400  DECOLORIZING  PROPERTY  OF  THE  ESSENTIAL  OILS. 
An02  S03,  and  remained  so ;  other  oils  remained  perfectly  trans- 
parent from  the  beginning. 
It  will  be  perceived  that  both  classes  of  oils,  those  containing  no 
oxygen  and  those  into  which  that  element  enters  as  a  constituent, 
are  enumerated  among  the  bleaching  agents.  As  commercial  oil 
of  turpentine  is  more  or  less  oxygenated,  I  attempted  to  introduce 
pure  camphene  into  the  blue  solution.  Into  a  small  retort  I  poured 
about  half  a  drachm  of  very  limpid  spirits  of  turpentine,  with 
twenty  or  more  times  the  quantity  of  distilled  water.  The  retort 
was  then  exposed  to  the  vapor  of  boiling  water  in  one  of  the  small 
holes  of  the  Beindorf's  apparatus,  and  the  neck  introduced  into  a 
test-tube  containing  the  blue  liquid,  so  far  as  to  close  the  mouth  of 
the  tube.  The  extremity  of  the  neck  of  the  retort  scarcely  reached 
the  surface  of  the  blue  liquid.  In  a  few  minutes,  without  any  per- 
ceptible distillation,  the  blue  liquid  became  as  colorless  as  water, 
the  vapor  of  camphene  having  apparently  been  absorbed  by  the 
fluid  in  the  test-tube.  Citrene,  obtained  in  like  manner,  acted  as 
the  camphene  did. 
Balsam  of  copaiva,  without  heat,  changed  the  color  of  its  own 
bulk  of  sulphindigotic  acid  in  solution  to  a  mere  shade  of  greenish 
blue.  The  active  principle  in  this  case  was  probably  the  volatile 
oil  of  copaiva. 
A  drying  oil  was  now  tried.  Linseed  oil  in  the  proportion  of 
about  eight  parts  to  one  of  An02+S03,  caused  the  blue  color  to 
abate,  and  by  agitation  and  heat  the  depth  of  color  was  still  fur- 
ther diminished,  but  the  blue  tinge  was  not  wholly  dissipated  until 
the  next  day,  when  every  vestige  of  color  was  removed.  The  oil 
appeared  like  yolk  of  egg. 
Glycerine  (a  few  drops  to  the  test-tube  one-third  full)  instant- 
ly disappeared  in  the  blue  solution,  and  reduced  it  to  a  very  pale 
greenish-blue  color. 
Camphor,  boiled  several  minutes  in  the  indigo  solution,  made  no 
perceptible  change  in  its  color. 
Tincture  of  camphor,  shaken  with  the  blue  liquid,  converted  the 
blue  to  a  greenish  hue.  The  blue  liquid  diluted  to  the  same  ex- 
tent by  water  or  alcohol  retained  its  blue  tint.  After  two  days 
standing  without  change,  both  camphorated  mixtures  were  placed 
a  few  hours  in  the  sun:  the  result  was,  the  liquid  in  both  tubes 
became  completely  bleached. 
