CLASS IV. 
METALLIC SUBSTANCES. 
225. OF METALS IN GENERAL. 
METALS, in a perfect state, are easily distinguished from 
other minerals, by a peculiar brilliancy which pervades their 
whole substance, and which has the name of metallic lustre ; 
by their complete opacity, and their great weight in propor- 
tion to that of other mineral substances. 
When taken from the earth they are found in one or other 
of the four following states : 1. In a native or metallic state. 
2. Combined "with sulphur. 3. In a state of oxide (21). 
4. Combined with acid. 
Metals, when found in a state of combination with 
other substances, have the name of ores. They are in 
general deposited in veins (4<), of various thickness, 
and at various depths in the earth. The mode of ob- 
taining them is to penetrate from the surface of the 
earth to the vein, and there to follow it, in whatever 
direction it may lie. The hollow places thus formed 
are called mines, and the men employed in them are 
denominated miners. When the veins are at a great 
depth, or extend to any considerable distance beneath 
the surface of the earth, it is necessary, at intervals, to 
make openings, or shafts, to the surface, for the ad- 
mission and circulation of the air ; and also to draw off 
the water which collects at the bottom, by drains, 
pumps, or steam-engines, as the situation or circum- 
stances require. 
After the metallic ores are drawn from the mine, 
they, in general, go through several processes before 
they are in a state fit for use. Some of them are first 
washed in running water, to clear them from earthy 
