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



question (1523.). I expe(;t that the effects are due altogether to the mode in which 

 the particles of the interposed dielectric polarize, and I have already given some ex- 

 perimental indications of the differences presented by different dielectrics in this 

 respect (1475. 1476.). The modes of polarization, as I shall have occasion hereafter 

 to show, may be very diverse in different dielectrics. With respect to common air, 

 what seems to be the consequence of a superiority in the positive force at the surface 

 of the small ball, may be due to the more exalted condition of the negative polarity 

 of the particles of air, or of the nitrogen in it (the negative part being, perhaps, more 

 compressed, whilst the positive part is more diffuse, or vice versd) ; for such a con- 

 dition could determine certain effects at the positive ball which would not take place 

 to the same degree at the negative ball, just as well as if the positive ball had pos- 

 sessed some special and independent power of its own. 



1504. That the effects are more likely to be dependent upon the dielectric than the 

 ball, is supported by the character of the two discharges. If a small positive ball be 

 throwing off brushes with ramifications ten inches long, how can the ball affect that 

 part of a ramification which is five inches from it ? Yet the portion beyond that place 

 has the same character as that preceding it, and no doubt has that character im- 

 pressed by the same general principle and law. Looking upon the action of the con- 

 tiguous particles of a dielectric as fully proved, I see, in such a ramification, a propa- 

 gation of discharge from particle to particle, each doing for the one next it what was 

 done for it by the preceding particle, and what was done for the first particle by the 

 charged metal against which it was situated. 



1505. With respect to the general condition and relations of the positive and ne- 

 gative brushes in dense or rare air, or in other media and gases, if they are produced 

 at different times and places, they are of course independent of each other. But 

 when they are produced from opposed ends or balls at the same time, in the same 

 vessel of gas (1470. 1477.)3 they are frequently related ; and circumstances may be so 

 arranged that they shall be isochronous, occurring in equal numbers in equal times ; 

 or shall occur in multiples, i. e. with two or three negatives to one positive ; or shall 

 alternate, or be quite irregular. All these variations I have witnessed ; and when it 

 is considered that the air in the vessel, and also the glass of the vessel, can take a 

 momentary charge, it is easy to comprehend their general nature and cause. 



1506. Similar experiments to those in air (1485. 1493.) were made in different gases, 

 the results of which I will describe as briefly as possible. The apparatus is represented 

 fig. 17. consisting of a bell-glass eleven inches in diameter at the widest part, and ten 

 and a half inches high up to the bottom of the neck. The balls are lettered, as in fig. 16, 

 and are in the same relation to each other ; but A and B were on separate sliding 

 wires, which, however, were generally joined by a cross wire, w, above, and that con- 

 nected with the brass conductor, which received its positive or negative charge from 

 the machine. The rods of A and B were graduated at the part moving through the 

 stuffing-box, so that the application of a diagonal scale applied there, told what was 



