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se it, and fus are supplied in successire layers at the Arsenic volatilizes without fusing, but the commercial on the fornisce; the tire is urged by a blast (bot or supply is chiefly obtained from the oxidation of arsenical S ite toyers below. As the charge settles down ores, the arsenious oxide (As 03) being collected in a series

beoes ndaced and collects at the bottom of of chambers through which the gases are caused to pass

e beneath the fusible slag, and is drawn off as before reaching the chimney. This is sabsequently puritied. S irvit.De to time as it accumulates. Other forms Zinc and cadmium are obtained by a process of distilla

e are a so simetimes used. Both in this and the tion. The ore is mixed with a carbonaceous substance and

cases the resultant metal is impure and requires heated in a closed vessel. Jetallic zinc is reduced and n : this often involves mans and varied pro- sublimes off at a red heat. If the ore contains cadiniam

aces to the impurities present, the nature of it comes off first, and this portion is sared for special treat

the purposes for which it may be required. ment, a

i rca ile fari as kinds of cast and wrought S iirer is largely obtained from argentiferous lead ores; B e rrut varieties of steel, are produced mostly it is reduced with the metallic lead, and separated from it te crude pi, metal. Some recent improvements in by a subsequent refining process. In Patterson's process of steel demand passing notice.

for the desilverization of lead, the argentiferous lead is Accoundcf iron and carbon, the carbon being all melted in one of a series of iron pots, and then allowed to .- . Is i iron a large portion of the contained carbon cool till near the point of soliditication crystals separate :: Crior in the icon of graphite. Malieable iron is which are poor in silver, while the still liquid portion is certa; it aintains a small percentage of com- proportionalls richer in that metal: the crystals are trans2 Buth sieci and malleable iron are generails

generaily ferred to the pot to the right, while the liquid goes to that

ferred to the D P r ix iron, after a process of refining, by several to the left; in each of these the process is repeated, and die tears the introduction of Bessemer steel so on to each end of the series.

Ults in the con- s eat alteration in their production. This, centration, in the extreme leit-band pot, of a rich silver - - be dest bi as a steely-iron, is produced by alloy, while to the extreme right there is lead almost free

s u a of air thrvazh a mass of molten piz iron, from silver. in ia a se resel murable on a horizontal axis. In Parkes' process zinc is added to the melted lead.

*** CITerter; the impurities carbon, silicon, and The zinc allors with almost the whole of the silver and a

are tiias burped oil. To this blown product is little lead, and floats to the top. From this the zinc is E s Libly carboniferous compound of iron and rolatilized subsequently. By whicberer process the silver

FM .C called speigeleisen, which supplies alloy is obtained, it is cupelled, the lead and other

te aztont of carbon to the steel; the rangadese oxidizable metals being oxidized and blown off, leaving e. " zost of it passes into tbe slag, has been found finaily only pure sürer with a little gold. o f the prodact.cn of good metal by this process. Fromn silver ores the metal may be extracted by amal... - *** su.bar, and more especially pbosphorus, gamation, or by one of the numerous wet processes. In

r etbe:3tal respectively bot-sbort and cold-sbort, amalgamating the metal may be first reduced, or it may ** *n i by this process; therefore it has been be treated directly by the mercury. The latter is a waste27. ose pius prepared from rich ores free from ful process, but is that long used in Mexico, and known

Onts. By a recent modification of Thomas as the patio process, which was invented in 1557. Tłe *_ ining the converter with a basic material, ore is first ground in an arrastre, or rude kind of miil;

* cate, pbosphorus is cornpletely retnored to the pulverized stuff is added salt and magistrala te iset: the poor ores of Great Britain and else- mixture of sulpbate of iron and copper--and after some

e dered aranae, and the posploras which time mercury. The whole is then well mixed up in a

bor s subsequis rem red and utiized. suitable yard or patio, and frequently stirred; a series of T races baised a very pure una table iron direct chemical reactions set in which result in the reduction

cre with the Catalan forge, which was not very of the siver and formation of an amaican, which is * 1 CTU LATY forge-fire, the blast, however, being separated by washing.

