which, with a certain interval, was bright; with a larger interval, was
straight across and flamy, like a very exhausted and sudden, but not a
dense sharp spark; and with a still larger interval, produced a feeble
brush on the inductric positive end, and a glow on the inducteous negative
end, the dark part being between (1544.); and at such times, the spark at
the conductor, instead of being sudden and sonorous, was dull and quiet
(334.).

1555. On introducing more muriatic acid gas, until the pressure was 29.97
inches, the same terminations gave bright sparks within at small distances;
but when they were about an inch or more apart, the discharge was generally
with very small brushes and glow, and frequently with no light at all,
though electricity had passed through the gas. Whenever the bright spark
did pass through the muriatic acid gas at this pressure, it was bright
throughout, presenting no dark or dull space.

1556. In _coal gas_, at common pressures, when the distance was about an
inch, the discharge was accompanied by short brushes on the ends, and a
dark interval of half an inch or more between them, notwithstanding the
discharge had the sharp quick sound of a dull spark, and could not have
depended in the dark part on _convection_ (1562.).

1557. This gas presents several curious points in relation to the bright
and dark parts of spark discharge. When bright sparks passed between the
rod ends 0.3 of an inch in diameter (1544.), very sudden dark parts would
occur next to the brightest portions of the spark. Again with these ends
and also with balls (1422.), the bright sparks would be sometimes red,
sometimes green, and occasionally green and red in different parts of the
same spark. Again, in the experiments described (1518.), at certain
intervals a very peculiar pale, dull, yet sudden discharge would pass,
which, though apparently weak, was very direct in its course, and
accompanied by a sharp snapping noise, as if quick in its occurrence.

1558. _Hydrogen_ frequently gave peculiar sparks, one part being bright
red, whilst the other was a dull pale gray, or else the whole spark was
dull and peculiar.

1559. _Nitrogen_ presents a very remarkable discharge, between two balls of
the respective diameters of 0.15 and 2 inches (1506. 1518.), the smaller
one being rendered negative either directly inducteously. The peculiar
discharge occurs at intervals between 0.42 and 0.68, and even at 1.4 inches
when the la