152 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY^ (SERIES XIII.) 



that the diminution of convective effect, consequent upon the high conducting power 

 of the metallic media used in these experiments, might be fully compensated for by 

 the enormous quantity of electricity passing. In fact, it is impossible not to expect 

 some effect, whether sensible or not, of the kind in question, when such a current is 

 passing through a fluid offering a sensible resistance to the passage of the electricity, 

 and, thereby, giving proof of a certain degree of insulating power (1328.). 



1604. I endeavoured to connect the convective currents in air, oil of turpentine, &c. 

 and those in metals, by intermediate cases, but found this not easy to do. On taking 

 bodies, for instance, which, like water, acids, solutions, fused salts or chlorides, &c., 

 have intermediate conducting powers, the minute quantity of electricity which the 

 common machine can supply (371. 861.) is exhausted instantly, so that the cause of 

 the phenomenon is kept either very low in intensity, or the instant of time during 

 which the effect lasts is so small, that one cannot hope to observe the result sought for. 

 If a voltaic battery be used, these bodies are all electrolytes, and the evolution of gas, 

 or the production of other changes, interferes and prevents observation of the effect 

 required. 



1605. There are, nevertheless, some experiments which illustrate the connection. 

 Two platina wires, forming the electrodes of a powerful voltaic battery, were placed 

 side by side, near each other, in distilled water, hermetically sealed up in a strong 

 glass tube, some minute filaments being present in the water. When, from the evo- 

 lution of gas and the consequent increased pressure, the bubbles formed on the elec- 

 trodes were so small as to produce but feebly ascending currents, then it could be 

 observed that the filaments present were attracted and repelled between the two wires, 

 as they would have been between two oppositely charged surfaces in air or oil of tur- 

 pentine, moving so quickly as to displace and disturb the bubbles and the currents 

 which these tended to form. Now I think it cannot be doubted that under similar 

 circumstances, and with an abundant supply of electricity, of sufficient tension also, 

 convective currents might have been formed ; the attractions and repulsions of the 

 filaments were, in fact, the elements of such currents (1572.), and therefore water, 

 though almost infinitely above air or oil of turpentine as a conductor, is a medium in 

 which similar currents can take place. 



1606. I had an apparatus made (fig. 28.) in which a is a plate of shell-lac, h a fine 

 platina wire passing through it, and having only the section of the wire exposed above; 

 c a ring of bibulous paper resting on the shell-lac, and d distilled water retained by 

 the paper in its place, and just sufficient in quantity to cover the end of the wire b ; 

 another wire, e, touched a piece of tin foil lying in the water, and was also connected 

 with a discharging train; in this way it was easy, by rendering b either positive or 

 negative, to send a current of electricity by its extremity into the fluid, and so away 

 by the wire e. 



1607. On connecting b with the conductor of a powerful electrical machine, not 

 the least disturbance of the level of the fluid over the end of the wire during the 



