METEORITIES.

Thames Star, Volume VII, Issue 2568, 31 March 1877, Page 6

METEORITIES.

By Professor A. C. Young

(?BOM THE BOBTOK JOURNAL OF CHEMISTRY.) In the present article we propose to consider the so-called detonating meteors, or bolides, which from time to time fall upon the earth as mnsses or' stone or metal. It may, indeed, be-a- question' whether the«e bodies n-al!y differ from the ordinary melfO's in anything but size; mnny of tlie lii|.'lte*>t ttuthnrilit'S think they do n -t. M li,,tlie iact that e^eji during the mo>t metroric s-lmwers uo sound has ' een £e t nl and not a single IrHgrrieni. has been know ii to reach tlu> jjiound, seems to warrant us in cla-ssin^ the bodies by themselves, at least provisionally. They appear to bear much the same re'ation to tfire shooting stars which planets do towards comets. As late as 1800, men of science in general were disposed to be very s"pptical as to accounts of stones and iron fallinu fiom the shy, and tboe who udmittpfl the fact had n-rourse to nio*>t curious ami a!)Mird hypotheses to account for it; some, for instance, thought lhe stnnes w^ro formed in the air by lightning, while otht rs maintained that they came fro'Ti volcanoes on the earth or moon. Chladni, however, in 1794 published a paper upon the origin oi a remarkable mass of native iron found bj' Pallas, the explorer, in Liberia, maintaining it-to be meteoric, as is now universally admitted ; and to strengthen his position, he went into a careful '-criticism of various accounts of the Call of such bodies, compiling a• ; catalogue of some 300, and . ; affirming 1 heir credibility." His reasoning made an ■impression,! but still failed, to eiit'orco genera^ assent, uhtii^in 1803 lan event occurred which, put an end ti airscepu'cism. 'Oii the 26<h of April" iii.'t.hat'■■y.e'n'r a meteor exploded over.the Tillage! of L'Aiglej in . Normandy; within 85 miles ot. Peris, and more than. 2.000 fragments, of weights ranging from ,201b. tuia fraciomof an ounce,-were scattered o»'ec: a-'-r'e'yi«»n of several 1: miles. - The • Afa'Hrtn'y of Sciences' senta special committee to investigate the matter.;' They collected specimens, took the sworn depositions of those who had' witnessed the phenomena,, and in "their report put the jv*»lifv-of t Ite occurrencip ;bey<phd all,pos-. sibledoubt.- ;;. ":;';" •/ :K'\- ' : '"!„''. '■'.. \[ '■' '.';'■' Tlie phenomena which; accotnpany the fill of thes.e bodies are much the same as tlibs.e of the shooting stars, except :trW;; t!>py. are, ordinarily,, far; more brilliant; aid observers who are. near the path, of tie. meteor usually hear a rnahinii roar. 1. ii»' : that of a heavy railroad train;, accen-; t mted. by srveral: cannon-like reports.----w'ni-l". are sometimes heard at a distance: of 100 miles. Ateach of these.ex< losions, whose c»use is only doubtfully explainer, flip m«tror changes its rourse or brr»ks into fragments. In a Jew instances, when t e-fait tuot place, in the daytime; no 11minous -\>\\ enom en/t...vrere seen, an<l in one or two cases the '■fall of veiysmal! a •'•olites lia< been unaccompanied by naise. Thus-in March. 1856 there was a B •pvrer of l.ttle stones in Harrison country, iriviiaiia. one crt which was ahouf as large a* a marble, fell within a few feet of a man and his wife who were: standing in t-ieir cabin, with tio other warning 1 than t>«», teiiririg of 'the. missile thjfou2h£th«: leaves of the trees. The character of the S::one; ard of several others which jfolljat; tie same /ira'e.; reuioyes all, doubt as totiieirmeteorict orgin,, .... : -.!' >. 'A'\ ':.■■'-. There are several instance? ,on recqrd of niiseliie! done, hyraeteorsi; In 1511i:a monk; wa< killed by one at Crema; in -1650," an^ oth<?r monk at Milan ;>and.: in -1764, Jtwo s tilers on a ship in...the Baltic. One of . the aerolites which fell at Barbotari in 1790 broke through the roof of a^ house, andlVkilJeUi» peasant aniTa bu}lpe]e.| j j U w When these bodies have fallen among the ignorant andisnperstitious.-.they have usually been .regarded., with great reverence, and becojne objects of worship. The Palladium of ancient Troy, which; by some writers is described as a shapelpss mass, is supposed,to Jiave been an.aerolite • so. alsf, the; image of I)iana .of !Eplresus > that fell down from! Jupiter, and ;the mys-j •"■ terious black stone'orthe Kaaba at Mecca." The stone which fell, at" Parnallee in Southern India, in, 1857, was for some time worshipped by the natives. The number of meteoric falls is very considerable, our cabinets now. containing specimens derived from nearly 300 different localities; and if we ndded^the specimens which .are- supposed -to; be of meteoric or gihi'tiiougb! the dfite b'f rtheir fall is unknown, we must at ijeast-double the number Kecalling-nowihpw-small a' portiort of all that reach itheeacth would. i ever be_found, because so^ much of her ! surface is covered wUh water,' or forest, 1 or desert, it becomes evident that the j total number of sueh;e'v'ents"is to be counted by the thousand in every century. I In fact, -.th&i scientific journals usually ' contain>the; notices of some five or six-i on the average, every.year. Meteorites differ greatly,in size.-'. They ' seldom fall singly ; but the mass which j enters the atrnosphere,'chilled to the iem-1 perature of interplanetary space, breaks up, under the action of the sudden and intense heat-generated: by the resistance of the air! intofrauments which, asi a rule, Beldem exceed: 1501b. in weight, while the ' majority are much smaller, say from2o!b. to a few ounces. Since, lio« ever the number of fragments is so often^-v.ery^-'gre.a.t, the total weight of'a sinyle meteoric mass^ sometimes amounts.to tons- -This seems to have been the case with the shower of stones that fell at VVeston. Conn., in IPO7, and the more recent fall at New Concord, Ohio, in 1,860. ■ lhe diffi-iv'nt specimens from the samei fall of course always closely n semble each other, b^ing merely fragments'of a single mass, but aerolites from different falls diflVr widely in almost every respect, with, however, a few marked features of resemblance. They are always coated with a thin, black, highly magnetic crust, formed by superficial fusion, and: they invariably contain a considerable amount of iron, ranging from 20 or 25 per cent, to 90. They may, according to Maskelyne, be broadly classified into three divisions —The iron meteorites, or siderites ; the stony meteorites, or aerolites (airstonos); and an internuediate class, represented by exceedingly rare specimen 8, which consist of a honeycombed mass of iron filled in with stony matter, and known as siderolites (steel stones).

