34 PHOSPHORESCENCE 



bles of air or oxygen are passed into the gas ex- 

 perimented with. Carburetted hydrogen did not give 

 the same result. This deserves to be examined 

 anew, for I have shown in my ( Recherches nouvelles 

 sur le Phosphore/ that phosphorus is not volatile 

 at the ordinary temperature of the atmosphere. 



According to Fischer, phosphorus is luminous 

 in the atmosphere at any temperature above zero 

 (freezing-point) ; it is even luminous at 6 (centi- 

 grade), but does not then appear covered with va- 

 pours. At a lower temperature its light disappears 

 completely. In the barometric vacuum no light 

 is produced by phosphorus. (See Fischer, " On 

 the Light of Phosphorus," in ' Journal fur prak- 

 tische Chemie/ t. xxxv. p. 342.) 



It is not true that phosphorus becomes lu- 

 minous in carbonic acid, carbonic oxide, oxide of 

 nitrogen, and cyanogen, as some have asserted. 

 When such appears to happen, the gases are 

 found to contain small quantities of air. The 

 smallest quantity of air is indeed sufficient to oc- 

 casion a production of light in these circumstances. 



A solution of phosphorus in spirit of wine is 

 luminous when dropped into water ; the light is 

 only perceived where the drops fall into the liquid. 

 One part of phosphorus communicates this pro- 

 perty to 600,000 parts of spirit of wine. 



Water in which phosphorus is preserved, be- 

 comes luminous in the dark after a certain time. 



