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No cunning can pervert, no dullness can obscure, the visible connexion of cause and effect in the above instances. Spain, possessing the most fertile territory in Europe, troops the most renowned for discipline and bravery, a triumphant fleet, and the wealth of both Indies flowing into the coffers of the most religious and legitimate monarchy:-all these combining to form a paternal government, thrown off by a horde of fishermen! The fishermen becoming, by the very struggle, scientific captains, valiant soldiers, daring seamen, rich merchants, sober and industrious mechanics :-erecting a splendid state, and maintaining, against the greatest legitimacy of Europe, an illustrious independence, with a revenue which hardly exceeded three millions per annum, and a territory amounting to about one-third of Ireland.'-pp. 108, 109.
We need not pursue the comparison with Prussia, and with the United States. The object which we have in view does not require of us to go into the history of the revolutions which have been successfully effected in the New World. We are much deceived if the extracts which we have already taken from the able and interesting work before us, are not sufficient to shew that, in case of a foreign invasion, Ireland, if by any chance she should be left to her own resources, would be fully competent to maintain her independence. When the apprehensions of her protecting power shall be dissipated on this subject, it will not be difficult to convince the people of England, that it would be highly advantageous even to them, not to speak of the people of Ireland, that the latter should have a domestic Parliament and administration, without producing any change in the allegiance which they owe to the house of Hanover.
We have now laid before the reader the substance of the first part of this curious work. We have done so at some length, as we believe that very few copies of it have as yet found their way into this country. We understand that the second part, which is already in progress of preparation, will disclose much of the proposed military systems of General Tone and Lord Edward Fitzgerald, which have hitherto been very little understood. They likewise contain a criticism upon the present military system of Europe,' with a view to shew that it is founded on an erroneous basis, that of separating too widely the soldier from the citizen.
ART. V.-Elements of Chemistry, including the Recent Discoveries and Doctrines of the Sciences. By Edward Turner, M.D., F.R.S.E. Professor of Chemistry in the University of London; Fellow of the Royal College of Physicians of Edinburgh, &c. &c. Second edition, enlarged and carefully revised. 8vo. pp. 822. With plates. London: John Taylor. 1828.
THIS is, in many respects, an admirable work, on one of the most. extensively useful branches of physical science-a branch, without the knowledge of which it is impossible to understand well or thoroughly almost any investigation of the productions or pheno
mena of Nature, or almost any of the countless processes of human art and industry, so widely are the connections of chemistry ramified among the subjects of study and of skill. Accordingly, the astronomer and the optician must depend upon chemistry for the perfection of their instruments, and the character of the media through which light is transmitted; the meteorologist for the nature of vapours and the chemico-electric affections of the atmo sphere; the pneumatician for the combinations, mixtures, and specific gravities of the various gases; the hydrologist for the varied constituents of water; the mineralogist for the analysis of fossil productions; the geologist for curbing his flights of theoriz ing fancy, and bringing his speculations within the pale of probability; and the botanist, or vegetable physiologist, for investigations of the food of plants, and the various changes produced on it from its absorption, till it is formed into leaves, bark, wood, or pith. In the great department of animated nature, chemistry is no less indispensable in examining the interesting facts connected with nutrition, respiration, nervous energy, and the various products of animal bodies. Yet these are nothing more than a few brief and necessarily imperfect hints of the varied connections of chemistry with physical knowledge. To give a similar sketch of the dependence of art and industry upon chemical science, would require a volume rather than a page. We may be permit ted, however, to mention two extensive branches, in which an accurate practical acquaintance with chemistry is indispensable we mean medicine and metallurgy, including, under the latter, all the varied processes of art by which metals are worked and fashioned into articles of use or ornament.