SIDEIiITES. ' Compared with the aerolites, the siderites are very rare. As yet only five cases are on record in which meteoric iron has been seen to fall—At Agram, in Bohemia, 1751; Dicksoa county, North Carolina, 1835 ; Braunau. Austria, 1847 ; Victoria, South-Africa,. 1862; - and Mays-

vil'o, California, 1873. A recent fall iu^ TsfevarTa is reported to have consisted of meteoric iron, but the report needs confirmation. While, however, the instances are so few in which the actual fall of iron masses has been observed, we have in our cabinets some 200 specimens of native iron, winch, from the circumstances under which they were found, and their resemblance to the Agram meteorite in chemical constitution and crystal structuro are pretty; "certainly concluded* to bo of meteoric, origin, t Such r< are the meat masses from Orange River in the Br tiah Musj ura, the lied Kiver iron from IVxas in llie - cabinetof r -Yrtle.£!oUege, and the Ainsa'iron' in the Kmit'hxoiJiau rooms at Washington. A marked peculiarity of all-meteoric-iron is its alloy with a considerable quantit/ ©f nickel, varying from sto 15 per cent. A'second characteristic consists in a peculiar crystalline structure, which, is * best brought-out by polishing a cut surface and cacting upon-it *ith a',weak" acid.' Quite. recently, also, Graham and others have found that a laige quantity of hydrogen, and smaller amounts of carbon oxide and other gases, chiefly hydrocarbons, are included in the pores of meteoric iron, and can be liberated by heat.

