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



1509. In future experiments intended to have the character of accuracy, the in- 

 fluence of these circumstances ought to be ascertained, and, above all things, the 

 gases themselves ought to be contained in vessels of metal, and not of glass. 



1510. The next set of results are those obtained when the intervals wand o {fig. 17.) 

 were made equal to each other, and relate to the greater facility of discharge at the 

 small ball, when rendered positive or negative (1493.). 



1511. In air, with the intervals = 0*4 of an inch, A and B being inductric and 

 positive, discharge was nearly equal at n and ; when A and B were inductric and 

 negative, the discharge was mostly at n by negative brush. When the intervals were 

 = 0*8 of an inch, with A and B inductric positively, all discharge was at n by positive 

 brush ; with A and B inductric negatively, all the discharge was at w by a negative 

 brush. It is doubtful, therefore, from these results, whether the negative ball has 

 any greater facility than the positive. 



1512. Nitrogen. — Intervals n and = 0*4 of an inch : A, B inductric positive, dis- 

 charge at both intervals, most at w, by positive sparks ; A, B inductric negative, dis- 

 charge equal at n and 0. The intervals made = 0*8 of an inch : A, B inductric 

 positive, discharge all at n by positive brush ; A, B inductric negative, discharge most 

 at by positive brush. In this gas, therefore, though the difference is not decisive, 

 it would seem that the positive small ball caused the most ready discharge. 



1513. Oxygen. — Intervals n and o = 0*4 of an inch: A, B inductric positive, dis- 

 charge nearly equal ; inductric negative, discharge mostly at n by negative brush. 

 Made the intervals = 0*8 of an inch : A, B inductric positive, discharge at ?i and ; 

 inductric negative, discharge all at o by negative brush. So here the negative small 

 ball seems to give the most ready discharge. 



1514. Hydrogen. — Intervals n and o = 0*4 of an inch: A, B inductric positive, 

 discharge nearly equal; inductric negative, discharge mostly at o. Intervals = 0'6 

 of an inch : A and B inductric positive, discharge mostly at n, as positive brush ; 

 inductric negative, discharge mostly at 0, as positive brush. Here the positive dis- 

 charge seems most facile. 



1515. Coal gas. — n and = 0*4 of an inch: A, B inductric positive, discharge 

 nearly all at o by negative spark : A, B inductric negative, discharge nearly all at n 

 by negative spark. Intervals = 0*8 of an inch, and A, B inductric positive, dis- 

 charge mostly at o by negative brush : A, B inductric negative, discharge all at n by 

 negative brush. Here the negative discharge most facile. 



1516. Carbonic acid gas. — wand o = 0*4 of an inch : A, B inductric positive, dis- 

 charge nearly all at o, or negative : A, B inductric negative, discharge nearly all at n, 

 or negative. Intervals = 0*8 of an inch : A, B inductric positive, discharge mostly 

 at o, or negative : A, B inductric negative, discharge all at w, or negative. In this case 

 the negative had a decided advantage in facility of discharge. 



1517. Thus, if we may trust this form of experiment, the negative small ball has a 

 decided advantage in facilitating disruptive discharge over the positive small ball in 