Upon all these points Dr. Turner has given valuable details, in a very superior style of seientific composition, uniting, however, with his technical language, much less than we could have wished of the perspicuity and plainness of a merely popular work, but keeping a happy medium between brevity and diffuseness. Comparing it with other English works on Chemistry, it comes nearest in size and plan to the Elements of Henry, or the System of Mur ray, but from the daily and rapid progress of chemistry, and the continual succession of new facts, and of discoveries which alter the whole aspect of the science, books of this kind become gradually less valuable. The works now named, indeed, as well as the other standard works on chemistry, are, for the most part, subjected to important modifications in each successive edition; though it must be obvious that this method of keeping pace with the progress of science, has many disadvantages, and is much akin to the attempt to render an old tree young, by engrafting upon it fresh branches, which are always more likely to fail than to succeed. It must frequently happen, also, that the author may be unwilling or unable to make changes in his arrangement to the extent which is required, in order to keep pace with the progress
of discovery; and hence it is that notes and appendices are multiplied to the certain confusion of the student, and the injury of the work, in simplicity and perspicuity of arrangement. In this point of view we are bound to consider another very able work—
Dr. Ure's Dictionary of Chemistry," which, though different in arrangement, comes into close comparison with the work before us, both with respect to size and the class of readers for whom it is designed. Had Dr. Ure composed the Dictionary ab initio, we feel convinced that excellent as he has rendered it, he could have made it more worthy of approbation than it was possible to do with the Dictionary of Nicholson to work upon, in which it was requisite not only to have the whole of the old matter revised, that obsolete and refuted theories might be expunged, and more accurate and enlarged views inserted in their room, but to draw up a very great number of articles entirely new, of which the original Dictionary contained not even a hint. For the interest of chemistry, it is to be lamented that a man so able as Dr. Ure to do justice to the subject, was put upon the execution of this laborious and ungracious task. In all this Dr. Turner's work possesses most important advantages over its elder competitors, and the author has availed himself of them most amply; for it may be justly said to contain as complete a picture of the present state of chemistry in all its branches, as it was practicable to delineate within the bounds of a moderate volume.
To us, however, after a careful examination of his arrangement, and his method of treating the individual parts of his subject, there appears to be a considerable want of the simplicity requisite in a work intended for students beginning the science. For those who have already made some progress in chemical knowledge, the work is much more adapted, both as a book of study and of ready reference, upon the facts and principles which have been long established or recently discovered. For such purposes, we could not desire a better instructor than Dr. Turner; but this is as far as we can go in our estimation of his merits, for as an initiatory work, or first book on chemistry, we do not think its plan judicious, and feel assured that it will wear a repulsive aspect to the greater number of young men, who may peruse it with such a notion of its character. It may be remarked, accordingly, that the high praise which the work has obtained, and, unquestionably, well merits, has come from chemists who are capable of judging of its comprehensiveness and accuracy, and from students who, having acquired, by means of lectures or more elementary books, a certain acquaintance with chemical facts and chemical language, find Dr. Turner an admirable guide in their further progress. The title, indeed, of "System," would, in our opinion, be much more appropriate than 'Elements. We are aware that the author expressly says, the work is designed for persons who have attended, or are attending, Lectures on Chemistry;' but he must know well that the latter
class in particular require something more simple and attractive than they will find in his Elements. He begins, for example, with the usual queue of metaphysical generalities respecting matter, extension, impenetrability, mobility, &c., which he goes on to explain thus:35952226 alone offr
• Extension is the property of occupying a certain portion of space. A substance is said to be extended when it possesses length, breadth, and thickness. By impenetrability is meant that no two portions of matter can occupy the same space at the same moment. Every thing that possesses extension and impenetrability is matter.'-p. 1.
Now we humbly submit, that though this manner of commencing a work on physical science can boast of the authority of the highest names, yet it is exceedingly repulsive, if not unintelligible, to young men commencing the study. Nay, he has not made the best, even of this plan, bad as we conceive it to be; for, in proceeding to explain the extreme divisibility of matter, he quotes Nicholson's Illustrations of the Extensibility of Gold, which is a mechanical, not a chemical example, and contents himself with saying, by chemical means, a still more minute division may be effected.' (p. 2). Now we may justly ask, why, in this case, Dr. Turner did not introduce a plain, easy, chemical experiment, rather than the inappropriate example from Nicholson? He tells us in his preface, that he wishes to make the student intimately acquainted with the theory, at the same time that he is acquiring a knowledge of the facts of chemistry, so that, by the establishment of fixed principles, the details may more easily be impressed on the memory, and excite an interest which they could not otherwise possess.
