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Show 3· " HENCE dulky I~oN Deeps 1n dark abodes, And ferny foliage nefiles in the nodes ; Till with wide lungs the panting bellows blow, And waked by fire the glittering torrents flow; Hence dufly Iron. 1. 183. The production of iron from the decompofition of vegetable bodies is perpetually prefented to our view; the waters oozing from all mora!Tes are chalybeate, and depolit their ochre on being expofed to the air, the iron acquiring a calciform fl:ate from its union with oxygene or vital air. When thin moraffes lie on beds of gravel the latter are generally ftaincd by the filtration of fome of the chalybeate water through them. This formation of iron from vegetable recrements is further evinced by the fern leaves and other parts of vegetables, fo frequently found in the centre of the knobs or nodules of fome iron ores. In fome of thefe nodules there is a nucleus of whiter iron-earth furrounded by many concentric fl:rata of darker and lighter iron-earth alternately. In one, which now lies before me, the nucleus is a prifm of a triangular form with blunted angles, ;mel about half an inch high, and an inch and ha.lf broad; on every fide of this ar.e concentric fl:rata of fimilar iron-e:uth alternately browner and lefs brown; each firatum is about a tenth of an inch in thicknefs and there are ten of them in number. To what known c:mfe can this exactly regular di(hibution of fo many earthy flrata of different colours furrounding the nucleus be :1fcribed? I don't know that any mineralogifls have attempted an explanation of this wonderfu l phenomenon. I fufpect it is owing to the pol.uity of the central nucleus. If iron-filings be regularly laid on paper by means of a f1nall fievc, and :1 magnet be placed underneath, the filings will difpofe themfelves in concentric curves with vacant intervals between them. Now if thefe iron-filings are conceived to be fufpended in a fluid, whofe fpecific gravity is fimilar t~ their own, and a magnetic bar was introduced as an axis into this flnid, it is eafy to forefee that the iron filings would ·difpofe themfelves into concentric fpheres, with intervals of the circumnatant Huid between them, exaCl:ly as is fccn in thefe nodules of iron-earth. As all the lavas confifl of one fourth of iron, (Kirwan's Mineral.) and almofl: all other known bodies, . whether of animal or vcgetJble origin, poffefs more or lefs of this property, may not the difhibution of a great portion of the globe of the earth into fl:rata E)[ greater or Jefs , "1:egularity be owing to the polm ity of the whole? [ 77 ] -Quick whirls the wheel, the pond.erous hamm~r falls, Loud anvils ring amid the tretnbling walls, Strokes follow flrokes, the fparkling ingot :!hines,. Flows the red flag, the lengthening bar refines; Cold waves, immerfed, the glowing mafs congeal, And turn to adamant the hiffing SteeL " Lafi MrcHELL,. s hands with touch of potent cli.ann· The polifh' d rods with powers magnetic arm; Jlnd turn to adamant.!. 192. The circumfl:ances which render iron more valuable to mankind than any other metal, are, 1. its property of being rendered hard to fo great a degree, and thus confiituting fuch excellent tools. It was the difcovery of this property of iron, l'v1r. Locke thinks, that gave fuch pre-eminence to the European world over the American one. 2. Its power of being welded; that is, when two pieces are made very hot and applied together by hammering, the.y unite complcatly, lmlefs any fcale of iron intervenes; and to prevent this it is ufual for fmiths to dip the very hot bar in fand, a little of which fufes into fluid glafs with the fcale and is fqueczed out from between the uniting parts by the force of hammering. 3· Its power of acquiring m:~gnetifm. It is however to be wifhed thJt gold or filver were Llifcovered in as great quantity :as iron, fince thcfe metals being indc:firuCl:ible by expofure to air, water, fire, or any common acids, would fupply wholefome veffels for cookery; fo much to be defired, and fo difficult to obtain, and would form the mofllight and durable coverings for houfes, as well as indcfhuClible fire-grates, ovens, and boiling ycfli:ls. See additional notes, No. XVIII. on Steel. · Lafl Michell's hands. l. 193· The difcovery of the magnet feems to have been in very .early timc.s; it is mentioned by Plato, Lucretius, Plin y, and Galen, and is faid to have taken its name of magnes from Magnefia, a fea-port of ancient Lybia. As every piece of iron which w::s made magnetical by the touch of a magnet became itfelf a magnet, many attempts were made to improve thefe artificial magnets, but with, out much fuccefs till Scrvingdon Savar~, Efq. m~d c them of hardwcd flee! bars, \\ hidt |