ACTIVATIOX OF ELECTRICAL COXTACTS BY ORGANIC VAPORS 797 



the theoretical value of 3 for complete decomposition of benzene into 

 carbon and hydrogen. The conclusion from this experiment is that the 

 organic material in the black activating powder is just carbon. The pre- 

 cision allows one to say that, if there is any hydrogen at all left in the 

 black powder, it does not exceed 2 hydrogen atoms for every 15 carbon 

 atoms. 



4.2 Rate of Production 



In experiments in which the energy in individual arcs was varied, by 

 using different capacitors in the range from 610 fxixi to -10,000 txjii and 

 by using the two potentials 58 volts and 232 volts, it was found that a 

 particular arc energy gives the same carbon formation per erg whether 

 the striking voltage is 232 or 58, from which one deduces that formation 

 of carbon depends upon energy rather than upon capacitance or voltage 

 separately. The amount of carbon formed per individual arc increases 

 with the energy of the arc but not so fast as linearly. The experimental 

 values M of amount of carbon formed can be related to arc energy E by 

 the empirical formula M = KE'^'^, over the range studied from 5 ergs to 

 1,250 ergs. A tentative explanation of this f power relation is given in 

 the next section. 



Starting with clean electrodes and measuring the total amount of 

 carbon formed as a function of number of arcs, it was found that the 

 rate of production of carbon is initially low but increases with time, soon 



TO 

 PUMPS 



RCA 1946 

 >- THERMOCOUPLE 

 GAUGE 



Pt BUTTONS IN 

 / MAGNETIC REEDS 



VOLUME 115 CC 



DRY ICE- 

 ACETONE BATH 



COLD TRAP FOR 

 FREEZING BENZENE 

 DURING MEASUREMENT 

 OF Hj PRESSURE 



Fig. 9 — Diagram of apparatus used by P. Kisliuk in quantitative measure- 

 ments of the decomposition of benzene vapor at arcing contacts. 