With due deference to the professor of chemistry, we are clearly of opinion, that this is an attempt to lay the foundation of an edifice in the air, and build downwards. It is the details and facts which alone can be learned; in the first instance, whatever attempts may be erroneously made to give the theory and the general principles a priority, because of their presumed importance. Does Dr. Turner require to be told, that every general is made up of particulars? and, consequently, that facts and details must always form the only foundation for principles and theories? He might as well endeavour to teach a manufacturer to bleach a piece of Irish linen, or dye a piece of silk green, by telling him generally, that a chemical substance has various affinities with other chemical substances, as to impart any real knowledge of the science by teaching what he calls fixed principles, while he makes the facts and the details a subsequent and minor consideration. Such remarks, to some, may appear too minute and hypercritical, but when authors will disregard the first principles of logic, we must remind them that they are amenable to its laws.
The work is divided into four parts, treating, in succession, of im
ponderable substances Inorganic Chemistry; Organic Chemistrygm and Analytical Chemistry, with an Appendix, containing certain tables. On each of those divisions, we shall now make such remarks as were suggested on perusing them.
The sections on electricity and galvanism, have been, the author informs us, very materially altered; but it strikes us forcibly, that though well written and interesting, they have more the air of historical sketches than of an elementary didactic treatise. If Dr. Turner composes his lectures upon these subjects according to this plan, he cannot hope to make his pupils good chemical electricians or galvanists. We are much better pleased with his sections on caloric and light, though these again are too much like a dissertation, or a monograph. We select, as a favourable specimen of his manner, his remarks on the vapours of metals, earths, &c., supposed to be diffused in the atmosphere.
It has accordingly been supposed, that the atmosphere contains, diffused through it, minute quantities of the vapours of all the bodies with which it is in contact; and this idea has been made the basis of a theory of the origin of meteorites. But this doctrine has been successfully combated by Mr. Farraday, in his Essay on the Existence of a Limit to Vaporization, published in the Philosophical Transactions for 1826. The argument employed by Mr. Farraday, is founded on the principle by which Dr. Wollaston has accounted for the limited extent of the atmosphere. Since the volume of gaseous substances is dependent on the pressure to which they are subject, the air in the higher regions of the atmosphere must be much more rare than that in the lower, because the former sustains the pressure of a shorter atmospheric column than the latter; so that in ascending upwards from the earth, each successive stratum of air, being less compressed than the foregoing, is likewise more attenuated. Now it is found experimentally, that the elasticity or tension of any gaseous matter diminishes in the same ratio as its volume increases; and, accordingly, whenever the tenuity of a portion of air, owing to its distance from the earth's surface, or any other cause, is exceedingly great, its tension is exceedingly small. Reasoning on this principle, Dr. Wollaston conceives that at a certain altitude, probably at a distance of 40 or 50 miles from the surface of the earth, the rarefaction and consequent loss of elastic force is so extreme, that the mere gravity of the particles becomes equal to their elasticity, and thus puts a limit to their separation.
What Dr. Wollaston suggests of aerial particles, Mr. Farraday supposes to occur in all substances; and this supposition is perfectly legitimate, because gaseous matter in general is subject to the same law of expansion, and is likewise under the influence of gravity. He infers that every kind of matter ceases to assume the elastic form whenever the gravitation of its particles is stronger than the elasticity of its vapour. The loss of tension necessary for effecting this object may be accomplished in two ways, either by extreme dilatation or by cold. For substances of great volatility, such as air and most gases, the former is necessary; because the degree of cold which we can command at the earth's surface diminishes their tension in a degree quite insufficient for the purpose. But the volatility of innumerable bodies is so small, that their vapour at com