on the Light emitted from various Bodies. 415 
exposed to the open air, and the light revived as before. It was 
then reinstated and extinguished, and continued in a dark state, 
from the third to the fifth night, when, being again taken out, 
it soon shone in a pretty vivid manner. It was again intro- 
duced and extinguished as usual ; and no observation was made 
of it, from some accidental circumstance or other, until the 10th 
of November in the evening, when it was taken out, and ex- 
posed to the open air for a length of time, but the light did not 
revive. 
Exper. 13. A third fragment, somewhat larger than the for~ 
mer, and equally luminous, was put above water, at the same 
time as the one in the last experiment, where it was soon de- 
prived of its light. It was retained there, in a dark state, from 
the 2d of October till the 10th of November; it was then taken 
out, and exposed to the action of atmospherical air. for several 
days, but there was no return of light. 
Exper. 14. About 7 P. M. a shining dead glow-worm was 
introduced above water into the gas, and its light was soon 
extinct. It was then exposed to the open air* where, in a very 
short time, it shone as brightly as before. 
Exper. 15. At half an hour past 9 P. M. the same glow-worm 
was again introduced above water ; when its light in a short time 
disappeared. It was taken out for exposure to common air at 
11, and its glowing property was immediately restored. It was 
again replaced in the gas, where it soon lost all its light a se- 
cond time, and was kept in that dark state for 24 hours ; when 
taken out, it continued dark fora little time, and then the insect 
gradually recovered its pristine splendour. 
