444 
ORGANIC  MATTER  OF  THE  AIR. 
fluid-drachms,  and  having  mixed  this  with  the  portion  first  ob- 
tained, add  the  oil  of  rose  and  mix  the  fluid  extract  thus  made 
with  the  clarified  honej. 
As  thus  prepared  Honey  of  Roses  is  highly  astringent,  and 
possesses  much  richness  of  color  and  flavor. — Journ.  Trans.  Md. 
Col.  PI i arm.,  June,  1859. 
ON  THE  ESTIMATION  OF  THE  ORGANIC  MATTER  OF  THE 
AIR. 
By  Robert  Angus  Smith,  Esq.,  Ph.  D.,  F.  R.  S. 
After  describing  the  opinions  concerning  organic  matter  in 
the  air,  and  the  various  attempts  made  to  estimate  the  amount, 
the  lecturer  described  a  method  of  obtaining  the  relative  quan- 
tity by  means  of  mineral  chameleon,  permanganate  of  potash  or 
soda.  This  mineral  had  been  proposed  by  Forchammer  as  a  mode 
of  estimating  the  organic  matter  in  water,  but  it  was  capable  of 
estimating  quantities  much  more  minute.  At  first  the  air  was 
passed  through  the  solution  of  chameleon,  but  this  was  not  found 
to  cause  complete  action.  It  was  necessary  that  the  air  should 
remain  for  some  time  in  contact  with  the  solution  to  be  decom- 
posed. It  was  then  ascertained  that  the  relative  amount  of  or- 
ganic and  other  oxidizable  matter  in  air  could  be  found  by  a 
simple  metrical  experiment  in  a  few  minutes. 
The  lecturer  then  said  : — In  working  out  this  idea,  it  has  been 
found  that  a  vessel  of  the  capacity  of  80  to  100  cubic  inches  is 
the  most  convenient.  This  is  equal  to  rather  less  than  a  quart 
and  a  half,  [Imp.  mea.]  and  rather  more  than  a  litre  and  a  half. 
The  solution  of  chameleon  used  must  be  extremely  weak,  so 
that  small  quantities  cannot  readily  be  distinguished  by  gaslight. 
600  grains  of  it  are  required  to  decompose  5  grains  of  a  standard 
solution  of  oxalic  acid.  The  standard  solution  of  oxalic  acid  is 
so  made  that  1000  grains  neutralize  1  grain  of  carbonate  of 
soda.  A  thousand  grains  contain  therefore  1-184  grain  of  crys- 
tallized oxalic  acid. 
To  prepare  the  solution,  a  manganate  was  formed  by  heating 
nitrate  and  carbonate  of  soda  and  manganese,  assisted  by  a  little 
chlorate  of  potash.    There  was  the  most  minute  trace  of  nitrate 
