CRYSTALLINE  DEPOSIT  FROM  OIL  OF  BITTER  ALMONDS.  267 
manganese  is  added  to  the  oil,  the  brown  coloration  of  the  oil 
remains. 
Two  organic  acids  afforded  us,  with  the  protoxide  of  cobalt 
and  manganese,  salts  analogous  to  that  of  the  borate,  namely, 
benzoic  and  hippuric  acids.  The  resulting  resins  behave  them- 
selves as  weak  acids. 
The  rapid  action  of  the  borate  of  manganese,  and  the  colora- 
tion which  it  communicates  to  the  film,  do  not  produce  any  bad 
results  if,  in  its  preparation,  a  certain  quantity  of  some  service- 
able substance  is  mixed  with  the  paint.  This  completely  obviates 
this  disadvantage,  and  renders  the  drying  material  not  injurious. 
Annals  of  Pharmacy,  from  Moniteur  Industrie!. 
EXAMINATION  OF  THE  CRYSTALLINE  DEPOSIT  WHICH  FORMS  IN 
OIL  OF  BITTER  ALMONDS. 
By  John  Stenhouse,  LL.D.,  F.  R.  S. 
When  oil  of  bitter  almonds  is  kept  for  some  time  in  loosely- 
stoppered  bottles,  a  crystalline  deposit  not  unfrequently  forms  in 
it,  especially  if  the  oil  is  exposed  to  the  influence  of  the  light.  So 
long  ago  as  1823,  M.  Stange  declared  this  crystalline  deposit  to 
be  simply  benzoic  acid  produced  by  the  oxidation  of  the  oil,  a 
statement  which  was  confirmed  in  1830  by  Robiquet  and  Boutron- 
Challard.  (Ann,  de  Chim.  et  de  PJiys.,  vol.  xliv.,  p.  364.)  It 
does  not  appear,  however,  that  any  of  these  chemists  subjected 
the  supposed  benzoic  acid  to  the  test  of  analysis.  Subsequently 
the  late  Dr.  Jonathan  Pereira,  in  the  first  edition  of  his  Elements 
of  Materia  Medica,  p.  1107,  stated  that  he  had  met  with  «  three 
kinds  of  a  crystalline  substance  from  oil  of  bitter  almonds,  differ- 
ing essentially  from  each  other  and  from  benzo:'c  acid."  These 
deposits  were  examined  by  Dr.  Pereira,  and  one  of  them,  that 
marked  No,  3,  by  Dr.  Letheby.  None  of  them  were  subjected 
to  analysis,  but  they  were  tested  by  the  action  upon  them  of  oil 
of  vitriol,  caustic  potassa,  &c.  These  crystalline  deposits  were 
given  to  Dr.  Pereira  by  Mr.  George  Whipple,  who  kindly  fur- 
nished me  a  few  weeks  ago  with  no  fewer  than  ten  different  speci- 
mens of  a  similar  character  which  had  formed  in  as  many  por- 
tions of  oil  of  bitter  almonds.  The  weight  of  the  crystals  exceeded 
three  ounces. 
