the place of classes; and with what immense superiority of precision and science, must be manifest to the most obtuse intellect; only it might have been as well to mention, what are the exact dimensions of great and small.

The provinces are again to be subdivided into DOMAINS, and Petralogy has twelve allotted as its share.

The first six being distinguished by the substances themselves, may be called SUBSTANTIAL; while the remaining six, being distinguished by circumstances or accidences of various kinds may be called CIRCUMSTANTIAL OF ACCIDENTAL; but this last division is of little moment.

The first six domains of petralogy comprise, 1. The siderous rocks, or those in which iron predominates, not in the comparative quantity when analysed, but in the quality and essential difference which it imparts. 2. The sileceous, denominated as usual from the quantity of silex. 3. The argillaceous. 4. The magnesian; these two are again denominated from predominance. 5. The calcareous. 6. The carbonaceous.

The remaining six domains, derived from circumstances or accidences, are seven, the composite, or aggregated rocks, as calcareous spar, with schorl, quartz, and garnets, felspar, and siderite, or hornblende, &c. This domain has often been confounded with the granites, however alien from that description. 8. The diamictonic, or rocks in which the substances are so completely mingled, that it is difficult, even upon an analysis, to pronounce which predominates. 9. The anomalous, or those which contradict the common order of nature, and present unexpected and unusual combinations.

Some of these domains, though they afford few objects at present, may in the progress of science, be greatly enriched and enlarged; and the utility of such divisions will be more perceptible as the study advances towards perfection, the greatest obscurity at present arising from want of necessary subdivisions.

The remaining three domains are generally admitted in geological works, namely. 10. The transilient rocks, an interesting series, in which one substance gradually passes into another, as granite into porphyry, trap into wacken, and the like. 11. The decomposed rocks, which gra dually decay into sand, clay, or productive soil. 12. The volcanic, which require no other description.' pp. iv, v.

These domains, must serve as a substitute for orders.' The smaller distinctions,' Mr. P. informs us, 'can only be derived from the objects themselves,' and what are denominated species, in the arbitrary and unnatural systems' of mineralogists, are henceforward to be called modes, which must be chiefly understood to refer to the chemical mode of combination upon which the nature of the substances, as is now allowed by the greatest chemists, is yet more dependant, than even upon the ingredients combined.'-A definition of combination,' and the nature of substances,' would not have been misapplied in this place.

This, the most important point of the arrangement being thus bor rowed from chemistry, which, like a guardian angel, should always hover round and direct the labours of mineralogy: the other subdivisions only require a characteristic clearness to assist the memory (the chief object in any system of natural history), and an appropriation to the subject so as to satisfy the judgment and imagination. From the earliest productions of Linnaeus to the present time, the word STRUCTURE has been applied, with classical propriety, to denote a most striking and characteristic distinction between mineral substances, whether on a great or on a small scale.' p. viii.

6

Leaving this singular definition of the word structure to the consideration of our readers, we have only to remark, that, instead of the sub-species, varieties, and sub-varieties,' as they have been called, with great penury and uncouthness of language;' Mr. P. out of the riches of his classical stores produces the terms aspect, variety, diversity, and lineament!

Having advanced thus far, the next step is, to shew the incalculable value of his own system, which he attempts by instancing the embarrassments of his predecessors. Whether he can gain disciples simple enough to believe, that the difficulty of distinguishing between different kinds of minerals, is removed by calling them modes and aspects, instead of species and varieties, we know not; but this is really and truly the sole amount of his pretension, notwithstanding it is cloaked beneath four pages of extract from Werner, (whom he is equally ready to use and abuse ;) half a page from Ainsworth, to instruct us in the ancient and classical senses' of the word species; and a page from Saussure: notwithstanding, too, this division of his work is enlivened with a sneer at the truly risible pedantry of Milton,' whose logic was the art of talking nonsense according to a fixed method; a blow at the prolix, confused and digressive style of Dolomieu' and his strange, very curious, and original specimen of a definition!' and a thrust at Werner's truly German distinctions and lastly, notwithstanding the curious information, that the word species chiefly belongs, with the greater part of the Linnean language, to a modern latinity so barbarous, as even to confound gender and cases and many others of the commonest rules of grammar.'

'

The second section treats of the order of the distinctive characters. These he has arranged in the following succession: texture, hardness, fracture, fragments, weight, lustre, transparency; to which,' says he, colour is sometimes added though the most vague and insignificant of all the characteristics. This last observation is only very partially true, as there are minerals in which colour is of the greatest consequence and perfectly distinctive, as in several of the lead and

iron ores, though certainly it cannot be made indiscriminately of equal importance in every case.

The different comparative degrees of these characteristics, have been generally denoted by the ratio of numbers, the extremes of which indicated the maximum and minimum in which such a property could exist. It is difficult, no doubt, in such an arbitrary scale, to attach precise ideas to the numbers; but the difficulty arises from our want of means to compare the intensity of the characteristics themselves. Mr. Pinkerton, therefore, only renders bad worse, by introducing a set of terms to express this ratio, whose relation to one another is equally indistinct. His terms for weight, are pumicose, carbonose, siderose, and barytose; for hardness cretic, gypsic, marmoric, basaltic, felsparic, crystalic, corundic. Now, it is scarcely possible even for Mr. Pinkerton to suppose himself a jot the wiser when these terms are applied to the substances from which they are borrowed, as when coal is said to be of a carbonose weight, and felspar of a felsparic hardness. And when they are applied to other substances, unless you remember the order in which he has arranged them, that is, unless you reduce them to numbers in the mind, you have still no scale of comparison with minerals in general. You simply learn that this or the other substance is as hard as corundum, or as heavy as barytes, without knowing whether corundum is one of the harder or softer minerals, or whether barytes is heavier or lighter than pumice. How greatly our language has been enriched by these ingenious adjectives we do not pretend to determine, but must inform our readers on the part of the author, that

While some recent authors of mineralogy pollute the classical language of our fathers, with an inundation of barbarous German words, derived fron the vulgar dialects of illiterate miners, who, of course, first observed the distinction between mineral bodies; it became the more an object of ambition to treat this difficult subject with such a degree of classical purity, as not to disgust the eye of taste, contemn the discussions of grammar, or vitiate the eternal tenor of our language.' p. xx.

