150 
ON  DECOLORIZING-  CHARCOALS. 
horse-hair  furnish  ashes  containing  all  the  substances  which  have 
just  been  mentioned. 
The  ashes  of  the  horns  of  the  ox  and  the  buffalo,  those  of  the 
hoof  of  the  ox  and  the  roebuck,  as  well  as  the  hoof  of  the  elk, 
were  rich  in  sulphates  of  lime  and  magnesia ;  there  was  also 
silica  and  traces  of  phosphate  ;  there  was  neither  chlorine  nor 
iron  ;  the  ashes  of  hair  and  fur  always  contained  carbonic  acid  ; 
the  ashes  of  horns  and  hoofs  above  mentioned  were  quite  free 
from  it. 
The  fatty  bodies  extracted  from  hair  are  for  the  most  part 
composed  of  oleine,  margarine  and  margaric  acid.  M.  Van  Laer 
had  already  arrived  at  an  identical  result ;  however,  M.  Yon 
Bibra  found,  only  once,  it  is  true,  cerebric  acid,  or  at  least  an 
analogous  matter ;  this  was  with  woman's  hair,  which  had  fallen 
off  spontaneously ;  this  acid  was,  indeed,  insoluble  in  cold  ether, 
and,  moreover,  it  contained  nitrogen. — Chemist,  Sept.  1856, 
from  Annalen  der  Ohemie  und  Pharmacie. 
ON    DECOLORIZING  CHARCOALS,  AND    THEIR    POWER  OF 
ABSORBING  SOME  OF  THE  GASES. 
By  John  Stenhouse,  LL.D.,  F.  R.  S. 
The  singular  property  which  vegetable  charcoal  possesses  of 
removing  odors  and  colorizing  matters  from  solutions,  was  first 
observed  by  Lowitz  towards  the  close  of  the  last  century.  In 
1811,  Professor  Figuier,  of  Montpellier,  ascertained  that  animal 
charcoal  or  bone-black,  as  it  is  called,  was  immensely  more  effi- 
cacious as  a  decolorizer  than  any  of  the  ordinary  kinds  of 
vegetable  charcoal.  M.  Figuier's  discovery  was  speedily  con- 
firmed by  numerous  other  experimenters,  and  soon  afterwards 
applied  to  the  refining  of  sugar,  for  which  bone-black  has  ever 
since  formed  one  of  the  most  important  reagents. 
The  way,  however,  in  which  charcoal  acts  as  a  decolorizer, 
remained  involved  in  considerable  obscurity  till  1822,  when  three 
prize  essays  on  the  subject  were  published  by  MM.  Bussy,  Payen, 
and  Desfosses.  M.  Bussy's  memoir  was  particularly  valuable, 
and  threw  much  light  on  the  subject.  Those  of  Payen  and 
Desfosses,  though  less  systematic  and  practical  than  M.  Bussy's 
memoir,  agreed  with  it  in  its  general  conclusions.    These  were 
