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

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1510.  The next set of results are those obtained when the intervals n and o (fig. 131.) 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 o; 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 n 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 o = 0.4 of an inch:  A, B inductric positive, discharge at both intervals, most at n, by positive sparks; A, B inductric negative, discharge equal at n and o.  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 o 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, discharge nearly equal; inductric negative, discharge mostly at n by negative brush.  Made the intervals = 0.8 of an inch:  A, B inductric positive, discharge both at n and o; 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 = 0.8 of an inch:  A and B inductric positive, discharge mostly at n, as positive brush; inductric negative, discharge mostly at o, as positive brush.  Here the positive discharge seems most facile.

1515. Coal gas.—­n and o = 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, discharge mostly at o by negative brush:  A, B inductric negative, discharge all at n by negative brush.  Here the negative discharge most facile.