380 
is an error in any author to place it indiscriminately with 
Tripoli; at least with that from Tripoli, which is sold in 
the shops for polishing (chiefly metals) ; and being now 
rare, they recommend Rotten Stone and Crocus Martis*, 
&c., for those purposes; although neither the Tripoli nor 
the Crocus Martis would at all suit the true lapidary. 
The upper specimen is part of an irregular flattish frag- 
ment of a lightish colour, begining to decompose. The 
middle figure is part of a nodule decomposing on the out- 
side: the curved line in the middle is part of a petrified 
shell, which is composed of Carbonate of Lime. The 
darker part is hard, looking like black Limestone (and 
much resembles the black Calp of the Irish, having also a 
similar foetid odour, quite offensive when scraped) ; but that 
is of a texture more durable, else it would not be used for 
tombstones and paving. 
The lower specimen is probably altogether Rotten Stone, 
or wholly decomposed rock, although it cannot be posi- 
tively known by outward aspect, as even the best lapidaries 
have experienced. 
Mr. Richard Phillips has analysed the Rotten Stone, and 
kindly favoured us with the result, as under; 
‘Alomine: 6) 600 bo aeeoesb 
Silicared. . £5) dee 
Carbonaceous matter’. 10 
Tripoli is said to contain 
SUDA. 4) ag OD 
miumine ':. « - owe 
QOxideoflron .. 2° 3 
although the Alumine and Iron are in general in greater 
proportion. 
* A rust of Iron, now often called Tripoli; rendering the true Tripoli 
more obscure. 
