Obrázky na stránke
PDF
ePub

HIS ASPECTS.

these but different modifications, or arrangement, being thus borrowed from modes, of the same stone? His ripe as. chemistry, which, like a guardian angel, bestus, consisting of fibres which may be should always hover round and direct the separated, forms one species; while that labours of inineralogy; the other subria of which the fibres cannot be separated visions only require a characteristic clearconstitutes another. What are these but ness to assist the memory (the chief obe different modifications of the same sub- ject in any system of natural history), stance? In the last edition of Linnæus and an appropriation to the subject, so as hy Gmelin the tern, modes (modi) has to satisfy the judgment and imagination. heen applied to various appearances of From the earliest productions of Linpetrification: but what are sometimes næus to the present time, the word STRUCcalled Genera, and sometimes Species (as TUNE has been applied, with classical already observed from Dr. Townson), propriety, to denote a most striking and are, in sırict language, mere modifica. characteristic distinction between mine. tions of matter. If we pass to one of ral substances, whether on a great or on the most exact of the French mineralo, a small scale. Linnæus has observed gists, we shall find the sapphire arranged that there are only three great roads as the tenth species of the siliceous, and which can conduct the curious traveller the topaz as the eleventh; while in fact through the mineral kingdom; that of they merely differ in colour. In the mag- Physics, or Natural Philosophy, which nesian division, what are bole, fullers' treats of the obscure generation of stones; earth, &c. but different modifications of that of Natural History, which examines the same mixtures? Mr. Kirwan pre- their evident structures, and that of Che. sents no exact arrangement, but uses mistry, which considers their analyses. Classes, Families, and Branches, in such A term thus strictly appropriated, and, a manner as greatly to perplex the rea. as it were, consecrated to the science, Her : but all his species and families are has therefore been selected for the next mere modifications, and the simple divi- characteristic subdivision. sion into modes would convey a far clearer idea.

The term Mode is therfore here adopt. But as Werner and his disciples not ed instead of what are called Genera by only admit the various earths as so many some writers, and Species by others; this Genera; and their Modes, or the modi. pncertainty, of itself having demonstrated fications of the mixtures, and even cothat there are neither Genera nor Species lours, as so many species; but also what in mineralogy.

are, with great penury and uncouthness. But as it is now universally allowed by of language, styled Sub-species, with still all mineralogists, however different their smaller divisions of Varieties and Sub-vasystems, that the whole science rests rieties ; so there remains a necessity for upon chemistry alone, and that no cer. more minute discriminations in this new tainty can be found except by chemical arrangement. In his excellent and ela. analysis, the word Mode, as finally ad- borate system of chemistry Dr. Thomson mitted into the present system, must be seems to have bit upon the just and na. chiefly understood to refer to the chem• tural term, when he uses the word asCAL MODE OF COMBINATION, upon which Pect as a chief characteristic,

“ The the nature of the substances, as is now particular characters, says he, are the allowed by the greatest chemists, is yet following: 1. Aspect of the surface; 2. more dependent, than even upon the in. Aspect of the fracture; 3. Aspect of the gredients combined. It is the Mode of distinct concretions; 4. General aspect, COMBINATION wbich distinguishes a dia. &c.” As therefore the most important mond from carbon, and a sapphire from object in the study of minerals is to disargil combined with a little iron : the es- tinguish them by their external cbaricsence of a mineral consisting not only in ters, and especially by those apparent to the constituent earths, but in the pecu- the eye, the aspect becomes of such raliar way in which the mixture is modified; dical importance that it may with the and this modal influence also prevails in greatest propriety be admitted into the many artificial mixtures and compounds. distinctive nomenclature. The verb asIn short, the pretended species of former pecto signifies to view with great attention authors are merely different Moves or or earnestness, and affords a hint to the COMBINATION.

student that these subdivisions called as

pects require strict attention and discrie HIS STRUCTURES.

