on the Light emitted from various Bodies. 179 



SECTION IX. 



The Effects of Heat on spontaneous Light. 



EXPERIMENTS. 



The Light of Fishes. 



Exper. 1. One side of a luminous herring was held before the 

 fire, for a short space of time, but so as to receive its heat very 

 strongly. It was then conveyed into the laboratory ; when 

 that side which had been exposed to the fire was found quite 

 dark, but the other continued still luminous. The fish was 

 preserved till the next evening, but the extinguished light did 

 not re-appear. 



Exper. 2. A whole herring, finely shining, was thrown into 

 a quantity of boiling-hot water, and the light was immediately 

 extinguished : after keeping it there for some time, it was taken 

 out, but the light did not revive. 



The Light of shining Wood. 



Exper. 3. A piece of shining wood, its light being very faint, 

 was put into tepid water at about 90 degrees of temperature, 

 and it became in a short time much more lucid. Another piece, 

 at 96 , was rendered beautifully luminous. 



Exper. 4. A pretty thick piece of shining wood was put into 

 a gallipot, and sunk under water by means of a weight, toge- 

 ther with a thermometer, at the temperature of 64?. Boiling-hot 

 water was then added by spoonfuls; and the light, at first, was 

 rendered much more vivid, but soon after began to decrease, 

 and was apparently extinct at about no . I say apparently, be- 



A a 2 



