On Light. 17 
to the sun, whose beams are supposed to penetrate, and combine 
with, the different forms of terrestrial matter. But we learn from 
Seripture, that light pre-existed before this luminary, and that 
its subsequent condensation in his orb, was a particular act of 
Almighty Power. The phosphorescence of minerals, buried since 
the origin of things in the bowels of the earth, coincides strictly 
with the Mosaic account of the creation. We shall therefore re- 
gard light, the first-born element of Chaos, as an independent 
essence, universally distributed through the mineral, vegetable, 
and animal world, capable of being disengaged from its latent 
state by various natural and artificial operations. These are 
1. Friction. 
To this head belong electrical light, and that evolved from 
the attrition of pieces of quartz, even under water. 
2. Condensation and expansion. If atmospheric air or oxy- 
gen be suddenly compressed in a glass syringe, or if a glass ball, 
filled with the latter, be suddenly broke im vacuo, a flash of light 
is instantly perceived. 
3. Heat.. If air which has been heated up to 900° of Fahren., 
and which is in itself obscure, be made to fall on pieces of me- 
tal, earth, &c. it will speedily communicate to them the power of 
radiating light. The brilliant flame exhibited in the burning of 
charcoal and phosphorus, is shown, in the article ComBustion, 
to be merely the ignition of the solid particles of these bodies. 
At a certain elevation of temperature, about 800° Fahr., all solid 
bodies begin to give out light. The same effect is produced im 
vacuo by transmitting voltaic electricity through a metallic wire, 
To this section, we must also refer the phosphorescence of mi- 
nerals. This curious phenomenon seems to have been first de- 
scribed by Benvenuto Cellini, in his Treatise on Jewellery, pub- 
lished near the beginning of the 16th century. In the year 1663, 
Mr. Boyle observed, that diamond, when slightly heated, rubbed, 
or compressed, emitted a light almost equal to that of the glow- 
worm. 
The most complete account which we have of mineral phos- 
phorescence, is that recently given by Dr. Brewster in the first 
volume of the Edinburgh Phil. Journal. ‘His method of exami- 
nation was ingenious and accurate. He never reduced the body 
to powder, but placed a fragment of it upon a thick mass of hot 
iron, or, in delicate experiments, introduced it into the bottom 
of a pistol barrel, heated a little below redness. 
The following Table presents his Results: 
Vol. 58. No, 279. July 1821. CG Names 
