J^O On Stones chferved to fall from the Clouds. 



and fulphuric gafes, containing the generic principles of iron, 

 magnciia, and nickel, Sec. : thefe, uniting with filiceous, ar- 

 gillaceous and calcareous earths, produce in great quantities 

 that fpecies of iron ore termed bog ore, and that in much 

 greater quantities than is generally in)agined. '1 hefe ores are 

 produced in Kmips from 40 to 100 lbs. and more in weight, 

 containing from one-fourth to one-half of pure metallic iron, 

 intermixed with pyrites and vitrified fnbliances refembling 

 elafs and petrified fhells, the inhabitants of frefli-water lakes. 

 Whence it is evident that a number of petrifafliions and mi- 

 neralizations are performed by water and air aOifted by the 

 electric fluid alone ; and a number of the operations of nature 

 have been attributed by philofophers to the cfl'etfls of fire, and 

 deemed volcanic, which are the efi"e£ts of the aqueous and 

 pneumatic elements. 



In order to afcertain in fome refpefts the truth of this 

 propofition by experiment, I caufed a quantity of gas, libe- 

 rated from water by means of Heel filings and vitriolic acid, 

 to be received in a glafs vefl!el, to which was added carbonic 

 acid from the fumes of charcoal and fulphuric gas, with the 

 fine duft of chalk and earth, until the whole appeared a dark 

 thick cloud. The eleftric fpark being then palled through 

 it, a flafli of light and a fmart detonation enfued. After this 

 operation the cloud became more tranfparent, leaving at the 

 bottom of the veffel a quantity of water, with a gray powder, 

 evidently metallic, mixed with earth. If the experiment had 

 been performed on a larger fcalc, and the ingredients varied, 

 the refult might have been more decided, and the phicnome- 

 iion more accurately demonftrated. 



This is a fubje6l that merits every philofophic inveftiga- 

 tion. The magnitude of the ftones undoubtedly depends 

 on the quantity of generating matter, and the height from 

 whence it falls; yet, how ftones of fuch a wt-ight as that 

 which fell in Yorkfliire could be formed in the air, might be 

 a fubjecl of doubt, if the fubftance had not been found of the 

 fame nature as thofe which fell in Bohemia and Sienna. But 

 it ought to be confidered that thefe fubftances are not formed 

 inflantaneous in the clouds: the conftituting matter, pre- 

 cipitated by the eleftric fliock, is thrown by the explofioa 

 to a point, when, from the action of the air in falling, it 

 becomes enveloped in the terra cementium with which the 

 matter is mixed. Whence, the greater the height or range 

 the matter has to pafs through from the time of the eleclric 

 (hock, the larger will be the (tones. Molt if not all the 

 meteors formed in the air even at great heights probably 

 originate from one caufe : thofe which contain the larger 



portioa 



