B16 Cursory Remarks on 
ence; texture, earthy; fracture, sometimes 
imperfectly conchoidal; at other times slaty; 
hardness, from that of chalk to that, which 
does but just yield to the scraping of the knife 
(3—6. Kirwan.); feels smooth, sometimes 
rather greasy—never so meagre as the foreign 
tripoli ; does not. crumble soon in water ; 
eflervesces slightly with acids; sp. gr. 2,3, 
Lis colour is usually between a brownish grey 
and isahella-yellow.—The other variety occurs 
in a loose or pulverulent form ; feels meagre ; 
rarely effervesces with acids; sp. gr. 2,2; its 
colour ight yellowish-grey. 
5. The kard Rotten-stone (as the indurated 
kind is called by the Rotten-stone geééers) 
occurs in detached, nodular lumps, dispersed 
through the rubble above noticed ;—the soft,* 
as a spongy earth or mud, either coating the 
more indurated variety, or deposited, in con- 
siderable quantities, under the debris, on the 
surface of the limestone rock. 
6. Water, from the upper part of the moor, 
is constantly draining through the loose mate- 
rials, which fill the hollows and fissures of the 
rotten-stone tract. 
7. In this mineral depot are found, with the 
Rotten-stone, fragments of chert; fragments 
of a calcareous stone in every possible state, 
* Vide Note D. 
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