arbonic acid, muriatic acid,
sulphurous acid and ammonia. I thought also that I obtained it in oil of
turpentine, but if so it was very dull and small.

1535. The glow is always accompanied by a wind proceeding either directly
out from the glowing part, or directly towards it; the former being the
most general case. This takes place even when the glow occurs upon a ball
of considerable size: and if matters be so arranged that the ready and
regular access of air to a part exhibiting the glow be interfered with or
prevented, the glow then disappears.

1536. I have never been able to analyse or separate the glow into visible
elementary intermitting discharges (1427. 1433.), nor to obtain the other
evidence of intermitting action, namely an audible sound (1431.). The want
of success, as respects trials made by ocular means, may depend upon the
large size of the glow preventing the separation of the visible images:
and, indeed, if it does intermit, it is not likely that all parts intermit
at once with a simultaneous regularity.

1537. All the effects tend to show, that _glow_ is due to a continuous
charge or discharge of air; in the former case being accompanied by a
current from, and in the latter by one to, the place of the glow. As the
surrounding air comes up to the charged conductor, on attaining that spot
at which the tension of the particles is raised to the sufficient degree
(1370. 1410.), it becomes charged, and then moves off, by the joint action
of the forces to which it is subject; and, at the same time that it makes
way for other particles to come and be charged in turn, actually helps to
form that current by which they are brought into the necessary position.
Thus, through the regularity of the forces, a constant and quiet result is
produced; and that result is, the charging of successive portions of air,
the production of a current, and of a continuous glow.

1538. I have frequently been able to make the termination of a rod, which,
when left to itself, would produce a brush, produce in preference a glow,
simply by aiding the formation of a current of air at its extremity; and,
on the other hand, it is not at all difficult to convert the glow into
brushes, by affecting the current of air (1574. 1579.) or the inductive
action near it.

1539. The transition from glow, on the one hand, to brush and spark, on the
other, and, therefore, their connexion, may be established in various ways.
Those circumstances wh