being just short of this degree of exhaustion. The probable
explanation is that the vagrant molecules I introduce in the next
experiment, happening to come within the sphere of influence of the
positive pole, rush violently to it, and excite phosphorescence in the
yttria, while losing their negative charge.

* * * * *

[Continued from SUPPLEMENT, No. 794, page 12690.]




GASEOUS ILLUMINANTS.[1]

[Footnote 1: Lectures recently delivered before the Society of Arts,
London. From the _Journal_ of the Society.]

By Prof. VIVIAN B. LEWES.


V.

Having now brought before you the various methods by which ordinary
coal gas can be enriched, so as to give an increased luminosity to the
flame, I wish now to discuss the methods by which the gas can be
burnt, in order to yield the greatest amount of light, and also the
compounds which are produced during combustion.

In the first lecture, while discussing the theory of luminous flames,