Ses * 
+ 
Rotten- Stone. 323 
men at Ashford, as being less fit for their 
purpose than that I have just described—It 
appears to be too soft to receive a lasting 
polish, and its colour, though black, is much 
less deep than in the foregoing variety, fre- 
quently verging on brownish-black :—texture 
earthy: fracture slaty : hardness 6: gives out 
a very fetid smell on being scraped. One 
specimen of this stone contained, according 
to the experiments made on it, 66 carbonate 
of lime; 24 alumine ; 1,2 oxide of iron; 1,5 
silex ; and 7 inflammable matter. Anotler 
specimen of this stone, however, from the 
same bed, yielded only 19 alumine. 
A third strongly marked variety of lime- 
stone, found with the foregoing, has the follow- 
ing characters: colour black, or brownish- 
black : texture splintery, with disseminated, 
shining, spar-like particles ; these frequently 
exhibit the minute parts of organic remains: 
fracture slaty : hardness 7: emits a very fetid 
odour, when scraped or rubbed. “’I'he speci- 
men analyzed gave 8 per ct. alumine, and 4 
silex, with 7 inflammable matter, but little or 
no trace of iron. 
It must now be observed, that, along with 
these three described varieties of limestone, 
several others occur, which, in their eaternal 
characters, exhibit various gradations between 
ss2 