mination. This, the most important part of the Thus while the mode chiefly expresses

the

the difference of chemical composition, impregnating most of the others, and &c. and the Structure the grand charac. often exerting a predominating influenct. ieristic, the Aspect refers to more mi. For as, since the recent discoveries, nute features.

many earths have been known to assume

the forin of metals, so there can be no HIS VARIETIES.

impropriety in considering this universal The term curiety is unobjectionable, metal under the form of an earth. as it is equally applicable to objects of When a substance contains more than animated or inert matter; and diversity twenty-five parts in the hundred, or, in may be used to imply a siill greater dit other words, one quarter, of iron, it may ference than the cariety presents. A be worked as a metallic ore, and arvery faint shade of difference might, it ranged under that denomination. But necessary, be called a lineament.

in a smaller quantity it will fall under

the present division, especially when in TIE WERXERIAN THEORY. timately combined with the other earths. From the sketch imparted by Daubois. It was by metallogists considered as a son to Brochant, and from Mr. Jame- calx, or latterly called an oxyd. Mr. son's Geognosy, we are enabled to form Kirwan, who has rightly added calces of an idea of Mr. Werner's system concern. iron to his description of the eartlis, says, ing the formation of such parts of this that they are tormed of that metal, coin. planet, as we can hope to observe, little bined with different proportions of pure exceeding the three thousandth part of its air, and frequently of water also and semi-diameter. I warinly subscribe to

fixed air. the sentiments of admiration which are “One hundred parts metallic iron are paid to Mr. Werner's superior talents in capable of taking up 66 or 70 of pure many branches of mineralogy, a science air. When 100 parts iron contain but infinitely indebted to his industry and sa- 40 of this air, che compound is still maggacity. I also acknowledge the truth of vetic. His table of the fusibility of the the apophthegm, Natura fecit omnes ju- simple earthis presents some curious exdices; puucos artifices. But I regret, with periments on the inixture of calcined bis most enlighiened admirers, that he iron and rust of iron, with other subscene of his enquiry has been too con- stance, which show the power of this fined; and that his view of the mountains metal. Even when it only amounts to of Sasony has not been extended orer four parts in the hundred, it sensibly iathe globe. After forty years of sedulous fluences the compound. observation among the Alps, Saussure, Sidegea, or siderous earth, is so genewho began his la bours with a view of rally difused, that almost every mineral forming a system, declares that his hopes substance derives its colour from it, from were frustrated; and that he liad inet a pale blue to the deepest red. Anna with such unaccountable coniusion that substances contain it; and it exists in he could not venture to propose a theory, the vegetable kingdoin, even in plants Yet Saussure, to practical observations on apparently supported nierely by air and a far superior scene, added the advan- water. It woului appear that even we tages of learning, and mathematical and atmosphere ab unds with atoms of iron, meteorological science, which Mr. Wer whence perhaps the meteoric stones. rer unhappily wanis, and which a outil have corrected and greatly improved his

Domain II.- Siliceous. speculations.

SILEX, SILICA, OR SILICEOL'S EARTH.

