on the Production of Light from Bodies. 
33 
Sea coal. 
White paper, 
— linen, 
woollen. 
in small pieces. 
hair powder. 
Deal sawdust. 
Rotten wood (not otherwise luminous). 
White asbestos. 
Red irony mica. 
Deep red porcelain. 
6. Antimony, nickel. 
Oils, lamp, linseed, and olive, 
White wax, 
Spermaceti, 
Butter, J 
] 
r 
luminous at and below 
boiling. 
The duration of the light thus produced from different bo- 
dies is very unequal ; in some the light is almost momentary, 
in others it lasts for some minutes, and may be prolonged by 
stirring the powder on the heater. It soon attains its greatest 
brightness, and dies away gradually from that point, never 
appearing in a sudden flash, like the light of quartz pebbles 
rubbed together. If blown upon, it is suddenly extinguished, 
but immediately re-appears on discontinuing the blast. 
The light of bodies is, in general, uncoloured ; there are, 
however, some exceptions. Blue fluor, of that kind which 
gives out a fetid smell when rubbed, first emits a bright 
green light, resembling that of the glow-worm so exactly, 
that when placed by the insect just as it has attained its 
greatest brightness, there is no sensible difference in the two 
lights, either of colour or intensity. This bright green quickly 
MDCCXCII. F 