**23 are downwards on tbe charge. A somewhat Gold is widely distributed in nature; it occurs mostly D. is stui resorted to amcay some primitire Datire, either in quartz loves or in snail quantities asso- T. dr. boomery may be considered as the ciated with other minerals. Some of the most prodactire

scarces of gold are the allarial deposits forned in tbe and seu iroan the ore cassiterite. This is reduced vicinity of auriferous rocks. From such deposits the inetal

LITT furnace with cuim and tius door spar is usually separated by washing, its stacific grarity bring ---- ASUTVC to tte gangue. Tre metal is refined so much greater than that of the stuti with which it

min., tie tin being sweated away from the less occurs. To catch tbe minute particles mercury is em... ard iron, and subsequent. r - puled," by piosed; it ama zamates readily with the natire metal. T urbo wet w ien poits, wbereby the im- Several mnetbods of wasting are adopted; the pan or dish

e e and must be conected as a scum; on is probably the sin.piest, the stat being agitated by giring -* t ot stand tbe pure tin rises to the top of the the dish a peculiar motion with the handla the cradie

the large stones are separated by a siete, and the fort ir simtalt are obtained chieir froin very com- stafi is rocked with water in an incized truagh. The - wompartint is mostiv ear piered as smalt, and from long Tom is a long ipcained trough, in which the stuff is . * ** *tle Lickel is subseco etir extracted subjected to a gently running stream of water. Tbe most - 2 artimusay are most separated by lique- adrastagions method of treating the stuff, where it can

- 120 t ab olars native with a quartz guzue, be adopted, is the bydraulic method used in C uria; 2.

in an incided vessel tbe metal fases and bere a powerful jet of water is projected fron a large

It is saveggentis parited. Altinony is Dostly bose against the bank of garel; this breaks it down, and e

from the pude st buite (SDS), which is an the water with the suspended particles, as it rucs cff, is - N e peral, and can be separated from the treated in long trongis (sumes) often miles in len th, in 8 -> 2011. This is tbed roasted and tbe metal the bottom of which mercury is placed under farcarE

by charcosi add soda-ash; or the liquated able circunstances stuff containing not more than one - -. - bizse w.th iron, yieiding solide of irun mismooth part will pay for working by this metbod; but List DDT.

the preaninary expenses, bringing tbe water under suitabie

METAMORPHISM.

223

METAPHYSICS.

sedimentary origin. The precise cause of the alteration is 1 to be found in almost all mountain chains and areas of a matter of some uncertainty, but that pressure and heat disturbance, as well as in districts that in some former with or without the presence of water--are potent geological period represented the axis of a mountain range,

rences, there is little reason to doubt. At least three since removed by denudation. fonetisct kinds of metamorphism can be recognized, due The third type of metamorphic action is that produced prently to somewhat different causes.

by chemical action, to which the term methylosis has been Local metamorphism, or that found in the vicinity of applied. It may be due to the reaction of certain constrive and eruptive rocks, is of comparatively limited stituents of rock upon each other, or it may be due to the out: it consists of a baking and hardening along the effect of meteoric waters or other solutions on particular

fights of the intruded rock. The zone so affected varies beds of rock. Thus many granites undergo a sort of 31. the size of the igneous rock. Frequently between lava decomposition or disintegration, which converts them into

us the rocks are found to be indurated and porcellanized growan or sometimes kavlin, even to considerable depths. Ar tās intiuence, but whereas the rocks on both sides of The same is true of some elvans and certain other igneous

atrasire mass are affected, in the case of eruptive rocks found in dykes and sheets. A remarkable instance - es it is only the beds immediately beneath the lava of methylotic action is to be found in the formation of * * that suffer this change. The various kinds of rock certain serpentines, as those of the Lizard, Cornwall, which * c coarse altered differently both in degree and in re are altered diallage-rock, a variety of igneous rock. Many

Dt product. Shales and clay rocks are converted into of the serpentines of the Laurentian formation of Canada me and generally compact flint-like rocks; those contain appear to have had a similar origin. The induration and

- frites and protoxides of iron hare usually a burnt silicification found affecting the country rock along the conTridened aspect. Sandstone and quartzose rocks are fines of a lode or other mineral deposit, and often penetratrasy affected according to their accessory constituents, l ing certain beds formerly porous, belong to this class of