The quotations in this section are: Dr. Townson on Texture, and Werner on Hardness, which are given with due exactness, even to Werner's note, informing us that knives, files, magnifiers, &c. are to be met with, well made and adapted, at Mr. Schubert's, Mechanic to the Academy of Mines, Fryberg.' And lest the beginner might suspect that the hardness of minerals is to be tried by his teeth, he is distinctly reminded four times, that the proper instrument for this purpose is the knife.

The third section is entitled 'Remarks on Werner's Geognosy, or System of Rocks.' These begin with the assurance, that we can hope to observe little exceeding the three thousandth part of the semidiameter of the earth." Now Chimboraço is 20,000 feet above the level of the sea, and were the strata placed in the most unfavourable situation, that is, horizontally, we might still reasonably hope to become accurately' acquainted with so much of the earth's diameter. Nay, even the strata of our own country present a succession amounting probably to above three miles, which, arithmetically expressed, will convince Mr. Pinkerton that there can be no difficulty in observing a portion at least three times as large as he supposes. We are, however, very much inclined to suspect, that Mr. Pinkerton's ideas of stratification are far from being substantial and tangible.' He complains that there are not sufficient proofs that granite is the universally radical rock,' because if we examine the accounts of the substances found at the greatest depths in coal mines and other excavations, there is no appearance of granite!' p. xxx. He seems to think that plains, as being nearer the centre of the earth, have lower strata than the mountains. p. xliii: and seriously hints that coal may be expected in Surry, if it be true that iron is generally an indication of that substance. p. 96. He is also so anxious to disprove the necessity of studying rocks in nature, that we are involuntarily reminded of the animal, who found the fashion of no tails so peculiarly convenient and becoming*. It is therefore by no means a matter of astonishment, that he dissents from Werner, (and indeed every other author in existence,) and refuses to adapt his work to his system, for

'If a work of petralogy were founded upon this theory, it must fall with it; and no writer of judgement or industry, would choose to risk his labour upon such an uncertain foundation.' p. xxxi.

* Mr. Pinkerton's arguments upon this subject are of such a very homely kind, that we cannot avoid giving them in his own words, for the consolation of such of our readers as may happen to be in the same predica

ment :

• Petralogy, therefore, or the knowledge of rocks, must, like the other branches of mineralogy, be studied in cabinets as well as in nature; and in the substances themselves, not in supposed theoretical positions; for if the student cannot distinguish a rock without these adventititious aids, (nature and theoretical positions), which in the great variety of nature, will themselves often lead to false conclusions, he may be pronounced as truly ignorant of the subject, as he who cannot distinguish gems without being informed of their countries, sites, and gangarts. And this would be the more absurd, as it is self evident, as already observed, that large substances must present more palpable and more numerous characteristics, than the minute,' p. xxxiii.

In section the fourth, our author pleads for the admission of iron,not as a metal, but as an earth. His meaning, as far as we are able to discover it, is, that since iron imparts characteristic properties to several minerals, it ought to afford a title under which they might be arranged; but we confess that we are unable to divine why it is not to be admitted as a metal, which it must and will remain whether in the form of carbonate, oxyde, or any other chemical combination. Mr. Pinkerton adduces Sir H. Davy's recent discoveries in his defence, since they

evince that the alkaline earths, that is the calcareous, magnesian, barytic, strontianic, are of a metallic nature or yield peculiar metals, while he suspects the other earths to be in the like predicament (as the siliceous has since proved), it would be absurd to reject iron as an earth, merely because it yields a metal. p. xli.

But the fact is, that though Sir Humphry's experiments have brought the earths under the appellation of metals, we are by no means at liberty to call the metals earths, or to make the two terms synonymous, unless we intend to render one or the other superfluous. The earths still remain united by so many common properties, and separated from the other metals by so many distinctions, that we must preserve them as a particular class, either by giving them a new name, or, which is evidently more rational, by new modelling the definition of their old appellation. Perhaps their retaining a stronger attraction for oxygen than that of carbon, even in the highest degree of heat which we are capable of producing, would be sufficient. At any rate, we protest against reestablishing the old reign of the metallic calces under the name of earths, and the needless multiplication of appellations by calling oxyde of iron, sidegea and siderous earth.

The introduction is closed with a fifth section, which con. tains miscellaneous observations. The first ascribes the slow progress of mineralogy to its being too wide for the labours of one man; and extols the utility of general systems or compilations,' concluding with the remark that, In this also, as in the other sciences, more genius is required to build a system, than to make observations. In the latter, Newton must yield to Herschel.' p. xliii. The inference intended, we leave to our readers, lest we should offend Mr. Pinkerton's modesty.

The second observation is on petralogy and geology, and only proves that he knows nothing about either. The third exposes the futility of small tours. When an author in his cabinet, studies the whole globe, and the collective labours of two thousand years, these little journeys only impress him as puerile excursions; and, in conversation, he regrets to find