T6 
ON  THE  ODORS  CP  PERFUMES. 
dextrine,  which  is  not  reprecipitated  by  water.  Fibrose  sub- 
mitted to  the  action  of  strong  sulphuric  acid,  dissolves  like  cellu- 
lose, but,  on  immediately  adding  water  to  the  acid  solution,  it  is 
reprecipitated  in  the  form  of  a  thick  transparent  jelly. — Lon- 
Pharm.  Jour.  Oct,  1859. 
ON  THE  ODORS  OF  PERFUMES. 
On  occasion  of  the  discussion  which  we  have  just  recorded, 
M.  Chevreul  offered  his  ideas  upon  the  mode  of  action  of  odori- 
ferous substances.  This  discussion  was  intended  to  recall  the 
publications  which  this  distinguished  chemist  has  made  during 
the  past  thirty  years — researches  made  specially  to  trace  odors 
to  their  material  causes.  He  reviews  in  the  following  manner 
the  action  by  which  bodies  exert  their  odors  when  properly 
mixed  with  other  odoriferous  materials.  1st.  Bodies  themselves 
odorant  disguise  the  odors  of  other  substances,  as  a  strong  light 
overpowers  a  feeble  one.  2d.  Bodie3  being  themselves  odori- 
ferous act  in  the  manner  of  an  acid  in  neutralizing  a  base.  3d. 
Solid  bodies  may  act  by  capillary  affinity  to  absorb  odors,  as  is 
the  case  for  example  with  charcoal.  4th.  Other  bodies  act  by 
altering  the  constitution  of  the  odorant  substance,  producing 
new  compounds  either  odorless  or  nearly  so.  Such  is  the  ac- 
tion of  moist  chlorine  or  oxygenated  water.  5th.  Lastly,  the 
action  may  be  two-fold,  as  in  the  case  of  chlorine  and  ammonia, 
decomposing  one  portion  and  neutralizing  the  other  without 
decomposition. 
Neutralization  includes  the  largest  class  of  cases  ;  thus  the 
volatile  odorous  acids  are  neutralized  by  alkalies  to  form  odor- 
less salts.  Ammonia  loses  its  odor  when  united  to  an  acid.  The 
odors  in  such  cases  are  truly  neutralized,  since  displacing  the 
acids  liberates  again  the  odors  each  in  its  own  character.  Ex- 
amples of  the  destruction  of  odors  are  numerous  and  well  known 
to  chemists.  Sulphydric  acid,  for  instance,  is  at  once  decom- 
posed by  chlorine  and  consequently  disinfected.  Ammonia  by 
the  action  of  chlorine  offers  an  example  of  both  neutralization  and 
destruction  of  odors,  because  at  the  same  time  we  have  decom- 
position of  one  part  of  the  base  and  the  neutralization  of  another 
part  by  the  chlorohydric  acid  formed. 
