154, ••**' S'rONY AND METALLINE SUBSTANCES 



approach ftill more nearly to each other, fo as abfolutely to 

 come into contact, and in that manner to form a kind of chain, 

 folded upon itfelf in the interior part of the fubftance, and 

 leaving a great number of cavities between the links of the 

 chain fo folded. Let us then fuppofe, that the earthy fub- 

 ftance with which thefe cavities are filled, being very porous, 

 and having but a fmall degree of. confidence, fhould (as may 

 happen by a variety of caufes) bedeftroyed. It is plain, that 

 if fuch a deftru&ion were to take place, the iron alone would 

 remain ; and, being thus left bare, it would appear in the 

 form of a mafs, more or lefs confiderable, of a cellular texture, 

 and as it were ramified ; fuch a form, in thort, as that in 

 which moft of the native irons we are acquainted with have 

 been found. May it not be fair to attribute to fuch an origin, 

 the native iron found in Bohemia, a fpecimen of which was 

 prefented by the Academy of Freyberg to Baron Born, and 

 which came, with the reft of his collection, into the hands of 

 Mr. Greville ? May not fuch alfo, notwithstanding the enor- 

 mity of its bulk, be the origin of the mafs of native iron found 

 in Siberia, near Mount Kemirs, by the celebrated Pallas ? 



We have already feen, in the refults of the analyfes made 

 by Mr. Howard, of the various ftones above defcribed, that 

 he conftantly found a certain proportion of nickel mixed with 

 the iron they contained. This circumftance recals to our no- 

 tice the obfervations that were made by Mr. Prouft, fome time 

 ago, refpecting the mixture of nickel in the native iron of 

 South America ; and tends to give fome additional fupport to 

 the opinion hinted at in the foregoing paragraph. 



The circumftances juft mentioned, naturally gave to Mr. 

 Howard, as well as to me, a defire to know whether the 

 native iron from Siberia, and that from Bohemia, were alfo 

 mixed with nickel. Mr. Howard, confequently, loft no time 

 in proceeding upon this important inveftigation. The native 

 iron of Siberia prcfents fome very interefting peculiarities, 

 and has often been referred to, but has not yet been properly 

 defcribed ; it is therefore with great pleafure that I add the 

 following defcription of it, and of fome other kinds of native 

 iron, to the defcription I have already given of the various 

 ftones faid to have fallen on the earth. 

 The Siberian I feel the greater fatisfacVion in doing this, as the noble col- 



native h-on j lection of Mr. Greville contains two fpecimens of this iron, in 



perfect 



The ftones exa> 

 mined by Mr. 

 Howard con- 

 tained nickel, 



and fo do the 

 S. American 



iron. 



