562 
Adulteration  of  Food. 
S  Am.  Jour.  Pharm. 
t    Dec.  1. 1871. 
cells  in  the  outer  skin,  and  the  hard  angular  ones  of  the  inner  part 
of  the  seed. 
Many  examples  of  the  above  and  other  kinds  of  adulteration,  mounted 
for  the  microscope,  were  exhibited  at  the  same  time,  for  comparison 
with  pure  specimens. — Lond.  Chem,  News^  October  27,  1871. 
SOLVENTS  FOR  INDIGO. 
Dr.  B.  Jacobsen. 
Translated  by  C.  Dengenhardt. 
Some  new  solvents  for  indigo  have  lately  been  given  by  de  Aguiar 
and  Baeyer,  and  by  Prof.  Wartha.  (See  American  Chemist^  Vol.  I, 
p.  '472).  To  these  I  will  also  add  a  few  which  I  have  discovered. 
That  aniline  will  dissolve  indigo  has  been  known  several  years,  from 
my  own  experiments.  But  an  equally  good  solvent  for  indigo  is  nitro- 
benzol,  which  when  heated  with  indigo  is  colored  a  deep  violet  blue, 
and  on  cooling  deposits  flaky  crystals  and  then  appears  dark  red, 
probably  from  red  indigo. 
In  greater  or  less  quantities  the  following  smbstances  dissolve  in- 
digo at  their  boiling  points  : 
Castor  oil,  acetone,  hydrate  of  chloral,  camphor,  oil  of  turpentine, 
balsam  of  copaiba,  cedar  oil  (oil  of  Juniper  virgin),  amylic  alcohol, 
oil  of  lavender,  white  beeswax,  Japanese  vegetable  wax  and  Carnauba 
wax,  (from  this  last  small  flaky  crystals  precipitate). 
The  higher  the  boiling  point  of  the  solvent,  the  redder  is  the  appear- 
ance of  the  solution,  so  that  bodies  like  acetone,  amylic  alcohol  and 
hydrate  of  chloral  give  a  clear  blue.  Castor  oil,  cedar  oil,  etc.,  a 
violet  blue,  and  the  different  kinds  of  wax  a  purple  red  solution.  If 
kept  for  a  short  time  at  the  boiling  point  with  white  wax,  the  color 
changes  from  scarlet  to  orange,  and  at  last  to  a  brown.  The  indigo 
is  reduced  by  the  formation  of  acrolein,  and  the  solution  retains  its 
brown  color  even  on  the  addition  of  gasoline. 
If  powdered  indigo  is  added  to  melting  picric  acid,  the  former  will 
be  decomposed  with  deflagration. 
