ACTION OF THE ELECTRIC SPARK. 



221 



Third Section. Action of the Voltaic Arc and the Electric Spark. 



1. We shall now study the action of electricity under its 

 various forms in bringing about nitrogenous combinations, by 

 acting upon nitrogen in presence of the other elements. 



Under the form of the voltaic arc, or the spark, electricity 

 produces in fact the union of nitrogen with oxygen (synthesis 

 of the nitric compounds), the union of nitrogen with hydrogen 

 (synthesis of ammonia), the union of nitrogen with acetylene 

 (synthesis of hydro- 

 cyanic acid). 



2. These reactions can 

 easily be produced with 

 the following apparatus, 

 which does not require 

 either the use of plati- 

 num wires fused into 

 the glass or special con- 

 ductors. Bent glass 

 tubes and free platinum 

 wires suffice. 



The following is the 



arrangement. The gas (measured or not) is placed in an ordinary 

 test-tube, in a mercury trough ; then into this test-tube are intro- 

 duced two gas- tubes, twice bent to slightly obtuse angles (Fig. 32), 

 but still keeping the same direction. The tubes being open at 

 both ends, their introduction 

 is effected without difficulty 

 and without establishing com- 

 munications with the atmo- 

 sphere. This done, a thick 

 and long platinum wire is 

 taken, of which the length 

 considerably exceeds that of 

 the bent tube, and it is intro- 

 duced by the external orifice 

 of one of the tubes, by push- 

 ing it gently through the 

 mercury which fills the tube ; 

 it is thus got past the bends Fig. 33. Action of the electric spark 

 until its end passes out of the on gases * 



internal orifice of the tube. The same operation is performed 

 with a second platinum wire slipped through the second tube. 



Two insulated conductors are thus obtained, which are put 

 into communication with the two poles of a Kuhmkorff coil, 

 or any other generator of high tension electricity. The spark 

 passes between the two points situated in the interior of the 

 test-tube, the distance and relative positionwJich can be 



