32 
Oxidation  of  Nitrogen. 
Am.  Jour.  Pharm. 
January,  1915. 
than  they  are  in  solutions,  although  here  the  reactions  may  not  be  as 
simple  as  they  are  sometimes  represented.  The  spectroscope  is  be- 
ginning to  show  indications  that  the  light  centres  are  more  numerous 
than  the  possible  number  of  atom,  ion,  and  molecule  types.  In  the 
case  of  nitrogen  we  have  various  types  of  line  spectra,  and  quite 
recently  Grotrian  and  Runge  2  have  made  convincing  claims  that  the 
so-called  cyanogen  spectrum  is  due  to  nitrogen.  (These  experiment- 
ers worked  with  large  Schonherr  arcs  about  a  metre  in  length.) 
Chemical  Reaction  Centres. 
Under  conditions  such  as  exist  in  the  arc,  spark,  or  whenever  the 
temperature  is  high,  many  kinds  of  "  centres  "  may  exist.  These 
"  centres  "  may  be  the  sources  of  light  and  heat  emission  or  absorp- 
tion, the  ions  that  show  deflections  by  electric  and  magnetic  fields, 
and  the  particles  that  take  part  in  chemical  reactions.  It  must  not 
necessarily  be  assumed  that  the  "  centres  "  of  the  various  physical 
phenomena  are  the  same.   They  may  be  widely  different. 
Among  the  centres  which  may  exist  in  arcs  and  sparks  and  which 
have  been  shown  to  exist  in  vacuum  tubes  are 
-   -  +  ++++ 
o2,  o,  o,  o3,  o6,  o,  o,  02, 
++  + 
N,  N, 
+    +  +++ 
N2,  N3,  N,  N,  N2. 
Negative  electrons  also  exist  in  comparatively  large  numbers. 
The  formation  of  nitric  oxide  in  the  electric  discharge  may  take 
place  in  a  large  number  of  ways.  Some  of  these  possible  chemical 
reactions  are  as  follows : 
-f  N  +  e+  e  +  e  =  NO  (1) 
+  N  =  NO  (2) 
+"K  =  NO  +  N  (3) 
+ 
+  N  =  e  +  e  =  NO  (4) 
+ 
+  N  +  e  =  NO  (5) 
+ 
+  N2  +  e  =  NO+N  (6) 
+++ 
+  N3  +  e  =  NO+N2  (7) 
+ 
N2  +  02  =  2NO. 
2  Phys.  Zeit.,  June  1,  1914. 
