166 Fossils. 



respect, a remarkable difference among 

 themselves. They are completely opaque. 

 They also possess a mirror-like lustre, 

 which is one of their characteristic marks 

 and they present a convex surface when 

 melted in earthen vessels. Besides, they 

 are all insoluble in water. And by these 

 external characters, it is easy to distin- 

 guish this class from all other fossils, viz. 

 earths, salts, bitumens, and sulphur. 



Metals are concealed in the earth, and 

 form ores, which existing in crevices of 

 rocks, are called ^Z72,9,and are distinguish- 

 ed into level, or into inclined, direct or 

 oblique, according to the angle they make 

 with the horizon. The part of the rock 

 resting on the vein, is termed, the roof; 

 and that on which the vein rests, the bed of 

 the vein. And the cavites made in the 

 earth, in order to extract these ores, are 

 called mines. 



When nature has bestowed on metals 

 their proper metallic appearance, or they 

 are only alloyed with other metals, they 

 are said to be native. When combined, 

 as they commonly are in mines, with some 

 unmetallic substance, thev are said to be 

 mineralized ; the substance that sets them 



