22 EYE SPY 



with animal life, which, though dwelling in depths 

 scarce reached by the faintest gleam from the sun, 

 swim about enveloped in their self-illumined halo. 



While all these phenomena come under the 

 general term of phosphorescence, the inference of 

 the presence of phosphorus is incorrect; many 

 substances without a trace of phosphorus in their 

 constitution emit light with equal brilliancy. 



The well-known commercial article called "lu- 

 minous paint " is an apt example, which, while 

 containing no trace of phosphorus, glows like fox- 

 fire at night, especially after having been exposed 

 to the sun's rays during the day, giving forth in 

 the dark hours the light which it has thus ab- 

 sorbed, and being thus of utility in its application 

 to clock faces and match-boxes. 



Calcined lime and burnt oyster-shells, in com- 

 bination with certain acids, become luminous at 

 night by the similar power of absorption and 

 transmission of light vibration which is supposed 

 to be the secret of much of the so-called phos- 

 phorescence. 



But fox-fire is believed to be of a different 

 nature, more chemical in its character, and usu- 

 ally emanates from a fungus, either visible in the 

 form of mould or toadstool, or existing as an al- 

 most invisible essence which saturates the decaying 

 wood, a species known as Thelaphora cerulea being 

 credited with most of the luminous manifestations. 



