T40 Experiments and Ohfervatlons 



proportion of thefe laft was much lefs than in the ftone from 

 Yorkfhire, but rather greater than in the ftones from Be- 

 nares. The fame kind of grav earthy fubftance ferved to 

 connect the different parts together; and nothing more could 

 be perceived, except a few globules, which confided wholly 

 of black oxide of iron, attractable by the magnet, and one 

 finale globule of another fubftance, which appeared to differ 

 from all thofe we have already defcribed. This laft fubftance 

 had a perfectly vitreous luftrc, and was completely tranfpa- 

 rent : it was of a pale yellow colour, (lightly inclining to 

 green ; and its hardnefs wa» rather inferior to that of calca- 

 reous fpar. The quantity of it, however, was too fmall to 

 be fnbmitted to fuch an investigation as might have deter- 

 mined its nature. The black cruft which covered the ft one 

 was rather thinner than that of the ftones already defcribed ; 

 and feemed tohave undergone a kind of contraction, which had 

 produced in it a number of fiffures or furrows, thereby tracing 

 upon the furface the appearance of compartments, fimilar in 

 fome meafure to what is obferved in the ftones called/^/aritf. 

 The fpecine gravity of this ftone was 3418. 



Sto?ie from Bohemia, 



The internal ftruclure of this ftone is very fimilar to that 

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

 the ftones from Benares : in it mav be ob ferved the fame gray 

 fubftance, both in fmall globules and in particles of an irre- 

 gular (hape; 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 feen without a lens. 



Secondly, It contains a much larger quantity of iron in 

 the metallic ftate ; infomuch, that the proportion of that 

 metal, fepa rated from it bv means of the magnet, amounted 

 to about -jV-oths of the weight of the whole. 



This (tone has alfo (owing, perhaps, to its having remained 

 a much longer time in the earth than the preceding ones, all 

 of which were taken up nearly at the very inftant of their 

 fall,) another difference, viz. many of the particles of iron 

 in a metallic ftate have undergone an oxidizement at their 

 furface; a circuuiftance that has produced a great number of 

 fpots of a yellowifh brown colour, and very near to each 

 other, over a part of its internal fubftance. This oxidize- 

 ment, by adding to the bulk, and to the force of action, of 

 the part we have defcribed as ferving by way of cement to 

 4 the 



