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ELECTRICAL DISCHARGES.
Pro fessor Grant delivered a lec- <*>
ture entitled "Electrical Discharges in
Gas es," be fore the Commonwealth
Club in the Physics theatre, Univer-
■wy. on imaay evening. i
The lecturer said as a rate air and
other Rases would not allow an elec
tric current to pass through them, but
under the influences of certain agen
cfes they would allow electrical dis
<*af«w *? tfJteplaoe. The more Im
portant of these agencies were com
bustion, action, of the rays of radium
"f ,?* hS rJ?^- Ilctlve s???stances. ultra
violet light. X-rays, &c. Experiments!
wwre made by the lecturer to^tustrate
this. The nature of the electric spark
w« «Sl am:«>. Experiments shd^ed
the effect of reducing the pressure of
air. Reference was made to the exis
tence of electrons, which were consti
tuents of every species of material
atom. These electrons existed even in
free air. but only transiently, for they
attached themselves to the atoms of
air. In the higher evacuated spaces
the electrons could exist for longer in
tervals of time and produced remark
able effects. Luminescence, heat, and
X-rays were produced. It was neres
tary to produce electrons in order thnt
an electric discharge might pass. Thi1!
would be done by heating a metal wire
to incandescence, or by allowing Ugh*.
partiulariy ultra violet licht. to fall
upon the surface of a metal plate.
A demonstration was given of the
' hip-h potential discharge from a Tesla
' coU.
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