356 
DISINFECTING  PROPERTIES  OF  CHARCOAL. 
benzoic  acid,  and  no  wonder,  under  such  circumstances,  that  the 
public  preferred  the  preparations  they  had  been  accustomed  to, 
which  were  not  so  liable  to  change.  He  (Mr.  R.)  considered 
that  the  great  desideratum  at  present  was  to  give  the  purified 
oil  (the  hyduret  of  benzoyle)  a  degree  of  permanence  equal  to 
that  of  the  crude  or  unpurified  oil — Transactions  of  the  Pharm- 
aceutical Society,  April  5th,  1854. 
ON  THE  DEODORIZING  AND  DISINFECTING  PROPERTIES 1  OF 
CHARCOAL,  WITH    THE    DESCRIPTION    OF   A  CHARCOAL 
RESPIRATOR  FOR  PURIFYING  THE  AIR  BY  FILTRATION. 
By  John  Stenhouse,  LL.D.,  F.R.S. 
The  powerful  effects  of  freshly-burned  wood-charcoal,  espe- 
cially when  coarsely  powdered,  in  absorbing  gases  and  vapors, 
have  been  long  known.    Hence  the  limited  extent  to  which 
charcoal  has  been  occasionally  employed  to  sweeten  foetid  water 
and  animal  substances  in  the  incipient  stages  of  putrefaction. 
Sufficient  attention  has  not,  I  think,  however,  been  hitherto  be- 
stowed on  a  second  and  still  more  important  effect  which  charcoal 
exerts  upon  those  complex  products  of  decomposition,  viz.  that 
of  rapidly  oxidizing  them  and  resolving  them  into  the  simplest 
combinations  they  are  capable  of  forming. 
When  coals  or  wood  are  burned  with  an  inadequate  supply  of 
air,  a  variable  amount  of  intermediate  or  secondary  products  is 
generated,  constituting  what  are  called  soot  and  smoke  ;  when, 
on  the  other  hand,  the  combustion  of  the  fuel  is  conducted  with 
an  adequate  supply  of  oxygen  and  a  sufficiently  high  temperature, 
carbonic  acid,  water,  ammonia,  with  perhaps  a  little  nitric  acid, 
are  almost  the  sole  products*. 
The  putrefaction  of  animal  and  vegetable  substances  is  like- 
wise in  general  a  process  of  imperfect  oxidation.  Hence,  under 
ordinary  circumstances,  when  this  is  the  case,  a  variety  of  more 
or  less  complex  secondary  products  is  formed,  which  usually 
possess  very  disagreeable  odors,  and  exert  exceedingly  injurious 
effects  upon  the  animal  economy.  To  these  substances  the 
general  name  of  miasmata  has  been  given.  Not  much  is  known 
of  their  nature  ;  but  they  are  believed  to  be  heavy,  complex, 
nitrogenated  vapors,  which  are  decomposed  by  oxygen,  chlorine, 
sulphurous  acid,  nitric  acid,  and  other  disinfecting  agents. 
