Page:Proceedings of the Royal Society of London Vol 1.djvu/295

Rh 4thly. That charcoal is not an oxide of carbon ; since, when rightly prepared, it requires quite as much oxygen for its combustion as diamond.

And lastly, That the diamond diﬂ'ers from charcoal, solely in the ﬁrmness of its aggregation, which is generally known to be an ob- stacle to every chemical change.

Mr. Davies Giddy communicated a letter from Mr. Joseph Came, giving an account of the Relistian Mine in Cornwall, in which rounded pebbles were found at the depth of seventy-ﬁve fathoms from the surface. The description is accompanied with a section of the mine, and plan of the lode.

The lode has been seen at various depths, from twelve to ninety fathoms, but its width then diminishes rapidly toward the east, but more gradually toward the west. The substances not metallic are schist, chlorite, and quartz. There is an engine-shaft at eight fathoms from the lode, on the north side from which levels are driven to the lode in the direction of a ﬂucan, or cross lode, which cut the main lode nearly at 45° from N.W. to S.E. The distance, in this oblique direction, is about ﬁfteen fathoms; for the ﬁrst ten fathoms there was only one ﬂucan, of four inches width. Then it became divided into four parts, so much divergent from each other, that at the depth of seventy-ﬁve fathoms the extreme branches extended twelve feet in width; where the ﬂucan reached the lode at this depth, there was ﬁrst discovered a little copper, and then a body of pebbles, the section of which was about twelve feet square. In this part of the lode the schist greatly predominates; of course (says Mr. Game) the pebbles are schistose, cemented in some par-Is by chlorite, in others by oxide of tin, which is generally crystallized, and in some of the crevices there is a little copper pyrites. The pebbles did not continue in a body to the height of more than two fathoms; but scattered bunches Were found four fathoms above, and six fathoms below the place where they were ﬁrst discovered.

At the depth of sixty-ﬁve fathoms, and in the lode adjacent to the ﬂucnn, on each side, had been found also a great number of schistose stones; but these were angular fragments, not rounded; nor was there any tin in or about them.

This analysis is preceded by a short abstract of the notice taken of the Dead Sea by various ancient authors, by Strabo, by Tacitus,