38 Prof. E. Wiedemann on the 



density sinks therefore very rapidly at the electrode, and only 

 small quantities of electricity can follow the first quantity. 

 But the electricity accumulated upon the machine and flowing 

 to the electrode will very soon raise the density to the neces- 

 sary point for the discharge to take place again, and without 

 large quantities of fresh electricity being produced. The 

 number of the discharges must therefore in the latter case 

 be much greater than in the first, with the same average 

 intensity of current, since in the latter case, in each discharge 

 only the quantity of electricity upon the electrode and close 

 to it is discharged, and in the former, on the contrary, the 

 quantity existing upon a much larger surface. 



The machine itself therefore acts as a sort of feeble con- 

 denser. 



But since the law relating to the difference between positive 

 and negative electricity, discovered by my father, holds good 

 both when resistances are included and without, his result 

 cannot be explained by irregularities in the action of the 

 machine, by different behaviour of the combs, and so on, 

 since these would be compensated by the condensing action 

 of the machine. We may call the discharge, when resistances 

 are included, the normal discharge ; and the quantity of elec- 

 tricity which passes over, under the same circumstances, also 

 the normal quantity, because it is just that quantity which, 

 under the precise conditions of the experiment, must be accu- 

 mulated on the electrode in order to bring about a discharge. 



Since we observe, further, that always when, without resist- 

 ances, the discharge is unstratified, it becomes stratified if 

 resistances are included, we may also conclude that "the 

 stratified discharge corresponds to the normal discharge ; " and 

 since the stratifications evidently require for their formation 

 a regular discharge, it further follows that in the normal 

 discharge the discharges occur in their simplest form. 



In exact agreement with the above we find that, when once 

 stratifications have been formed, whether with or without resist- 

 ances, these disappear as soon as an air-spark is included, the 

 quantity of electricity transmitted in each discharge being thus 

 increased. Numerous experiments showed that, as a rule, the 

 stratifications form best when the negative electrode is con- 

 nected with the machine, and the positive with the earth 

 through a large resistance. In the case of deviations of this 

 rule, which certainly occur frequently, it was always found that 

 the discharges, which were most numerous under the conditions 

 noted, gave place to less numerous discharges. The reason of 

 this could not, amongst numerous disturbing causes, always be 

 certainly determined : thus, for example, very peculiar pheno- 



