138       NOTE  ON  VARIOUS  PHENOMENA  OF  OXYGENATION. 
their  colors  by  contact  with  the  aerated  essential  oil.  The  essen- 
tial oil,  freshly  distilled,  possesses  no  oxidizing  power. 
In  the  association  of  colors  applicable  to  painting  in  oil,  regard 
must  therefore  be  had  not  only  to  the  modifications  which  may 
be  produced  upon  certain  colors  by  the  various  mutual  reactions 
of  the  coloring  matters,  but  also  to  the  oxidizing  action  of  the 
essential  oil,  which  must  be  manifested  at  the  first  moment  of  its 
application  in  the  form  of  varnish. 
General  Considerations. 
In  all  the  reactions  just  referred  to,  the  oil  of  turpentine,  and 
in  general  the  essences  which  are  capable  of  absorbing  oxygen 
from  the  air,  behave  as  oxidants,  the  energy  of  which  is  suffi- 
ciently marked  by  the  great  elevation  of  temperature  produced  by 
the  contact  of  the  aerated  essential  oil  with  a  solution  of  sul- 
phurous acid. 
It  is  important  to  ascertain  whether  this  oxidizing  property 
belongs  to  certain  oils,  and  whether  the  proof  of  this  fact  may 
not  account  for  the  frequent  spontaneous  combustion  of  oiled 
tissues.  Considerable  interest  also  attaches  to  the  investigation 
of  the  action  of  the  vapors  of  essential  oils  upon  putrid  miasmata, 
and  the  determination  of  th^  question  whether,  in  these  cases, 
there  is  not  a  combustion  of  the  principles  diffused  in  the  air. 
If  oxygen  can  thus  dissolve  in  certain  liquids  without  combin- 
ing, we  are  led  to  suppose  that  where  it  is  disengaged  it  exerts 
its  action  upon  the  bodies  with  which  it  is  in  contact  in  the  dis- 
solved state  before  becoming  gaseous.  Are  not  the  same  cir- 
cumstances presented  in  all  the  chemical  reactions  in  which  in 
our  explanations  we  have  recourse  to  the  intervention  of  nascent 
gases  ? 
Thus  we  shall  be  led  to  imquire  whether  other  bodies  do  not 
share  with  certain  essences  in  the  power  of  forming  a  provision 
of  oxygen,  and  yielding  this  reagent  to  assist  in  various  reac- 
tions. This  study  may  throw  great  light  upon  the  phenomena 
of  animal  and  vegetable  physiology.  The  solution  of  oxygen  in 
the  blood  by  the  act  of  respiration,  and  its  subsequent  assimila- 
tion, already  present  a  great  analogy  to  the  phenomena  which 
have  just  been  described.  As  a  question  of  health,  it  would  be 
advisable  to  ascertain  what  may  be  the  consequences  of  the  re- 
