424 Dr. Hulme’s Experiments and Observations 
III. The imbibed Light , after being in a latent State , (s excited 
and rendered luminous by the Agency of Heat. 
Exper. 7. Some small pieces of the phosphorus, after having 
been illuminated, were deposited in the laboratory ; when the 
light by degrees faded away, and became totally invisible. They 
were kept in this dark state for the space of ten days, and then 
placed one after another upon a heated bar of iron, as in the 
last experiment, upon which they quickly became exceedingly 
luminous. 
From an experiment made by the ingenious Mr. Canton, 
I observe, that some of his phosphorus, contained in glass 
balls hermetically sealed, and heated in the above manner, gave 
a considerable degree of light, after it had been kept in a state 
of darkness more than six months. Phil. Trans. Vol. LVIII. 
page 342. 
§ it* 
The Effects of Cold on imbibed Light. 
EXPERIMENT. 
About 15 grains of the phosphorus were put into a half- 
ounce phial, containing two drams of cold pump water, that had 
been deprived of its air by boiling. The phial was then corked, 
and exposed for some time to solar light, whereby the phosphorus 
became finely illuminated. In this state, it was immediately put 
into a frigorific mixture, composed of snow and sea-salt, and 
retained there about 30 or 40 minutes, when it was taken out, 
and the light found to be totally extinguished. The phial was 
then placed in some water, at about 6 o° temperature, and the 
