from  that  which  is  contaminated  with  cinnamic 
acid.  But  he  advocates  its  preparation  by  the  pharmacist. — Archiv  d. 
Phar.,  June,  1882,  pp.  401-403. 
Professor  Ed.  S(^haer  has  likewise  made  a  series  of  com})arative 
experiments  with  benzoic  acid  of  different  origin  and  permanganate. 
