On the Light /rem organifed Bodies. 455 



Tie Light of fining Wood. 



JExpey. 3. A fragment of fliining wood was put into a fmall wide-mouthed phial, which 

 was plunged into a frigorific mixture. As the cold afFefted the wood, the light gradually 

 faded, and at laft was totally imperceptible. The phial was then taken out, and placed in 

 water at about 62° ; by this change of temperature, the frozen wood gradually thawed, 

 and then regained its former luftre. 



The Light of Glow-vjortns, 



Exper. 4. A fmall phial, containing a luminous dead glow-worm, was expofed to the 

 cold of the frigorific mixture ; as the coldnefs penetrated the phial, the light diminiflied, 

 and at length was totally extinft. But, by placing the phial in water at about 62", the 

 glowing property of the infeft foon returned. In this experiment, the glow-worm was 

 evidently congealed ; for it adhered to the fide of the glafs, and was covered with a hoar- 

 froft. This experiment was frequently repeated, and with the fame rcfult. 



OBSERVATION. 



By thefe experiments we learn, that cold extinguiflies fpontaneous light in a temporary 

 manner, but not durably, as the fubftances of the third fe£lion do; becaufe the light 

 revived again in its full fplendour, as foon as it was expofed to a moderate degree of 

 temperature. 



SECTION IX. 



The EffeEls of Heat on fpontaneous Light. 

 EXPERIMENTS. 



The Light of Fifhes, 



Exper. 1. One fide of a luminous herring was held before the fire, for a fhort fpace of 

 time, but fo as to receive its heat very ftrongly. It was then conveyed into the laboratory ; 

 when that "fide which had been expofed to the fire was found quite dark, but the other 

 continued ftill luminous. The fi(h was preferved till the next evening, but the ex- 

 tinguiflied light did not re- appear. 



Exper. 2. A whole herring, finely fhining, was thrown into a quantity of boiling-hot 

 water, and the light was immediately extinguiflied : after keeping it there for fome time, 

 it was taken out, but the light did not revive. 



The 