This earth derives its name from the Domoin 1.-Siderous,

silex, or fiint, in which it abounds. Some SIDEGEA, SIDEROUS CARTH. also denominate it quartzose earth, be. The naine sidegea, as not unusual in cause it is perhaps more abundant in the compounder words, is abbreviated from stone calied quarız, which, whien trans. (no Gretk terms, signifying inoi) and parent and crystallized, is styled rock earth. The reasons for the introduction crystal. It so frequently occurs in the of this grand division, adopted in sub- forin of sand, which covers a great part stance by the most eminent geoogisis, of the ylobe, either alone or mixed with bave already been given. Iron acis so clay, that late chemists iufer that such importani and radical a part in the con- sand arises not only from the decompito stilu:ion of our planet, ihat it deserves sition of rocks, but is often a disturlied to be viewed under various aspects, not or hasty crystallization of silica. This only as a metal, but as an Earth, suongly is further confirmed by the circumstance known to be an original element, which to the progress, illustration, and utility of exists in the purest stare in the diamond, the science; each of them being amply and enters into the composition of side. sufficient for the ļife and labours of one rite, perhaps the most ancient of all the man; and, in this case, the subjects on. rocks. Charcoal is now regarded as a der view could not be allotted to any mixture of carbon and hydrogen. By orlier grand division. combustion it is converted into carbonic acid gas, formerly called fixed air, or ae- Domain VII.-Composite. rial acid; whence some writers have used This division comprehends the rocks the epithet aerated lime, barytes, &c. wliich consist of different substances for what are now called carbonates of blended together, and for which no disliine, barytes, and the like. The disco. tinct denoininations have been adopted. very of this new air by Dr. Black, led to Many of them have been classed under worderful jinprovements and a total re. vague names, particularly that of gra: pogation of chemistry, which in its pre. nite. sent form has been called pneumatic, Under the division of Aggregated from its spiritual fuundations. It is in. Rocks, Gmelin, in liis edition of Lilideed reinarkable, that the profoundest næus, has arranged granite, gneiss, por study, and the most patient experiments, plıyry, amygdalite, bricia, and sand, should conduct us froin matter to spirit; stone; and the reader will be surprised and thence hy a natural gradation of to find what various and discordant ob. thought, to that ineffable spirit, the Cre- jects are united under these vague ap: ator of the universe.

pellations. Mr. Kirwan has, in like The carbonic acid gas, more briefly manner, two titles of Aggregated and called carbonic acid, forms a constituent Derivative Stones ; the other rocks hepart of the atmosphere, in the propor. ing considered under the simple subtion of about 1, in the 100, while the stances. remainder consists of about 77 of nitro- The latter six great divisions of the gen and 23 of oxygen gas. Coinbined rocks, lieing derived, not from the nawith the earıhıs, it forms carbonates; and ture of the substances themselves, but that widely extended substance called froin accidences or circunstances, may limestone, which is often primeval, is a be called ACCIDENTIAL, or circumstan, carbonate of lime.

tial; while the former divisions are su BCarbon itself not only appears in the STANTIAL. The chemical Mode there. purest state in the diamond; but forms fore, so essential in the substantial ranks, ihe preponderant part, sometimes even here becomes foreign to the object ; and so in 100 of the substances now under the terms Structure and Aspect, derived view, and which have therefore been from the self-apparent nature of the called carbonaceous. They not only en- stones themselves, would become yet ter into the composition of rocks, and more improper, as by far the greater some even of the primitive, but form part of these rocks are even compounded rocks themselves, as coal has been found of various domains, united in one inass. in masses of 80 or 90 feet in thickness. The term Domain has been retained, The trivial name of sea-coal, arising from not in its former acceptation, which its inportation at London, might there. may strictly imply the preponderance or fore well be exchanged for that of rock preduininance of a particular earth or coal, as we say rock-salt. Sonie miglit, substance; but, in a more general sense, perhaps, prefer the German appellation equally applicable to all the twelve divi of bergaris, implying substances of what. sions; that is, merely a continuation of ever kind ishich enter into the composi. the metaphoric language of the Mineral iion of mountains; or the Greek grostro. Kingdom, Provinces, and Domains. In mes, proposed by Patrin, to denote the this sense it is indeed chiefly used in the strata of the earth. But as the concbi- first six divisions; the other implication, tic beds of limestone, sometimes more of predominance or preponderance, herecent" ihan coal itself, though often in ing of a secondary and subsidiary nature, thin strata, universally assume the name and only a further recommendation of of rocks, any refined discriinination its proprietý. would appear unnecessary. It has al- But ihe ierin Mode implying the che ready been more than once observed that mical inode of combination, which is the division of mineralogy into three even more essential than the nature and quite distinct and separate provinces, power of the substances combined, as METALLOGY, LITHOLOGY, and PETRALO- appears from an inhuite number of ana. cr, would be of the utinost importance lyses, it cannot be admitted into these

