M. B. W. Feddersen on the Electric Spark. 511 



II. Measurement of the eliminated quantities' of Electricity in a 

 total discharge. 



In considering the relation of the clifiiinated electricity to the 

 entire original electricity on discharging a Leyden jar through 

 a resistance of given magnitude, I hay'e not had an opportunity 

 of varying the resistances sufficientiy.' I intended therefore to 

 discuss this question on another occasion, after the further exa- 

 mination of the phaenomena underexamination. The close connec- 

 tion, however, subsisting between this question and what has been 

 above considered, determines me to communicate the two series 

 of observations which I have as yet had an opportunity of making. 

 The quantity of electricity cUminated on discharging a Leyden 

 jar appears, it is true, for small resistances of the completing cir- 

 cuit, and with the most various charges, to be always a definite 

 aliquot part of the latter. This constant character is, however, 

 completely lost on the introduction of very great resistances. 



The quantity of electricity eliminated by a discharge* was 

 determined by measuring how much the 16-millim. thick sphere 

 of the spark-micrometer had to be approximated in'order that,after 

 a discharge, a second, third, fourth, &c. discharge might be ob- 

 tained f. 



* It was hero necessary that tlic jar shouUl not have containeil, a short 

 time previously, a charge mucli greater than that emiiloycd in the experU 

 ment; for otherwise tlie alwiiys inconstant residue, the theory of which has 

 been given by Kohlrausch (PoggendorfF, vol. xci. pp. 56 and 17.9), would 

 have produced a considerable effect. 



t Although the distance of dischai-gc does not offer a satisfactory mea- 

 sure for the quantity of charge and discharge, yet I have hesitated to em- 

 ploy a reduction from the charge of a measuiing jar, given in the first de- 



