166 M. Henrici ow the Theory and Applicatiofi of Electricity, 



are different kinds of light, heat and sound. Electrical phse- 

 nomena would then also be undulatory. We certainly do not 

 readily see how the positive and negative could in this way be 

 accounted for; but such a difficulty cannot justify us in re- 

 jecting an explanation in other respects so accordant with 

 reason. Viewed in this light, the increased effect produced 

 by the simultaneous action of several sources of electricity 

 (the voltaic pile, the electrical battery) would be considered 

 as caused in the same way, as by the simultaneous action of 

 many sources of the same kind of light an increased illumina- 

 tion occurs, and in the simultaneous emission of several sounds 

 an increase in the sound conveyed to the ear is produced. 

 The action of the condenser would then be intelligible as con- 

 verting electricity of less into that of higher tension. 



I may be permitted here to draw attention to the facts 

 which electrical phsenomena seem to point out, that an essen- 

 tially different mode of propagation of the electricity occurs in 

 the so-called non-conductors to what takes place in the con- 

 ductors. Thus it appears that in the former, when they 

 allow the electricity to be diffused to any extent, as the air, 

 its propagation follows the same laws as light and radiant 

 heat; this is especially pointed out by the late experiments of 

 Petrina, who found that electricity, when propagated in a rec- 

 tilinear direction in the atmosphere, in passing by a screen (a 

 metallic conducting plate connected with the earth), suffers dif- 

 fraction, just as rays of light and heat do. Hence any sub- 

 stance would be so much a better or worse conductor than 

 another as it was suitable to either one or the other method 

 of propagation of the electricity ; with imperfect conductors 

 both must occur to a certain extent. In other respects the 

 non-conductors of electricity can only be compared within 

 narrow limits with transparent bodies, because in the former 

 the diffusion of the electricity will always be proportionally 

 very limited; the so-called non-conductors of electricity will 

 always be comparatively opake substances when considered 

 electrically. It must also be admitted that they may be com- 

 pelled by a sufficiently strong electrical power to propagate 

 the electricity by conduction through more or less limited 

 spaces (electric sparks, lightning). It moreover deserves to 

 be noticed, that there is no conduction of heat and light in 

 the same sense as occurs with electricity. We are unac- 

 quainted with any diffusion of light within bodies which can 

 be compared to the conduction of electricity, and the diffusion 

 of heat within bodies not only obtains with infinitely less ra- 

 pidity, but also according to entirely different laws from the 

 conduction of electricity (the same holds good with sound). 



