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these animals as the effect of the Mosaic deluge. Nor is the objection, in its origin, so much directed against the insulated supposition that these organic remains are immediate proofs of the Mosaic deluge; as against the principle of supporting the credibility of the sacred Scriptures on any unascertained interpretation of physical phenomena. Such a support appears to be imprudent, as well as unnecessary: uunecessary, because the moral evidence of the credibility of the Scriptures is of itself fully sufficient; imprudent, because we have the strong ground of antecedent analogy, not only in another but in this very branch of knowledge, for anticipating a period in the progress of science, when particular phenomena may be interpreted in a very different manner from that in which they are intepreted at present. Thus the explanation of the motions of our solar system, which is now admitted very generally, without any fear of weakening the authority of Scripture, was once as generally impugned on the principle of that very fear. Time was also, and indeed within the last century, when the shells and other organic remains, which are imbedded in the chalk and other solid strata, were considered to be the remains and proofs of the Mosaic deluge; and yet at the present day, without any fear of injuring the credibility of the Scriptures, they are admitted very generally to have been deposited anteriorly to the Mosaic deluge. And who will venture to say, in the infancy of a science like geology, that the same change of opinion may not happen with respect to the organic remains of the gravel beds and caverns. Nor indeed do I think, and I expressed this opinion nearly twenty years since, that the organic remains of the gravel beds and the caverns can be, on even mere philosophical grounds, adduced as physical proofs of the Mosaic deluge. For as according to the Mosaic record it was the intention of the Deity on that occasion, in the midst of a very general destruction of individuals to preserve species, we should in reason expect, among the organic remains of that catastrophe, a preponderance, at least, of the remains of existing species: since, although some species may have been lost subsequently to the deluge, these naturally would be comparatively few. But the fact is just the reverse; for by far the greater number of the organic remains of the gravel, as of the caverns, belong to species not known now to exist. And with respect to those remains which appear capable of being identified with living species, Cuvier allows that they belong to orders of animals, the species of which often differ only in coulor, or in other points of what may be called their external or superficial anatomy; and cannot therefore be satisfactorily identified by the remains of their bones alone.

I do not consider it right to enter into a more extended examination of the question on the present occasion: but, could it be proved that visible traces of the Mosaic deluge must necessarily exist, arguments might be adduced to show both where those traces ought to be expected, and that they do actually exist. But the deluge itself was evidently

a miracle, or an interference with the laws which usually regulate the operation of second causes: and whoever admits the force of the reasoning, contained in Butler's Analogy of Natural and Revealed Religion, will be disposed to allow that visible evidence of the catastrophe may have been purposely obscured, in order to exercise our faith in an exclusive belief of the moral evidence.

I would not lay undue weight on the negative proof arising from the absence of human remains, although they have been in vain searched for, even in parts of the world to which it may fairly be presumed that the human race had penetrated at the period of the Mosaic deluge but undoubtedly such a negative proof is not without considerable weight; especially when taken in connexion with the theory of a continental geologist, M. de Beaumont, of whose powers of philosophical generalization Professor Sedgwick speaks in language the most expressive. "I am using," he say, "no terms of exaggeration, when I say that, in reading the admirable researches of M. de Beaumont, I appeared to myself, page after page, to be acquiring a new geological sense, and a new faculty of induction."*

After having taken a general survey of M. de Beaumont's observations and views, Mr. Sedgwick alludes to an opinion which he himself had expressed in the preceding year, that what is commonly called diluvial gravel is probably not the result of one but of many successive periods. "But what I then stated," he adds, " as a probable opinion, may, after the essays of M. de Beaumont, be now advanced with all the authority of established truth-we now connect the gravel of the plains with the elevation of the nearest system of mountains; we believe that the Scandinavian boulders in the north of Germany are of an older date than the diluvium of the Danube: and we can prove that the great erratic blocks, derived from the granite of Mont Blanc, are of a more recent origin than the old gravel in the tributary valleys of the Rhone. That these statements militate against opinions, but a few years since held almost universally among us, cannot be denied. But, in retreating when we have advanced too far, there is neither compromise of dignity, nor loss of strength; for in doing this, we partake but of the common fortune of every one who enters on a field of investigation like our own. All the noble generalizations of Cuvier, and all the beautiful discoveries of Buckland, as far as they are the results of fair induction, will ever remain unshaken by the progress of discovery. It is only to theoretical opinions that my remarks have any application." (p. 33.)

