DISRUPTIVE DISCHARGE — POSITIVE AND NEGATIVE DISCHARGE IN GASES. 131 



the distance between these balls and those beneath them. As to the position of the 

 balls in the jar, and their relation to each other, C and D were three and a quarter 

 inches apart, their height above the pump plate live inches, and the distance be- 

 tween any of the balls and the glass of the jar one and three quarter inches at least, 

 and generally more. The balls A and D were two inches in diameter, as before (1 493.) : 

 the balls B and C only 0'15 of an inch in diameter. 



Another apparatus was occasionally used in connection with the one just described, 

 being an open discharger (fig. 18.), by which a comparison of the discharge in air and 

 that in gases could be obtained. The balls E and F, each 0*6 of an inch in diameter, 

 were connected with sliding rods and other balls, and were insulated. When used 

 for comparison, the brass conductor was associated at the same time with the balls 

 A and B of figure 17 and ball E of this apparatus (fig. 18.) ; whilst the balls C, D and 

 F were connected with the discharging train. 



1507. I will fii*st tabulate the results as to the restraining power of the gases over 

 discharge. The balls A and C (fig. 17.) were thrown out of action by distance, and 

 the eflTects at B and D, or the interval n in the gas, compared with those at the in- 

 terval p in the air, between E and F (fig. 18.). The Table sufficiently explains itself. 

 It will be understood, that all discharge was in the air, when the interval there was 

 less than that expressed in the first or third columns of figures ; and all the discharge 

 in the gas, when the interval in air was greater than that in the second or fourth co- 

 lumn of figures. At intermediate distances the discharge was occasionally at both 

 places, i. e. sometimes in the air, sometimes in the gas. 



1508. These results are the same generally, as far as they go, as those of the like 

 nature in the last series (1388.), and confirm the conclusion that diflferent gases re- 

 strain discharge in very different proportions. They are probably not so good as the 

 former ones, for the glass jar not being varnished, acted irregularly, sometimes taking 

 a certain degree of charge as a non-conductor, and at other times acting as a con- 

 ductor in the conveyance and derangement of that charge. Another cause of dif- 

 ference in the ratios is, no doubt, the relative sizes of the discharge balls in air; in 

 the former case they were of very different size, here they were alike. 



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