I R O
I R O ( 580 )
/liape to a fallen tree has alfo been feen in thefame territory.
Native iron, in detached mafles, and of acellular texture, has alfo been found near Taborin Bohemia, and in Senegal in Africa .
All thefe fpecimens of native iron bear aftriking refemblance to each other in their beingfound in cafual detached mafles on the furfaceof the earth, in their cellular texture, and intheir chemical compofition, whence it is pro-bable that they have originated from fimilarcaufes, and the hypothefis of their having fallenfrom the atmofphere appears to be fupportedby ftrong analogy as well as vulgar tradition ;but for further particulars on this curious fub-je£t we refer the reader to the article Stonesmeteoric.
Native iron has alfo been found imbeddedin brown ironftone, fpathofe ironftone, and heavyfpar, at Kamfdorf in Saxony , and is faid tohave occurred ftalactitical with brown ironftoneand quartz, forming a vein in the mountainof Oulle near Grenoble .
It is remarkable that the native iron in de-tached mafles, or as Klaproth calls it, the mete-oric iron, is in fadb an alloy of this metal withnickel, and to this admixture it is no doubtgreatly indebted for the long refiftance that itmakes to the combined adbion of air and moif-ture. Common hammered iron is of all metallicfubftances the moft eafily corroded by ruft, yetthe native iron oxydates with great difficulty.
But although chemifts are agreed refpe&ingthe nature of the ingredients of meteoric iron,they vary remarkably in their accounts of theproportions. This difference is partly to beattributed to a real variation in the proportions,but principally to the different methods thathave been had recourfe to in eftimating theamount of the nickel.
Mr. Howard e endeavoured to afcertain thequantity of nickel by the following procefs.He firft diflolved fome pure bar iron in nitricacid, and precipitated the oxyd by cauftic am-monia, and from the refult of feveral experi-ments found that ioo parts of iron thus treated,afforded 145 °xyd; but oxyd of nickel isnot precipitable by ammonia, therefore in pro-portion to the nickel contained in the alloy willthe oxyd procured fall fhort of the eftimatedamount which pure iron would have afforded.Thus ioo grains of the Siberian iron yielded127 of oxyd of iron, hence the proportion ofnickel which it contains, is 12.5 per cent, (not17 per cent, as Mr. H. has inadvertently ftated)for
: 145 oxyd : 100 iron :: 127 oxyd: 87.5 iron.;therefore the Siberian iron confifts of
87.5 Iron
12.5 Nickel
100.0
Again in like manner the S. American ironyielded 80 grains of oxyd from 62 of the metal;hence it contained, not as Mr. H. ftates, 10per cent, but 11 per cent, of nickel, for : 145 :10® :: 80 : 55.1, hence the 62 grains confiftedof 55.1 iron, and 6.9 nickel; therefore 100part* of this contains
88.9 Iron
11.1 Nickel
ioo.®
So the Bohemian iron gave 30 grains of oxydfrom 25 of the metal, and therefore confiftedof 82.4 Iron
17.6 Nickel
100.0
Laftly the Senegal iron yielded 199 grains ofoxyd from 145 of metal, and therefore con-tained not between 5 and 6 per cent, as Mr. H.ftates, but 95.2 Iron4.8 Nickel
100.0
The South American iron has been analyfedalfo by M. Prouft, f but in a different wayfrom that followed by Mr. Howard. M.Prouft found that 100 grains of iron wire yieldedwith dilute fulphuric acid, 200 cubic inches ofhydrogen gas; but 100 grains of native irongave only 176 inches, therefore : 200 : 100::17 6 : 88, hence the amount per cent, of thetwo metals is 88 Iron12 Nickel
100
which agrees very fatisfaclorily with the pro-portions indicated by Mr. Howard.
But Klaproth , according to Jamefon, 2 hasanalyfed fome native irons with refults, if theyare corre&ly reported, widely differing fromthofe which we have juft quoted. Accordingto this able chemift the meteoric iron of Bohemiaand Siberia confifts of
e Phil. Tranf. xcii, p 191.
* Mineralog. ii. p, 2j6.