on the Light emitted from various Bodies , 419 
the light was extinguished in less than an hour. The experiment 
was repeated in the same gas, and with the same result. 
Exper. 4. A cork, illuminated with mackerel-light, was intro- 
duced into the same quantity of gas ; and was dark in half an 
hour. 
Exper. 5. A fragment of shining wood, being put into the 
gas, became dark in eight minutes. A second piece became 
dark in live minutes. They were then taken out, and conti- 
nued dark all that evening. On the next evening, one of the 
pieces was uncommonly lucid. 
Exper. 6 . At 10 P. M. another fragment of brightly shining 
wood was introduced above water, into 24 ounces of the gas, 
and was extinct at eleven. It was then exposed to the open air; 
but there was no return of light that evening. On the follow- 
ing night, it was found pretty luminous. 
Exper. 7. A finely shining dead glow-worm was next put 
above water, into this gas, and its light was quickly extin- 
guished. In a second experiment, in the same gas, the light 
was much slower in its extinction. In both instances, after the 
insect was withdrawn, and placed in atmospheric air, the light 
gradually revived. 
OBSERVATION. 
It is apparent, by these experiments, that sulphurated hydro- 
gen gas extinguishes spontaneous light much sooner than car- 
bonic acid gas, and that, in general, the light returns much more 
slowly, when the subject is exposed to atmospheric air. 
3 H 2 