Enestones are rendered more crystalline or converted phenomena, and has probably been effected by a hot solution saccharoid marbles; to this latter change the term bearing silica in solution, that flowed through the fissure

trvais is sometimes applied. Numerous examples of where the lode has formed. Laal metamorphism or paroptesis, as it is sometimes There is almost an infinite variety of metamorphic rocks; ei, are to be found both among ancient and more the most commonly occurring are, however, the various micrmations. At Portrusb, in the north-east of Ireland, schists, as mica-schist, hornblende-schist, &c., named * L sbales are converted into a hard flint-like rock, after one of its chief constituents, and the several gneisses

mly resembling a compact fine-grained basalt, but in passing into metamorphic granite. It is being gradually * * Iossils, especially Exogyra, are still well preserved. | conceded by geologists that a number of the rocks formerly

sith the basaltic flows of Antrim the chalk is converted considered as of igneous or plutonic origin are more di a compact and hard stone-the white limestone, probably due to metamorphic action, and many consider it ng with a flint-like or conchoidal fracture.

as possible that volcanic rocks are but an extreme stage of Primal metamorphism affects areas on a larger scale. the same action, which has resulted in the complete fusion

districts are often found composed of these rocks in and ejection of the rock. teba bedding is still quite apparent and usually quite METAMORPHOSES OF ANIMALS. See LARVA.

; bat whereas one bed may be a highly crystalline METAPHYS'ICS. Metaphysics is a word which has *Letter gneiss or apparently a true granite in com- | received definitions various and apparently contradictory, I , the adjoining beds may be comparatively unaltered but the most important of which are, nevertheless, ultimately

m r mica schists, or even crystalline limestones of a reconcilable. The best agree in representing it as the 224-Tay colour. When examined on a large scale these science of the primary principles of human knowledge, or * 2 are found generally to be plicated and folded; and it that which determines the ultimate meaning, foundation, and

ty'erarked that the more the strata are folded the limits of our beliefs. And as the solution of its principal matersily are they altered. Foliation is associated problems implies a systematic study of mind, it has also

erwth metamorphism; the minerals appear to develop been described as the science of the facts or phenomena of - aal planes, soinetimes coincident with the stratifica- consciousness—the fundamental facts in the universe. As ** at other times with the cleavage, when such existed. expressive of summary or ultimate science, or at least of

lat case of local metamorphism it is evident the change the aspiration after it-the aspiration after the purification - nina y sedimentary rock has been brought about by and perfection of our intellectual life-metaphysics and Tinity to an intensely heated mass of molten rock; in the philosophy are used often as synonyms.

*Ares mul metamorphism it is different. Here the strata The origin of the term metaphysics is obscure. It was - tfub a thickness and altered over such vast arcas probably first applied to those books of Aristotle which

ther cause must be sought. The explanation most profess to unfold a Science of Being, and which, in the * accepted is that of aqueo-igneous fusion, which is arrangement of his works, followed his Physics. They od by the experiments of Daubrée. According to were accordingly called by his editors "those after the un, since their deposition these strata have been Physics" (Gr. ta meta ta phusika); but whether on account

i c der a considerable thickness of superincumbent of their position or because it was thought they should : **. When in this position, and under considerable follow the Physics in the educational course is uncertain. *» , try were subjected to an elevation of temperature, This, then, is the accurate meaning of metaphysics- the evat upon their being further from the surface of the body of inquiries on the subjective method into the nature , aud possibly aided by the heat produced by the of things lying outside human experience and the possibilaz of the rocks. At a comparatively moderate ities of experience, such subjects as God, freedom, immor

ure it has been found that rock-material, con- tality, cause, existence, &c. Ontology is another name, W snall percentage of interstitial water, undergoes and philosophy in its restricted sense yet another. Of the

sal change, wbereby new minerals allied to the con- futility of this kind of inquiry most men are now convinced. 13 of geiss and granite are formed. It is therefore Many believe they have divine revelation as to the higher

that the majority of these metamorphic rocks order of things, and in this they trust with awe and rever* en formed by an incipient fusion, under great present faith ; but to speak of knowing such things is to use - Od in the presence of water. To metamorphism of the language of bygone times. From Aristotle down to

kad the term metapepsis has been applied. It is by | the beginning of our own century the problem has been De tost abundant type of metamorphic action, and is attacked, and no progress has been or ever can be made.

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