434 Mr. E. Rutherford on the Velocity and Rate 



To determine N an E.M.F. of 200 volts was applied to the 

 lower plate the instant after the rays had ceased. The two 

 shunt-levers were close together, and the method of breaking 

 the current and applying the E.M.F. has been explained in 

 the earlier part of the paper (p. 426). The value of q was 

 determined by noting the leak per second for a saturating 

 E.M.F. of 200 volts. The value of i was obtained by apply- 

 ing an electromotive force of two or more volts to the lower 

 plate, and determining the rate of leak. 



The following table shows the values of T, j , U obtained 



for the various gases. T is expressed in seconds, U in centi- 

 metres per sec. The values of ^ are given for a potential 

 gradient of ^ of a volt per cm. between the plates. The 

 values of ^ are only approximate, and are deduced from the 



observed values on the assumption that Ohm's law holds for 

 electromotive forces small compared with the saturating 



values. The ratios of -= were determined for different electro- 

 motive forces in the different gases. For example, the 

 value of yfor hydrogen was *32 for 1'4 volts acting between 

 the plates, while the value of y for sulphur dioxide was '066 

 for 9*3 volts acting between the plates. 

 Table of Velocities. 



Gas. 



Hydrogen 



Oxygen 



Nitrogen 



Air 



Carbonic Acid Gas 

 Sulphur Dioxide .. 



Chlorine 



Hydrochloric Acid Gas. . . 



T. 



I" 



•4 



■108 



•4 



•021 



•31 



019 



•29 



•019 



•34 



015 



•17 



•0033 



•21 

 •18 



•0085 

 •01 



Velocity, U. 



cms. 

 10-4 



2-8 



3 2 



32 



215 



•99 



2 



2-55 



