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

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.

* * * * *

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 o