344 Singular luminous property of Wood^ 4'c. 
capable of being developed by the heat of the flame of a candle, 
might have some useful application. In order to obtain some 
information on this point, ,I prepared three or four pieces of 
wood terminated with the white masses of absorbed lime, and 
placed these masses so as to remain near the circumference of 
the flame of a candle. In this situation they yielded the bril- 
liant light already described, and lasted, without any apparent 
diminution, for more than two hours. I next prepared a very thin 
slice of chalk, and having held it in the flame of the candle, I 
found that it did not give the same brillia!nt light as the ab- 
sorbed lime. Upon exposing it, however, to the heat of the 
blowpipe, it emitted the same white and dazzling light whicii 
has already been described. 
In order to observe if the minute particles of the lime and tlie 
magnesia would remain in the pores of TahasJieer^ and give out 
their light when laid upon a hot iron, I took two pieces of Ta- 
basheer, and having discharged their natural phosphorescence, 
by exposing them to a high degree of heat, I placed one of them 
in lime-water, and the other in a solution of sulphate of mag- 
nesia. When the pieces of Tabasheer were dry, I then put 
them upon a hot iron, and found that the piece which had been 
placed in the lime-water was considerably phosphorescent, while 
that which was immersed in the magnesian solution discharged 
no light at all. 
As this light seems to be developed by degrees of heat in- 
versely proportional to the minute state of division in which 
the particles of lime are combined ; it is highly probable, that 
denser kinds of wood, in which the pores are very small, might 
leave, after combustion, a residue in which the lime exists in a 
much more attenuated state than that which I used, and there- 
fore the same intensity of light might be evolved at a tempera- 
ture still lower than that which exists at the edge of a common 
flame. If this should turn out to be the case, the light of the 
lime and the magnesia might be developed at a temperature 
lower than that which discharges the phosphorescent light of 
minerals, and it might have a most extensive and useful ap- 
plication, both in the arts and in domestic economy. Even in 
the present state of the fact, the subject deserves farther inves- 
tigation. . . 1). B. 
Edinscrgh, Jfdfj 18^0. 
