546       NEW  FALSIFICATION  OF  OIL  OF  BITTER  ALMONDS. 
potassa  and  expel  most  of  the  alcohol,  until  about  one-third  of 
the  original  measure  is  left,  when  it  is  set  aside  to  cool.  In 
several  experiments  made  with  pure  oil  in  the  above  manner,  the 
residue  was  a  liquid  of  a  brownish  yellow  color,  without  any  sign 
of  crystallization,  and  was  wholly  soluble  in  water,  with  but  a 
very  slight  turbidity.  The  adulterated  oil  above  referred  to,  on 
cooling,  became  a  hard  crystalline  mass  of  a  dark  brown  color, 
while  a  little  caustic  potassa  remained  in  solution,  free  of  color, 
below  the  crystals.  The  whole  residue,  when  agitated  with  water, 
furnished  a  very  turbid  liquid,  from  which  a  large  quantity  of  a 
yellowish  brown  sediment  had  separated  in  the  course  of  a  few 
hours  ;  the  supernatant  liquor  remained  turbid  after  a  week. 
A  small  quantity  of  the  adulterated  oil  mixed  with  the  pure 
article  furnished,  after  the  above  treatment,  an  aqueous  solution, 
which;  on  standing  a  few  hours,  became  clear,  and  deposited  a 
yellow  crystalline  powder.  With  the  proportional  increase  of 
nitrobenzole  in  pure  oil  of  bitter  almonds,  the  last  solution  re- 
tained its  turbidity  for  a  longer  time,  and  the  crystalline  sedi- 
ment increased  in  bulk, 
The  above  test  takes  but  a  few  minutes  to  perform,  and  the 
cost  is  a  mere  trifle  ;  the  operation  is  very  simple,  it  does  not 
require  any  apparatus,  and  may  be  made  over  a  spirit  lamp  or  in 
a  water  bath. 
In  connection  with  this,  I  would  state  that  I  have  often  found 
otherwise  pure  oil  of  bitter  almonds  adulterated  with  alcohol. 
The  easiest  way  to  detect  the  same  is  Redwood's  method,  by 
means  of  nitric  acid  ;  pure  oil  dissolves  in  this  liquid  at  ordinary 
temperature  without  decomposition  ;  a  small  quantity  of  alcohol, 
however,  if  present,  is  acted  on  by  the  nitric  acid  with  the  evolu- 
tion of  nitrous  acid  fumes.  Nitrobenzole  is  likewise  soluble  in 
cold  nitric  acid  without  undergoing  any  change  even  on  heating. 
The  nitric  acid  test  therefore  ought  not  to  exclude  the  potassa 
test,  to  be  satisfied  about  the  purity  of  the  oil.  How  small  a 
quantity,  however,  o£  nitrobenzole  may  be  detected  by  means  of 
caustic  potassa,  and  how  the  per  centage  of  such  an  adulteration 
may  be  readily  found  out,  I  am  at  present  not  prepared  to  say : 
future  experiments,  however,  I  hope,  may  determine  these  facts. 
Philadelphia,  Sept.,  1857. 
