588 Recovery of Residual Charge in Electric Condensers. 



dead-beat. A sufficient current was then obtained, which 

 was read at frequent intervals until too small to be observed. 

 Two persons were required for this — one to note when the 

 spot of light passed the divisions on the scale, the other to 

 take the time of doing so. 



It was always found possible to fit a hyperbola to the 

 observations so obtained. One of the series (Table VIII.) of 

 observations is shown plotted in fig. 9. The curve 



C = 2304 ' 4 

 t + S'U 



was found to suit these observations, and is there shown. 

 The experimental points are seen to tit the curve in a most 

 satisfactory way. 



Table VIII. 



c. 



/. 



C. 



t. 



258 







25 



79 



208 



3 



23 



87 



158 



7 



21 



97 



108 



13 



18 



115 



78 



21 



16 



134 



58 



30 



14 



155 



48 



38 



12 



184 



43 



43 



11 



203 



38 



49 



10 



222 



33 



58 



9 



251 



28 



69 







In these experiments, since the condenser was practically 

 short-circuited, there was comparatively speaking no dif- 

 ference in potential between the plates throughout the 

 recovery; so that the dielectric recovered at its maximum or 

 normal rate. 



These and the experiments in the first part of the paper are 

 in accordance with the analogy of recovery of elastic solids 

 from overstrain. The quantity of electricity recovered up 

 to any time t is given by an expression of the type 



Q = a log (t + h), 



which is the expression found by Rankine and others to fit 

 the recovery from overstrain in elastic bodies. 



