en certain Slony and Metalline Sidjiances. 53 



the tranfparent fubftancc, and the great refiftance we experi- 

 ence when we attempt to feparate them, we cannot help being 

 furprifed, that ahiioll all the fpeciniens of this mal's of me- 

 tallic iron that have been brought to Europe are in the cel- 

 lular ftatc already defcribed, owing apparently to the total, or 

 almofi: total, dellruftion of the tranfparent fubftance. But, 

 befides the frao;ilitv of this fubftance, the fpecimen in queftion 

 helps verv much to explain the above circumthince, inafmuch 

 as manv of the nodules of the tranfparent fubftance belong- 

 ing to it are in a ftate of real decompofition. In that ftate, 

 they are changed into a white opaque fubftance, which, upon 

 being lightly prefted or fqueezcd between the fingers, crum- 

 bles into a gritty dry powder. This decompofition may be 

 obferved to have taken place in various degrees : in many of 

 the nodules, the fubftance is merely become friable, without 

 being much altered in its appearance; whereas, fome of thofe 

 which are in a ftate of complete decompofition are of an 

 f)chreous reddifti yellow colour : it is, however, eafy to di- 

 Ilinguifti that this colour docs not belong to them, but is 

 owing only to the oxidizement of the adjacent particles of 

 iron. 



From the above obfervations it will not be difficult to con- 

 ceive the poffibility of the total, or nearly total, dcltruiSlion of 

 the tranfparent fubftance ; and alfo, the appearance the pieces 

 of iron muft naturally prefent when deprived of it. I cannot 

 help obfcrving likcwife, that there appears to exift a very in- 

 terefting analogy between thefe tranfparent nodules and the 

 globules I defcribed as making part of the ftoncs faid to have 

 fallen on the earth. This analogy, though not a very ftrong 

 one, may lead us to fuppofe that the twofubftances are fimilar 

 in their nature, but that the globules are lefs pure, and con- 

 tain a greater quantity of iron. 



The native iron from Bohemia is a compaft mafs, fimilar 

 to the compaft part of the large fpecimen of iron from Siberia, 

 which has Juft been defcribed : like that, alfo, it contains a 

 number of globular bodies or nodules; but they are not in 

 fuch great proportion as in the Siberian iron. They arc be- 

 fidts perfectly opa(]ue, and very much refemble the moll 

 compatl of the globiilcs belonging to the ftoues laid to have 

 fallen on the cardj. 



'Examination of the Iron from South America, 



T have already obferved, that my experiments coinridcc^ 



u-ith ihofe of Mr. I'rouft. U^.'. obtained .50 L'lains of rulphalo 



of nickel from 100 of this niaff*. The proccis I have io tre- 



D a (^iienily 



