On the Light from organifed Bodies. 457 



Any of the faline Solutions mentioned in the fourth SeHion, being impregnated with luminous 

 Matter, and left fome Time at rejl, are rendered more lucid by a moderate Degree 

 of Heat. 



Exper. lo. A quantity of illuminated folution was depoCted in the laboratory. The 

 next evening, when it was examined, it appeared in a manner quite dark ; but, by putting 

 the phial which contained it into hot water, the light revived, and was foon rendered ex- 

 ceedingly vivid. 



Exper. II. About a pint of folution impregnated with light, had become obfcure, by 

 time and reft, as is the nature of this mixture. Such a quantity of boiling-hot water was 

 then added to it, as only to give it a fmall degree of warmth, and it quickly caufed it to 

 appear luminous. 



Exper. 12. Illuminated liquid, to the quantity of four ounces, was placed in the 

 laboratory until the next evening, when it had become almoft dark. One fpoonful of 

 boiling-hot water being put into it, the light re-appeared ; and, by means of two morfe, it 

 was rendered confiderably lucid. 



Their Light is extinguijhed by a great Degree of Heat. > 



Exper. 13. Some boiling water being poured upon three or four ounces of illuminated 

 liquid, In an earthen veflel, the light was immediately extingulfhed ; and, though after- 

 wards kept a confiderable time for infpeftion, and often agitated, to ftir up the hidden 

 light, yet no remains of any fliining property could be perceived. This experiment was 

 frequently repeated, and always with the fame refult. 



Exper, 14. Four ounces of very luminous liquid, together with a thermometer, were 

 put into a fmall earthen veflel, glazed white, the better to refleft light. Boiling-hot water 

 was then added, by fpoonfuls at a time, and by flow degrees. The firft few fpoonfuls 

 made it confiderably more lucid; and then, by adding more, the light began to fade, and 

 at length was gradually extinguifhed. This efFe£t took place, In one inftance, when the 

 liquid was heated to 96°; in another, to 98° ; and In a third, to 100°. Hence, this 

 fpecies of light, when thus united with water, feems to be extinguifhed at from 96 to 100 

 degrees of heat. This is a very elegant and pleafing method, of knowing how much heat 

 is required to extinguifli the light ; becaufe It meafures It exadlly, provided the hot water 

 be added in fmall quantities, and by flow degrees, as above diredled. To prevent the 

 poflfibility of any light reviving after an experiment of this kind, would require a much 

 greater heat than that of 100°. The Intention of the prefent experiment was only to 

 Ihow, that all light may be apparently extinguiflied, at fo low a degree of temperature as 

 from 96° to 100°. 



Exper. 15. A phial of an ounce and a half was filled with fome very luminous liquid, 

 but not corked. It was then fufpended by a firing, in a quart of boiling-hot water 



Vol. IV. — January 1801. . 3 N contained 



