126 Professor Faraday [May 25, 



liquid electrolytes of the power of conduction proper. Some of 

 these I will endeavour briefly to state, illustrating the subject by a 

 reference to water, which in its pure state has but a low degree of 

 electrolytic conduction. 



The ordinary phenomena of static charge and induction are well 

 known. If an excited glass rod or other body be held near a light 

 gilt sphere, suspended from the hand by a metal thread, the in- 

 ductive action disturbs the disposition of the electricity in the sphere, 

 and the latter is strongly attracted : if in place of the sphere a soap 

 bubble be employed, the same results occur. If a dish filled with 

 pure distilled water be connected with the earth by a piece of 

 moist bibulous paper, and a ball of excited shell-lac be suspended 

 two or three inches above the middle of the water, — and if a plate 

 of dry insulating gutta-percha, about eight inches long and two 

 inches wide, have its end interposed between the water and the 

 shell-lac, it may then be withdrawn and examined, and will be 

 found without charge, even though it may have touched the shell- 

 lac ; but if the end once touch the water under the lac (and it 

 may be dipped in,) so as to bring away a film of it, charged with 

 the electricity the water has acquired by the induction, it will 

 be found to possess, as might be expected, a state contrary to that of 

 the inductric shell-lac. 



In order to exclude any conducting body but water from what 

 may be considered as a reference experiment, two calico globular 

 bags with close seams were prepared ; and being wetted thoroughly 

 with distilled water, were then filled with air by means of a fine 

 blow-pipe point ; they were then attached to two suspending bands 

 of gutta-percha, by which they were well insulated, and being about 

 three inches diameter they formed, when placed in contact, a double 

 system six inches in length. A metallic ball, about four inches in 

 diameter, was connected with the electric machine to form an induc- 

 tric body, an uninsulated brass plate was placed about nine inches 

 off to form an inducteous body ; between these the associated water 

 balls could be placed so as to take part in the induction, and when 

 the electric charge was so low that the moist atmosphere caused no 

 transmission of electricity, the balls could be introduced into position 

 and brought away without having received any permanent charge. 

 Under these circumstances if the associated balls were brought into 

 the place of induction, were then separated, withdrawn, and ex- 

 amined, they were found, the one charged positively and the other 

 negatively, by electricity derived from themselves, and without 

 conductive or convective communication with any other substance 

 than their own water. 



It is well known indeed that by the use of water we may replace 

 metal in all electro-static arrangements, and so form Leyden jars, 

 condensers, and other induction apparatus, which are perfect in 

 principle though with imperfect action. The principles are the 

 same, whether water or metals be used for conductors, and the 



