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



1522. This result appeared to indicate that the point which had been giving off 

 one electricity, was, by that, more fitted for a short time to give off the other. But 

 on closer examination I found the whole depended upon the inductive reaction of 

 that air, which being charged by the point, and gradually increasing in quantity be- 

 fore it, as the positive or negative issue was continued, diverted and removed a part 

 of the inductive action of the surrounding wall, and thus' apparently affected the 

 powers of the point, whilst really it was the dielectric itself that was causing the 

 change of tension. 



1523. The results connected with the different conditions of positive and negative 

 discharge will have a far greater influence on the philosophy of electrical science than 

 we at present imagine, especially if, as I believe, they depend on the peculiarity and 

 degree of polarized condition which the molecules of the dielectrics concerned ac- 

 quire (1503. 1600.). Thus, for instance, the relation of our atmosphere and the earth 

 within it, to the occurrence of spark or brush, must be especial and not accidental. 

 It would not else consist with other meteorological phenomena, also of course de- 

 pendent on the special properties of the air, and which being themselves in harmony 

 the most perfect with the functions of animal and vegetable life, are yet restricted in 

 their actions, not by loose regulations, but by laws the most precise. 



1524. Even in the passage through air of the voltaic current, we see the pecu- 

 liarities of positive and negative discharge at the two charcoal points ; and if these 

 discharges are made to take place simultaneously to mercury, the distinction is still 

 more remarkable. 



1525. It seems very possible that the striking difference recently observed and de- 

 scribed by my friend Professor Daniell*, namely, that when a zinc and a copper 

 ball, the same in size, were placed respectively in copper and zinc spheres, also the 

 same in size, and excited by electrolytes or dielectrics of the same strength and na- 

 ture, the zinc ball far surpassed the zinc sphere in action, may also be connected 

 with these phenomena ; for it is not difficult to conceive how the polarity of the par- 

 ticles shall be affected by the circumstance of the positive surface, namely the zinc, 

 being the larger or the smaller of the two inclosing the electrolyte. It is even pos- 

 sible, that with different electrolytes or dielectrics the ratio may be considerably va- 

 ried, or in some cases even inverted. 



Glow discharge. 



1526. That form of disruptive discharge which appears as a glow (1359. 1405.), is 

 very peculiar and beautiful : it seems to depend on a quick and almost continuous 

 charging of the air close to, and in contact with, the conductor. 



1527. Diminution of the charging surface will produce it. Thus, when a rod 0'3 



* Philosophical Transactions, 1838, p. 47. 



