Am.  Jour.  Pharm. 
Aug.,  1892. 
Flame  of  Burning  Nitrogen. 
441 
energetic  reduction  of  the  molybdic  compounds.  The  stage  of  the 
blue  oxide  is  overleaped,  and  there  appear  at  once  the  lower 
brownish  stages  of  oxidation.  If  heat  is  applied  and  the  reaction 
is  prolonged,  brownish-black  masses  separate  out  which  are  found 
to  be  a  variable  mixture  of  lower  molybdic  acids,  whilst  a  portion 
of  the  organic  substance  is  oxidized  to  carbonic  acid  and  water. 
But  it  is  not  impossible  that  there  may  appear  simultaneously  yellow 
or  brown  oxidation  products  of  the  oxy-compounds. 
The  sensitiveness  of  these  reactions  is  not  very  great,  but  in  case 
of  pyrocatechin,  pyrogallol,  gallic  acid,  and  tannin,  it  admits  of  the 
recognition  of  01  mgrm.  substance  in  one  cc.  of  liquid.  The 
action  of  sodium  tungstate  is  similar  to  that  of  ammonium  molyb- 
date. —  Chem.  News,  June  24,  1892,  p.  302. 
THE  FLAME  OF  BURNING  NITROGEN. 
By  W.  Crookes,  F.R.S. 
Nitrogen  is  a  combustible  gas  ;  that  is  to  say,  a  mixture  of  nitro- 
gen and  oxygen  (atmospheric  air),  will  under  certain  conditions 
burn  with  a  flame,  and  production  of  nitrous  and  nitric  acids.  The 
reason  why,  when  once  nitrogen  is  set  on  fire,  the  flame  does  not 
spread  throughout  the  whole  atmosphere  and  deluge  the  world  in 
a  sea  of  nitric  acid,  is  that  the  igniting  point  of  nitrogen  is  higher 
than  the  temperature  produced  by  its  combustion,  and  therefore 
the  flame  is  not  hot  enough  to  set  fire  to  the  adjacent  gas. 
In  the  experiments  shown  at  the  Soiree  of  the  Royal  Society,  on 
June  15,  an  electric  current  of  65  volts  and  15  amperes,  alter- 
nating 130  times  a  second,  was  passed  through  the  primary  of  a 
large  induction  coil,  when  an  arching  flame,  consisting  chiefly  of 
burning  nitrogen,  issued  from  each  of  the  secondary  poles,  meeting 
at  the  centre.  When  once  started  the  poles  can  be  drawn  asunder 
till  the  flame  bridges  across  212  mm.  When  the  terminals  are 
more  than  46  mm.  apart,  the  flame  will  not  strike  across.  When 
alight  the  flame  is  easily  blown  out  by  the  breath,  and  it  can  then 
be  re-lighted  by  a  taper. 
In  the  spectroscope  the  flame  of  nitrogen  shows  no  lines,  the 
spectrum  being  faint  and  continuous.  The  temperature  is  a  little 
higher  than  that  of  a  good  blow-pipe  flame,  easily  melting  fine 
platinum  wire.    The  hot  gases  rising  from  a  flame  have  a  strong 
