2(52 



coarfe grained j 

 compofed nearly 

 like the others. 



It contained a 

 yellow tranfpa- 

 rent globule, 

 fofrerthancalca 

 reous fpar. 



Stone from Bo- 

 hemia. Com- 

 pofed like the 

 preceding } 



but its pyrites 

 very minute ; 

 the quantity of 

 metallic iron 

 much greater j 



ON STONY AND METALLINE SUBSTANCES 



all ftones of this kind. As the ftone was of a very fmall fize.^ 

 it became neceflary to facrifice the whole of it to the inveftn 

 gation of its nature. Its grain was coarfe, fimilar to that of the 

 flones from Benares: in it might be perceived the fame gray 

 globular bodies, the fame kind of martial pyrites, and the fame 

 particles of iron in the metallic flate. The proportion of thefe 

 laft: was much lefs than in the ftone from Yorkshire ; but 

 rather greater than in the ftones from Benares. The fame 

 kind of gray earthy fubftance ferved to connect the different 

 parts together; and nothing more could be perceived, except 

 a few globules, which confifted wholly of black oxide of iron, 

 attractable by the magnet, and one {ingle globule of another 

 fubftance, which appeared to differ from all thofe we have 

 • already defcribed. This laft fubftance had a perfectly vitreous 

 luftre, and was completely tranfparent : it was of a pale yellow 

 colour, flightly inclining to green; and its hardnefs was rather 

 inferior to that of calcareous fpar. The quantity of it, however, 

 was too fmall to be fubmitted to fuch an inveftigation as might 

 have determined its nature. The black cruft which covered 

 the ftone, was rather thinner than that of the ftones already 

 defcribed ; and feemed to have undergone a kind of contraction, 

 which had produced in it a number of fiflures or furrows, 

 thereby tracing upon the furface the appearance of compart- 

 ments, fimilar in fome meafure to what is obferved in thq 

 ftones called Septaria. 



The fpecific gravity of this ftone was 3-HS. 



STONE FROM BOHEMIA. 



The internal ftruclure of this ftone is very fimilar to that of 

 the ftone from Yorkshire. Its grain is finer than that of the 

 ftones from Benares : in it may be obferved the fame gray fub- 

 ftance, both in fmall globules and in particles of an irregular 

 fhape; alfo the fame particles of metallic iron. The fame kind 

 of earthy fubftance likewife ferved to connect the other parts 

 together. 



This ftone, however, differs materially from the others. 



Firft. The particles of pyrites cannot be (een without a lens. 



Secondly. It contains a much larger quantity of iron in the 

 metallic ftate ; infomuch, that the proportion of that metal, 

 feparated from it by means of the magnet, amounted to about 



1$ 



To-5 



of the weight of the whole. 



This 



