4iS Dr. Hulme's Experiments and Observations 
OBSERVATION. 
This gas, we find, has also an extinguishing property, with 
respect to spontaneous light ; but, in general, the light returns, 
if the object of experiment be taken out, and exposed to the 
open air. 
§ vi. 
The Effects of sulphurated hydrogen Gas * on spontaneous Light. 
EXPERIMENTS. 
Exper. l. At noon, a piece of a very fresh mackerel, with 
a bright eye, was introduced above water, into 24 ounces 
of this gas, and was retained therein for three successive 
evenings, without emitting any light. It was then exposed to 
atmospheric air; yet it continued dark on the two following 
nights : but, on the third, it was very luminous, and remained 
so on the fourth and fifth. 
Exper. 2. The same experiment was then made with a piece 
of fresh herring, which was also kept in the above gas, for 
about three nights, without being luminous. After exposure to 
common air, it did not emit any light during the first 24 hours. 
However, on the subsequent night, it began to shine, had a very 
bright light on the following evening, and continued shining for 
several succeeding nights. 
Exper. 3. A cork, smeared with the luminous matter of a 
herring, was put above water, into 24 ounces of the gas ; and 
• This gas was obtained from sulphuret of potash and diluted muriatic acid. 
