520     DISINFECTING  PROPERTIES  OF  CHARCOAL,  SAND,  ETC. 
It  is  certainly  a  very  important  question  to  be  determined, 
whether,  and  in  what  way,  or  to  what  extent  the  offensive  odor 
of  decomposing  organic  matter  is  connected  with  infection.  We 
agree  with  Dr.  Sutherland  that  the  terms  deodorizer  and  disin- 
fectant ought  not  to  be  commonly  used  in  connexion,  as  if  the 
one  effect  necessarily  followed  the  other.  In  fact,  we  know  very 
little  about  infection,  its  real  nature  and  the  modus  operandi  of 
those  substances  which  have  been  found  or  supposed  to  prevent 
contagion.  It  is  generally  considered  that  the  poison  of  con- 
tagion is  destroyed  by  a  process  of  oxidation,  a  process  similar 
to  that  by  which  offensive  odors  are  usually  got  rid  of.  Admit- 
ting this,  however,  it  does  not  follow  that  the  two  effects  should 
be  necessarily  simultaneous. 
Charcoal  and  lime  are  two  of  the  best  known  substances  for 
preventing  the  escape  of  offensive  odors  from  decomposing  organic 
bodies ;  but  these  two  substances  do  not  act  in  precisely  the  same 
way.  The  action  of  the  charcoal,  in  as  far  as  the  charcoal  itself 
is  concerned,  is  mechanical,  that  is  to  say,  the  charcoal  does  not 
enter  into  chemical  combination  with  any  of  the  elements  pre- 
sent. On  the  other  hand,  the  lime  combines  with  some  of  the 
products  of  decomposition.  But  the  true,  most  active,  and 
efficient  agent  in  destroying  contagion,  is  atmospheric  oxygen. 
Charcoal  possesses  the  property  in  a  very  high  degree  of  con- 
densing gases  upon  its  surface,  and  it  is  thus  capable  of  bringing 
large  quantities  of  atmospheric  oxygen,  in  an  active  state,  into 
contact  with  the  noxious  products  of  organic  decompositions, 
and  causing  their  destruction  by  an  oxidizing  action.  The  ac- 
tion of  sand  or  gravel  would  be  somewhat  similar  to  that  of 
charcoal,  but  with  this  difference,  that  sand  and  gravel  are 
deficient  in  that  property,  which  so  remarkably  distinguishes 
charcoal,  of  condensing  gases  on  their  surface.  The  sand  or 
gravel  acts  simply  as  a  porous  mass,  the  interstices  of  which  are 
filled  with  air,  and  the  gaseous  products  of  decomposition,  on 
passing  through  this  mass,  are  minutely  divided  and  brought  into 
intimate  contact  with  atmospheric  oxygen.  Dr.  Sutherland 
says,  that  a  stratum  of  six  inches  thick  of  sand  placed  over 
ground  filled  with  decomposing  bodies  entirely  deodorized  the 
soil.  In  this  case  we  have  no  doubt  the  action  of  the  sand  was 
such  as  we  have  described. — London  Pharm.  Journ.  Sept.,  1855. 
