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 lumimous 
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 lght 
is produced by phosphorus. (See Fischer, ‘ On 
the Light of Phosphorus,” in ‘Journal fiir 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 contam 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 im 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. 
