General Science. 
m 
the same thing occurs when a drop of alcohol touches the fulmi- 
nating platinum, as prepared by Mr Edmund Davy. Light is 
also emitted when the olive oxide of silver is thrown into oxyge- 
nated water, or when balls of oxygen are broken in vacuo ; and 
similar manifestations take place when the gaseous elements se- 
parate from euchlorine ; and chloride and iodide of azote. It 
likewise appears, that light evolves under circumstances that 
seem more directly connected with condensation, as when sul- 
phur combines with potassium, copper and lead, at an elevated 
temperature, or when platinum and tin-foil unite before the 
blowpipe, and atmospheric air, oxygen, &c. are condensed in a 
glass cylinder by a piston. Light, therefore, in these experi- 
ments, seems connected with the formation of new compounds, 
or sudden extrication of chemical elements by condensation or 
expansion. I should, in much deference to the opinion express- 
ed, be inclined to consider this phenomenon either as connected 
with the compression of a portion of the air, occasioned by the 
fall of the glacier, or the production of a partial vacuum, and 
siibsequeht sudden supply by the surrounding atmosphere ; for 
when the membrane spread over the “ bladder-glass'” on the 
air-pump bursts by the superincumbent pressure, and the aif 
rushes into the void, at the same instant a flash of light is per- 
ceptible, if the experiment be mkde in the dark. The lumino- 
dty of insects, as the scohpendra^ lampyris^Julgora and linceus^ 
lunulus^ cancer^ &c. is a subject of most difficult investigation. 
If the light of insects, &c. were electrical, it should be increased 
by stimuli, as oikygen, &c. Which seems not to be the case. If 
phosphoric, it should not Cease with the death of the animal, 
but rather contiiiue, or increase on decomposition of the animal 
matter. It intermits, and therefore seems dependant on the 
will of the aiiimal, or is connected with some mechanical cause, 
mid apparently more with respiration than any other thing. 
Were it phosphorous, it should be expended in the progress of 
its slow combustion, and demand a continued supply, and con- 
stant creation of the phosphoric matter would be necessary. 
Any thing which implies material ignition is absurd ; and it 
Seems to be a phenomenon sui generis connected with a peculiar 
feature of animal physiology, as electreity is with others. Th 
light emitted from sugar, when broken in the dark, is generally 
