196 J. Trowbridge — Oscillatory discharge, etc. 



In the case of one cell of the battery the polarization capac- 

 ity is undoubtedly very large. C. M. Gordon* finds that the 

 polarization capacity of two surfaces of platinum 0'65 cm2 sepa- 

 rated by an interval of 2 mm amounts to more than 50 micro- 

 farads. The cells of my battery consist of lead plates of 

 about 10 cm2 surface separated by about 6 mm . The layer of 

 peroxide of lead undoubtedly gives a large polarization 

 capacity. The resistance of each cell is about one quarter 

 of an ohm. Even with this small value of R, oscil- 

 lating currents such as my experiments show arise when 

 the battery discharges through air or gases. A large portion 

 of the oscillating currents pass through the condenser circuit, 

 and the electrolyte acts as a semi-insulator. With a very 

 high value of p, no current would pass through the electrolyte 

 and the cells would therefore act like Leyden jars. In the case 

 I am considering the Plante cells evidently act like leaky Ley- 

 den jars coupled in series. If C is the apparent capacity of 



one cell — would be the capacity of n cells. 



An examination of the photographs of the oscillations pro- 

 duced by 2500 cells, showed an apparent capacity of about 

 1000 electrostatic units. Five thousand cells gave an apparent 

 capacity of about 500 electrostatic units, as should be the case. 

 The small apparent capacity C results from the leaking of the 

 condenser due to the conduction through the electrolyte. 



Since the discharge from an accumulator of a large number 

 of cells is, in general, oscillatory, I am led to the belief that 

 the discharge from any primary battery is also oscillatory, for 

 in all cases we have to deal with capacity and self-induction. 

 It is evident that a galvanometer in circuit with a Geisler tube 

 or a telephone cannot detect the oscillatory discharge, since 

 it is of high period. Moreover when a Geisler tube is lighted 

 by a large battery with no resistance save that of the Geisler 

 tube and the battery in the circuit, and the light is examined 

 in a revolving mirror by the eye, no oscillations or intermit- 

 tance of light can be perceived on account of the naming dis- 

 charge through the rarified gas. 



The oscillatory discharge may be said to be the common 

 occurrence of nature in the case of electrical discharges and 

 the one direction discharge the uncommon. This has been 

 expressed by the remark that electricity takes the path of least 

 resistance; this common belief, however, must be modified 

 under certain conditions of resonance. In general nature 

 avoids a unidirectional discharge. 



Jefferson Physical Laboratory, Harvard University. 



*Wied. Ann., No. 5, 1897, p. 28. 



