586 PHILOSOPHICAL TRANSACTIONS. [ANNO I768. 



brightest parts; which, if good phosphorus, will be a white powder; and may be 

 preserved by keeping it in a dry phial with a ground stopple. 



The quantity of light a little of this phosphorus gives, when first brought 

 into a dark room, after it has been exposed for a few seconds, on the outside of 

 a window to the common light of the day, is sufficient to discover the time by a 

 watch, if the eyes have been shut, or in the dark, for 2 or 3 minutes before. 

 By this phosphorus celestial objects may be very well represented ; as Saturn and 

 his ring, the phases of the moon, &c. if the figures of them, made of wood, be 

 wetted with the white of an egg, and then covered with the phosphorus. And 

 these figures appear to be as strongly illuminated in the night, by the flash from 

 a near discharge of an electrified bottle, as by the light of the day. 



Exp. 1 . Having put some of the same parcel of the phosphorus into two glass 

 balls, and sealed them hermetically; he placed one of them on the outside of a 

 window facing the south, that it might be very much exposed to the direct rays 

 of the sun, where it remained from the 25th of December 1764, to the 25th of 

 December 1765. The other was kept during the same time in darkness. After 

 this, they were both exposed to the light, and carried into a dark room together ; 

 where the phosphorus in each appeared equally bright. 



Exp. 2. Some of the phosphorus finely powdered, being put into a glass ball, 

 with as much water as would make it adhere to the glass, so as to cover the in- 

 side of the ball, which was hermetically sealed, was found gradually to lose its 

 property of imbibing and emitting light, but faster in summer than in winter ; 

 so that at the end of the first year, it could not in the least be perceived to shine, 

 when taken from the strongest day light, and carried into a dark room. It was 

 also observed to lose its whiteness by degrees, and to become of a very dark 

 colour, especially on that side of it next to the glass. Some of the phosphorus 

 which was made to stick to the inside of a glass ball hermetically sealed, by means 

 of common spirit of wine, was found after one year to be a little impaired ; but 

 some made to stick by means of an aitherial spirit, was found not to be im- 

 paired at all. 



According to Dr. Nic. Lemery (in his Course of Chemistry, 11th edition) 

 the exposing the Bolognian stone to the sun wears it out. But by the first ex- 

 periment it appears, that a phosphorus of the same kind was not hurt by the sun 

 in 12 months. Water, indeed, in the 2d experiment, was found in that time to 

 destroy it. Therefore it is probable, that what the Dr. imputed to the light of 

 the sun, was caused by the moisture of the air. 



Exp. 3. Mr. C. mixed a small quantity of the phosphorus with a considerable 

 quantity of spirit of wine in one glass ball, and with aether in another, and sealed 

 them hermetically. When the balls were shaken, each of the fluids appeared 

 like milk; but the phosphorus would soon subside when the balls were at rest, 

 and leave the spirit of wine and aether quite clear. After some months the spirit 



