I I RNACE REACTIONS UNDER HIGH OASKors I'l.'KSSURES. 



indicates that the electrical conditions more nearly approach those of a resistance 

 than of a true arc. 



It is, however, almost inconceivable that a power of 5 or 10 kilowatts (see fig. 10, 

 B and C) can be expended in such a limited volume of solid material without 

 volatilising it; and, as we shall see, the amount of disruption as evidenced by the 

 feed required is under these conditions extremely small. 



Negative 

 electrodes. 



Positive 



divtrodes. 



123 4 



Fig. 9. Photograph of carbon electrodes after use. (Horizontal arc.) 



No. 



1 

 2 

 3 

 4 



Pressure, Current, 

 atmospheres, amperes. 



30 

 30 

 50 

 48 



60 

 400 

 100 

 120 



E.M.F., 

 volts. 



60 



65 



100 



130 



Gas. 



Originally air, but all oxygen fixed by carbon. 



Ditto. 



Coal gas. 



Originally air, but all oxygen fixed by carbon. 



With an exceptionally high current density the arc in a non-oxidising gas at high 

 pressure gives a well-defined flame. 



In fig. 10, D, a comparison is given between arcs in carbon monoxide at 11 and 16 

 atmospheres and an experiment made by Mrs. AYRTON* with an enclosed arc at 

 ordinary pressure, using carbons of similar size. It will be seen that the increase of 

 voltage due to an increase of pressure of 1 o atmospheres is very considerable. For 



VOL. ccvii. A. 



* Mrs. AYKTON, ' The Electric Arc,' p. 304. 

 3 K 