''. :::■;■■ aebot.itks. ' /"" "'"". The aerolites, or stony meteorites, which form the vast majority of 1 all that have beeri seen to fall, differ very'widely'' among themselves. Some are hard and compact, while others are as friable as rotten stone. ; s 'l h.e t aerolito of Bislippsvil'e.' &.C., though 'covered with, the invarible : black crust, is, internally, almost as white as chalk, and es light as pumice ; that*pf ;Kold BokkerelrlV* South Africa:.-on the' other hand,'resembles a piece of anthracite coal more than anything else; and that of Orgueil, aimasji of rather'coht'rent" garden soil. . Tbevmajomy,-however, are heavy, greyish roclrlj sonfething like sandstone, made up""of crystals or minute spheres of variou>i pt'culiar minerals (many ,of .yvhich aro never found in terrestrial j rbcts),' interspersed with nodules of mcfceliferous iron, and c mented .together by compounds of the oxides of iron.- If exposed to atmosphe/^Vinfluence for a few years only,-tlie rh;a"ss di>iritegi*«tcs and falls to pieces ; and this probably explains why so few aerolites have ever been found, ; except in immediate c nnection withtheir fall Thesiderireo.', on the other hand, ■ remain for centuries but slightly altered.

; ;Accord.ing >to Maskeilyjjei the following .24 elements have been detected in aerolites, namely, hydrogen, lithium, .sodium, potassium, magnesium, calcium, alumi.nium, titatium, chromium, manganese, iron, nickel, cobalt, copper, sulphur, tiu, ;antimony, arsenic, vanadium, phosphoirous, oxygen, silicon, carbon and chlorine. i The first 15 of these are also shown by ithe r-pectroscope to exist in tbe sun, tojgether with zinc, strontium, and cadmium, which,, thus far, have not been found in meteorites. :- _•■" ■ ORIGIN OF METEORITES. . Tlie origin of these bodies is, as yet, a matter of speculation. They enter our :atmosphere; -how^yer, with a telbcity so -great (often exceeding 20 miles per second) as to make it certain that they do not I'ome from any terrestrial source, or even from the moon. And for the same reason itliey cannot well be, as some have thought, ".the minute outriders of the great family asteroids," for then the velocity with ; which they would rVacTi us would be only ;the.difference between,theirrelucity and ;ours. It seems .impossible to: avoid |the conclusion that their orbits must be .unplanetary, not approximately circ^ulari'but'v'ery'eccentrici like those ot comets and the ordinary shooting stars. It may. be, as Mr Proctor has-suggested, that 1 some of them, the siderites „especially, have ejected from our own or some other Mm l>y some of tbose tremendous out- ; ibursts of .solar enegy whu-h we occasionally observe w!ith. our spectroscopes ;: or they may have originated, as fi^oignp'argues, in the cracking to pieces of soWe .old and used-up world.

; At present,, all we ltnow is that-.they^ come to us from the-puter darki.ess of in- r terstellar space. As Humboldt lias said— :" They ; prtvsent to us the s.Qlitary iqsijance: of a material connection with somotb.ing which is foreign toour planet. " We are astonished at being able to touch, weigh and chemically decompose, metallic and Jearthy; masses which: belong to^the oiiter world—the celestiai space, and-to find in them the elements of bur native earth, 'making it probable, as the great I^ewton conjectured, that the materials which; belong to our group of cosmical bodies are, for the most part the same/'-; ft- };.;>