New

new divisions, derived from accidential, stones he distinguishes from aggregates and not fron substantial, differences, as by this, that the associated ingredients has been just mentioned ; and, the infe- are not visibly distinct, or at least rerior ternis being equally objectionable, guire microscopes to render them so. the adoption of a new appellation be. He adds, that a derivative stone may be comes indispensable. The word Nome denominated from the species (that is, tas been adopted, as short and convenie the Mode), which still predominates ; ent, and as applied by the Greek wrie but, if it participate equally of boid, it ters to the districts of Egypt, the first may receive its denomination from ei. country where chemistry and mineralogy ther. The siderous, siliceous, and argil. appear to have been studied. It is laceous earths, forin the most frequent therefore not only of classical authority, combinations ; while those of calcareous but has an affinity, so to speaki, with earth and magnesia are far more rare. the parent country of the science, and In his Geological Essays he observes, thus presents scientific recollections. The that stones are either original, as graauthor has the greatest aversion to un. nite, or derivative, as sand.stone; while, necessary neology, the chief use of lan. in liis Mineralogy, he has classed sando guage being to be understood, and that stone, along with granite, among the age the thoughts may be accurately per- gregaies. ceived, as flowers or fruits in a vase of The appellation and distinction are in cryslai; but, when a science has assumed fact alike fallacivus. That a red sanda new aspect, like chemistry, or is stone may be derived from the detritus wholly nex, like inineralogy, new words of a sed granite, may be justly admitted; become indispensable to express new

but this affords almost the only example ideas.

of a real derivative stone. And the inFor the sake of memory, and easy te. timate combinations of which Mr. Kir. ference, the latter divisions folins the wan speaks are so far from being derivageneral succession of substances in the tive, that they often belong to the most former; but this arrangeirent must not original and primitive substances. But, be understood to imply that any sub. silien Mr. Kirwan published his valuable stance is predominant, as either may system in 1794 (and the last edition is bare greater or less importance in differe merely reprinted), the knowledge of ent parts of the same sock. After these rucks was extremely confined, and reconsideraijous, the proper arrangement garded only as an appendage to mineraof the Composite Ricks will not be at logy, instead of forining a grand and tended with much difficulty.

distinct science, a rank to which its dig.

pity and importance authorise it to ay Domain VIII.-Diamictonic. pire. 'These rocks, in which the substances The tern Dinmictonic, derired from may be said to be chemically combined, the Greek, imities that two or more form the most difficult province of the substances are so the vioughly mingled, mbole science, and mighe deserve a se- or, in the language of chemistry, so ine parale creatise like the Cryptogamia of timately combined, that the rucks cane the Boianists. Siderous earth, for ex. not be arranged under either Dimaill, ample, may be found so intima:ely and either from preponderance or predomi. equally combined with the siliceous, that nance. the rock cannot with propriety le are ranged voier either. The celebrated Domain IX.--Anomalous. glazed ruck, which Saussure observed Amidst the infinite variety of nature, near the monastery of St. Bernard, is of there are many rocks whichi, though somethis description; and there is a specinen times composed of not unusual indes, are in the author's collection. It has been of so singular a structure, that they deserve called an intimate combination of qiartz to be ranked in a separate domain; mure and roche de corne.

especially as the greater part are o cis. Afost of the Derivative rocks of Kire linguished dignity and beauty. Ouriers wan belong to this Domain. The vame are entitled to this distinction from their and idea he is said to have borrowed gemmose nature, being iniaid, so from Bergman. The aggregated stones speak, with precious substances; siete as of Kirwau conprehend granite, gneiss, opaline felspar, lazulite, clorysolile, and porphery, amygdalite, sand-stune, and topaz. other substances, visibly compounded of Those fucks may also be regarded as various materials; while his derivative anomaluus which are of very rare occur

