Mr. J. Prideaux on the Theory of Voltaic Action, 251 



piece of rag at the bottom of the pendulum, set fire to the rag, 

 and blow out the flame, still allowing the rag to smoke ; then 

 put the pendulum in motion, and the smoke will be seen pass- 

 ing along in the direction of the pendulum's motion, even be- 

 fore it can be observed that it has begun to descend. 



Had Captain Kater been aware of this fact, he would have 

 been at no loss to account for his pendulum losing its adjust- 

 ment, when by the hygrometer he observed a great and sud- 

 den change in the air from moisture to dryness. This obser- 

 vation shows the accuracy with which his experiments were 

 conducted ; it also indicates that dry air is more dense than 

 moist, as the current generated in the latter state offered more 

 resistance to the return of the pendulum than in the former. 



For, in his experiments, at the time when the smaller weight 

 of the pendulum was down, the vibrations would be slower 

 than when the greater weight was down ; the smaller weight 

 presenting a larger surface to the resisting medium, in propor- 

 tion to its weight, than the greater weight, the current then 

 generated would oppose its descent more than the current 

 generated by the greater weight. 



[To be continued.] 



XLI. On the Theory of Voltaic Action. By Mr. John 

 Prideaux. 



[Concluded from p. 220.] 



Sect. IV. Of the Conducting Property of the Liquid. 



25. r T , HE conducting power of the liquid is a main point 



*■ in voltaic phaenomena; and acid liquids are under- 

 stood, generally, to be the best conductors (liquid metals 

 of course left out of the question); alkaline liquids the worst, 

 of aqueous solutions; and alcohol, oils, and the like, as non- 

 conductors. Thus, from whatever kind of coincidence, the 

 conducting and electro-negative properties seem to bear some 

 mutual relation. 



26. Whether this conduction in the voltaic battery be from 

 particle to particle, or, like that of caloric in liquids, con- 

 nected with transference of the particles themselves, becomes 

 the next inquiry. Of such transference we have abundant 

 evidence; but in what degree it is essential to the conducting 

 process, it may be difficult to ascertain by direct experiment. 



27. Separate glasses, filled with acid and alkaline solutions, 

 and connected by a siphon filled with water, separated cells, 

 similarly filled, and divided by bladder, each having a copper 

 plate plunged in the alkali, a zinc plate in the acid, and con- 



2 K 2 



