Dr Brewster on the Phosphorescence of Minerals, 885 
Having had occasion to examine the nature of the light emit- 
ted by phosphorescent bodies, I was led to attend to a subject 
which I had Considered as exhausted by the observations of 
Haiiy ; but having seen indications of phosphorescence in sub- 
stances which were not contained in his list, I resolved to repeat 
his experiments, and to examine every mineral which I could 
readily command. 
In making these experiments, I never reduced the body to 
powder, but always placed a fragment of it upon a thick mass 
of hot iron, carried into a dark room. When the phosphores- 
cence was not readily perceived by this method, I took a pistol 
barrel, and having shut up the touch-hole, I introduced the mi- 
neral into the breach, and placed the bottom of the barrel in the 
fire. Before a red heat was produced, the phosphorescence was 
distinctly seen by looking into the barrel, which I sometimes did 
through a plate of glass, to keep the heated air from the eye, 
and sometimes through a small telescope, adjusted to distinct 
vision at the bottom of the barrel. At other times the mineral 
was not introduced into the barrel till it was taken out of the 
fire, and till the red heat had entirely disappeared. 
In this way, I obtained the following results. 
TABLE of Phosphorescent Minerals. 
Colour of the 
Colour and Intensity of their 
Names of the Minerals. 
Minerals. 
Light. 
Fluor spar 
Pink 
Green 
Purple 
Bluish 
Bluish-white 
Blue 
Compact fluor 
Yellowish 
Fine Green 
5 Sandy fluor 
White 
White sparks 
Calcareous spar 
Yellow 
Yellow 
Transparent 
Yellowish 
Limestone from North of 
Ireland 
Yellowish-red 
Phosphate of lime 
Pink 
Yellow 
10 Arragonite 
Dirty white 
Reddish-yellow 
Carbonate of barytes 
Whitish 
Pale white 
Harmotome 
Colourless 
Reddish-yellow 
Dipyre 
White 
Specks of light 
Grammatite from Glentilt 
Yellow 
15 Cornwall 
Bluish 
Topaz, Aberdeenshire 
Blue 
Bluish 
Brazilian 
Yellow 
Faint yellowish 
New Holland 
White 
Bluish 
Rubellite 
Reddish 
Scarlet 
20 Sulphate of lime 
Yellowish 
Faint light 
barytes 
Yellow 
Pale light 
Slate colour 
Pale light 
