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which constitutes the martial vitriol, found to be near 
the one eighth part of this cinder-like matter. 
When the cliffs were obferved to burn in the 
night-time, the flame was plainly perceived by a 
Spectator at a didance ; but, when he drew near to 
the place, feemingly on fire, he could perceive a 
fmoke, but no flame. In the day-time, nothing but 
a fmoke was perceived, except the fun Shined, when 
the cliffs appeared, at a didance, as if they were co- 
vered with pieces of glafs, which reflected the fun’s 
meridional rays; but, upon drawing near to the 
places, where thefe luminous appearances were per- 
ceived, they difappeared, and the cliffs feemed to be 
covered with fmoke, which dunk of a bituminous 
and fulphureous matter. 
I have alfo been an eye-witnefs of the fame kind 
of flame arifing from the Lodes in Cornwall, cfpe- 
cially fuch, as contained a great quantity of mundic 
and martial pyrites. Three times I have feen this 
flame arife from the earth in the night, and once in 
the middle of the day. In the night, a perfon, 
danding at a little didance, would imagine, that the 
place was all on fire, and even on drawing near the 
fame, he perceives himfelf Surrounded with flame, 
but is not hurt ; and in four or five minutes time, he 
perceives this flame to decreafe, and fall into the 
earth. In the day-time, the flame is of a different 
colour, and not much unlike the flame, which ariles 
from a furnace. There are feveral mines difcovered 
in this county by thefe mineral fires, where there 
were no fymptoms of fuch mines before : but it is 
generally obferved, that they abound with mareafite 
and pyrites. Moreover, thefe mineral flames, arifing 
Vol, LII. R from 
