I 



THE BOTALLACK MINE. 291 



worked in those parts, where it is rendered rich by the junction with 

 veins ; the small veins are also worked for ore, and are very pro- 

 ductive. The rock is what is called a free or soft killas, near the 

 great cross course or vein ; but further from it, it becomes a hard 

 blue elvan {flinty slate.) The width of the vein varies from nine 

 to twelve feet. It contains grey copper ore of a rich quality. Some- 

 times the sides of the vein are copper ore, and the middle is tin ore, 

 as represented Plate VII. fig. 7. c c, which is a vertical section of 

 part of the vein ; fig. 6. is a horizontal section of the cross course 

 and veins. The master of the mine furnished me with the above 

 particulars; and under his direction, I made, on the spot, the two 

 rough sections, which will serve to convey a better notion of this 

 singular metallic repository, than can be obtained by verbal descrip- 

 tion. 



Nor should it be omitted, that the entrance of this mine is at the 

 foot of a precipice more than 200 feet in height, on the border of the 

 • Adantic Ocean, and the workings of the mine extend two hundred 

 and thirty yards under the sea. From this submarine recess I saw 

 rise up, one of the best-formed and noblest-looking men I ever be- 

 held, — a perfect model for the Apollo of a sculptor. 



Parucular metallic ores are peculiar to certain rocks. Thus, tin 

 ore occurs in granite and some kinds of slate, but has never been 

 found in limestone. Certain ores are not unfrequently associated 

 together : thus, lead and zinc often occur in the same vein, but in 

 different proportions. The same metal in various combinations is 

 often found in one vein : thus, native copper, sulphuret of copper, 

 carbonate of copper or malachite, sulphate of copper or blue vitriol, 

 and copper combined with lead and iron, frequently occur together 

 in the same mine. 



Galena, a sulphuret of lead, is often associated with white lead 

 ore, or carbonate of lead. The latter, though a rich ore containing 

 seventy per cent, of lead, has no metallic appearance, and was mis- 

 taken for cawk, and thrown away, by the miners in Derbyshire, un- 

 til the year 1803 or 1804. The mines of that county have been 

 worked ever since the time of the Emperor Adrian, and the quantity 

 of ore which has been wasted during that period must have been im- 

 mense.* 



* In 1810, few of the working miners could distinguish compact white lead ore, 

 from cawk or sulphate of barytes ; their specific gravity and appearance are not 

 very different. The following lest is of easy application, and will serve to dis- 

 cover the presence of lead : — If a small quantity of flowers of sulphur, mixed with 

 a little potash or soda, be melted on the point of a knife, in a candle, and applied 

 to the moistened surface of the stone, it will make a black spot if the mineral con- 

 tains white lead ore. 



The native carbonate of lead readily dissolves in dilute nitric acid, with effer- 

 vescence, and it promptly yields metallic lead under the blowpipe on charcoal. — 

 B. S. 



