EXPERIMENTS WITH IONIZED A IK. 



49 



time for whicli it holds. If the process is repeated to get the ratio of increments 

 Sc and St of the values just found, the rates 6c/dt. of the table follow. These are 

 practically constant in the same series but differ widely in successive series, i. e. 

 varying with c'. Let the mean c' of each I'atio be found as in the table. Then if 

 dc'/St be computed, a result is obtained which though iioi fully independent of c' is 

 I'estricted to nari'ow limits. Thus in place of the above equation there follows (per 

 unit of c, A, and x, as above) a double exponential law, 



F„ 



^'^0*- 





expressing that some independent cause has for the time 7' been decreasing the 

 number of particles at the rate r. If c corresponds to 6' as n cori'esponds to N, C/c— 

 20vriog.;_ The last column shows the values of 6' found in this way. Compared 

 with c they are constant enough to plausibly suggest some independent cause of 

 decay attributable to the source. 



8. Effect of distance between condenser lylates. — I come now to the main 

 pui'pose of the present paper, namely, to find and to explain the decrease of the 

 leakage, t', of the condenser when the plates are separated. This is equivalent to 

 finding the change of «, the number of jiai-ticles 2)er cubic ceutim. with the distance 

 between the condenser plates. The farther away the ions move normally from the 

 condenser plate the fewer will have survived, whether this be due to mutual de- 

 struction or other decay oi- to the escape of particles laterally out of the condenser. 



Table 6 gives the distance apart, ;r, of the condenser plates, the current time 

 (date), and the interval, t, elapsed since charging, together with the voltages, V 

 (potential difference of the condenser), corresponding. The constant c' is comp)uted 

 from 1"=: T'^,10"'''', for the time, /, given in minutes. The last column contains the 

 values, T", computed from v . The fall of potential for the dift'ei'ent distances, a", is 

 shown in the chart, figure 5. 



TABLE 6.— RATES OF DISCHARGE FOR DIFFERENT DISTANCES BETWEEN PAR- 

 ALLEL PLATES, WHEN ONE PLATE (GRATING) IS THE SOURCE OF 

 PHOSPHORUS EMANATION. PLATES 14 CM. SQUARE. V -V,io-'=''. 