4Q2

rences

rence, and form, as it were, another class of nature, which abounds with various of anomalies from the usual laws and or. and prodigious kinds of motion and ants' der of nature. Among the latter may vrtion; and appears to be positively cons be mentioned the hills of rock-salt which tradicted by the vast force and extent of occur in Spain and Africa ; and the hills earthquakes, not to Inention inferior of iron, intermixed with quartz, to be phenomena. found in Sweden and Laplano. Tie few Ilowever this be, pyrites form an imrocks in which barytes is it.corporated, portant consideration in the knowledge inay also be annexed to this domain, with of rocks. Even native sulphur may be bituininous apd sulphuric rocks, which surid to constitute rocks at Solfaterra, are far from common.

and in Guadaloupe, and at St. Vincent's, The mineral kingdoin, as already men. not to mention other volcanic territories. tioned, is here regarded as divided into It also appears disseminated in some only three provinces, Petralogy, Litho- lime-stones, as in Swisserland and Sicily, Jogy, and Metallogy: the class of salts The fine crystals fruin Conilla, in Spain, and combustibles being divided between are intermixed with calcareous spar, on the twu former provinces. In fact, tie a rock of bluish indurated clay; and they terin rock-salt indicates the province of contribute to the elegant study of the the only salt which can properly and Gemmologist. The Metallogist has also strictly be regarded as a mineral; the frequent occasions to describe the sul. esthers being found in waters, or depo- pliurets, or combinations with sulplour, sited by them, or appearing as mere efilo. forored by many metals. If any objec. rescences, or at the most in a gemmosetion should arise to this arrangement, forin. And as the important and inter- the sales and combustibles inay be esting study of Crystallography, or Clyrys- tlırown into appendixes; for the theme is talingy, originated from the observation too confined to form a distinct province of the salls, they may be considered irs in the mineral kingdom. belonging to that department of Litho. From these considerations the rocks logy.

of common salt, with the bituminous, But the combustibles stand in a difo sulphuric, and metallic, as those of irom, serent predicament, for coal is, in many are ranked among the Anomalous; while countries, a very common and abundant those interinixed with pyrites are so trisubstance; is found in rast beds, like vial, that it is scarcely necessary to din. onany other rocks; and may, be said to tinguish them, eren from the cominon constitute entire bills, as that of St. inodes of the substantial domains. Gilles, near Liege. In this new point of view, therefore, coal bas been ranked Domain X.-lransilient. among the rocks; and that division also This division includes the rocks which includes the bituininous substanecs, suddenly pass from one to another, so which ouse from them, or may be found that specinreurs inoy sometimes even apin their recesses; while inber and melo' pear in cabinets; while the transitive bilite reniain almost alone for the minute reis commonly occur in a slow and investigations of the gemmologist. scarcely visible progress; the terın im

In passing to the sulphuric substances, plying, in Werner's system, those interit must be observed, that a most common mediate between the priinitive and seand general appearance of sulphur, in condary. The suddemess of the tranpyrites, is so interwoven with most of sition has given rise to the demonuination, The rocks, that it forints an important which implies that the substance has feature iiť petralogvo- From the Alpine leaped, as it were, from.one to another. : granites, to the lowest beds of coal, in. These rocks are extremely interesting finite are the rocks which contain pyo in the study of Geology; and the learned rites. Henkel has written a large and reader wil obserce, that this treatise learned work on pyrites; and a complete forms a gradual introduction to that sube Bovestigation mt them by the gignntic lime science, or rather study; for, evelt powers of modern chemistry, might per- in the German sense of Gengnosy, or laps decide the question so long agitated, knowledge of the shell of the earih, it wiiether the rocky shell of this planet can scarcely ever be supposed to arrive buve been consolidated, and expanded at the perfection of a science. by internal heat, or merely deposited by Great care roust be exerted not to

Tv conceive, however, that the contisund the rocks which are merely admatter of this globe is wholly inert, : herent, or composite, with thinse that scenis to be cuntrify to all the other laws really graduate into another. Saussure,

frater.

« PredošláPokračovať »