OBSERVATIONS ON SPONTANEOUS LIGHT. 105 



Exp. 2. Some fragments of this illuminated phofphorus 

 were put into a fmall phial, which was then doled with a cork, 

 and fufpended, by a ftring, in a quart of water heated to about 

 ] 26° ; by thefe means, the light was rendered much more vivid 

 than before. 



Exp. 3. Some other pieces of the illuminated phofphorus 

 were dropped feparately into a glafs tube 32 inches long, and 

 T 7 ^ bore, filled with water at about 120°. The light of each 

 piece became exceedingly bright, as foon as it entered the hot 

 water ; and they all defcended, very luminous, from the top 

 to the bottom, fome quickly and others flowly, according to 

 their gravity, making a very pleafing experiment. 



Exp. 4. A large wooden bowl, about 12 inches wide, was 

 next filled with water heated to abput 110°, and then a quan- 

 tity of illuminated phofphorus, partly in the form of powder, 

 and partly in pieces of different magnitudes, was fcattered 

 over the whole furface of the water ; all which pieces fell, 

 with increafed fplendour, to the bottom, where they preferved 

 their light for fome time, 



II. The imbibed Light is extiriguijtod by a great Degree of Heat, but too much 



heat extinguish. 

 Exp. 5. Some fragments of the phofphorus, rendered lumi-es it. 



nous, were expofed to a greater degree of heat, namely, by 

 cafting them into a tin veiTel containing two pints of boiling 

 water. They flamed with increafed light, as foon as they 

 came in contact with the water, fell precipitately to the bot- 

 tom, in a lucid ftate, and then were gradually extinguifhed. 



Exp. 6. In which the degree of heat was fiill increafed. A 

 fmall bar of iron, of about an inch fquare, was made red-hot, 

 and laid horizontally in the laboratory, until, by cooling, it 

 nearly ceafed to mine. Some pieces of illuminated phofpho- 

 rus were then put upon it in fucceffion, and the light, in a mo- 

 ment, glowed with uncommon luftre, but was quickly after 

 totally extinguifhed *. 



* Solar light, when received merely on a piece of white paper, 

 may alfobe rendered more luminous by heat, and then extinguished 

 by it, as appears from an experiment made by the late Mr. §. 

 Wilfon, whofe book on phofphori I had not feen before thrs Paper 

 was drawn up. 



