45^ On the Light from organijtd Bodits, 



The Light of Jhining Wood. 



Expetr. 3. A piece of Ihining wood, its light being very faint, was put into tepid water 

 at about 90 degrees of temperature, and it became in a Ihort time much more lucid. 

 Another piece, at 96°, was rendered beautifully luminous. 



Exper. 4. A pretty thick piece of fhining wood was put into a gallipot, and funk under 

 water by means of a weight, together with a thermometer, at the temperature of 64". 

 Boiling-hot water was then added by fpoonfuls ; and the light, at firft, was rendered much 

 more vivid, but foon after began to decreafc, and was apparently extin£l at about 110°. 

 I fay apparently, becaufe on the next evening the light had fomewhat revived ; which 

 fliows, that the heat of 110° was not fufficient to extinguifh totally all the light inherent 

 in this piece of wood. 



Exper, 5. Finding that 110 degrees of heat did not wholly extinguifh the light of fhining 

 wood, a good many fragments, of different fizes, were then fubmitted to the power of 

 boiling water, and detained therein for fome time, in order that the heat might penetrate 

 them thoroughly. The efFeft was, that the light became quickly extinft, and did not, as 

 before, re-appear on the following evening. 



The Light of Ghno-iuorms, 



Exper. 6. A dead fhining glow-worm was put upon two ounces of water, contained in 

 a wide- mouthed phial, at the temperature of 58°. The phial was then funk, about two 

 or three inches deep, in boiling-hot water ; and, as the heat communicated itfelf to the 

 contents of the phial, the light of the glow-worm became much more vivid. 



Exper. 7. Another lucid dead glow-worm was put into warm water, at 114°, to fee 

 if that degree of heat would extinguifh the light ; but, on the contrary, its glowing 

 property was augmented. All the water was then poured off, yet the infe£t continued to 

 (hine for fome length of time. 



Exper. 8. The effeft of tliat heat which is obtained from dry. folid bodies by fri£lion, 

 was next tried upon the light of the glow-worm. Two living glow-worms were put into 

 a one-ounce phial, with a glafs flopple ; and, though they were perfeftly dark at tke time, 

 yet, if the phial was brifkly rubbed with a filken or linen handkerchief, till it became 

 pretty warm, it fcldom failed to make them difplay their light very finely. This ex- 

 periment was very frequently repeated. It had the fame illuminating effcft upon the light 

 of a dead glow-worm. 



Exper. 9. The complete influence of 212 degrees of heat was now applied to the light 

 of a glow-worm, by pouring upon one when dead, but in a luminous flate, fome boiling 

 water. Its light was inftantly extinguifhed thereby, and did not revive. The ex- 

 periment was repeated, and with the fame rcfult. 