Mr. Sedgwick then proceeds to argue that different gravel beds having been formed at different periods, it may happen from the nature of diluvial action, that mixtures of the materials of different beds may occur; and consequently that "in the very same deposite we

* See Prof. Sedgwick's address to the Geolog. Society, 1831, p. 29.

may find the remains of animals which have lived during different epochs in the history of the earth." (p. 33.)

He then shows how, from the double testimony of the widely existing traces of diluvial action, and the record of a general deluge contained in the sacred Scriptures, the opinion was naturally formed that all those traces were referable to one and the same action: though we ought in philosophical caution to have hesitated in adopting that opinion, because "among the remnants of a former world, entombed in these ancient deposites, we have not yet found a single trace of man, or of the works of his hands." (p. 34.) Lastly, he strenuously denies that the facts of geological science are opposed to the sacred records, or to the reality of an historic deluge; and for himself, utterly rejects such an inference: and argues justly, that there is an accordance between the absence of human remains in these diluvial beds of gravel, and the supposed antiquity of their formation, inasmuch as the phenomena of geology, and the testimony of both sacred and profane history, " tell us in a language easily understood, though written in far different characters, that man is a recent sojourner on the surface of the earth.” (p. 35.)

SECTION VI.

Metals.

THE atmosphere, and the vegetable, and animal kingdoms, being three out of the four general departments of the external world, are most extensively necessary to the welfare, if not to the very existence, of every individual: but even communities of men, in an uncivilized state indeed, have existed, and in some parts of the earth are still existing, without any further aid from the mineral kingdom than that, which the common soil affords to the growth of the food which supports them. But a civilized state of society is the natural destination of man; and such a state of society is incapable of arising or being maintained, without the aid of mineral substances: and this assertion holds more particularly with respect to the metallic species.

In that department of civilized intercourse which exists in the exchange of the commodities of life, what other substance could be an equivalent substitute for gold and silver, or even copper, as a medium of that exchange? In what constant use, and of what immense importance, are some of the commonest metals in agriculture, and in the arts; or for the various purposes of domestic life! Nor have any substances more successfully exercised the powers of the mind, in the discovery or improvement of physical truths; or more largely contributed to the benefit of mankind by the practical application of those truths. We owe it to the researches of philosophy, not only that new and highly valuable metals have been discovered; but that

the general value of the metals previously known, has been advanced by extended and improved applications of their inherent properties, or by the invention of new metallic combinations or alloys.

If a convincing and familiar proof of the extensive application of the metals to the common purposes of life were required, we need only refer to the case of many a common cottager, who could not carry on his daily concerns and occupations without the assistance of several of the metals. He could not, for instance, make his larger purchases, nor pay his rent, without silver, gold, and copper. Without iron he could neither dig, nor plough, nor reap; and, with respect to his habitation, there is scarcely a part of the structure itself, or of the furniture contained in it, which is not held together, to a greater or less extent, by means of the same metal: and many articles are either entirely of iron, or of iron partially and superficially coated with tin. Zinc, and copper, and antimony, and lead, and tin, are component parts of his pewter and brazen utensils. Quicksilver is a main ingredient in the metallic coating of his humble mirror: cobalt and platina, and metals perhaps more rare and costly than these, as chrome, are employed in the glazing of his drinking cups and jugs. And if he be the possessor of a fowling-piece, which commonly he would be, arsenic must be added to the foregoing list, as an ingredient in the shot with which he charges it; for it is arsenic which enables the shot, during the process of its granulation, to acquire that delicately spherical form by which it is characterised. So that the whole number of metals made use of by society at large for common purposes, amounting to less than twenty, more than half of these are either directly used by the mere peasant, or enter into the composition of the furniture and implements employed by him.

In estimating the value of those mineral substances which were considered in the preceding chapter, as applicable to the common purposes of life, their degree of hardness is the property of principal consideration: but, in addition to this, metallic bodies possess some peculiar properties which very greatly increase their value. Thus, under a force acting perpendicularly on their surface, as under repeated blows of the hammer, or compression by rollers, many of them are capable of being expanded to a greater or less extent; some of them to such an extent as to become thinner than the thinnest paper; which property in its various degrees is expressed by the term malleability: others, though not possessing any great degree of malleability, may be drawn out into a wire, sometimes so fine as scarcely to be visible by the naked eye; which property is expressed by the term ductility. All of them are capable of being expanded or contracted in every direction by an increase or decrease of their temperature; the degree of this expansibility, as of its opposite effect, depending on the degree of the temperature. And lastly, in connexion with certain points of temperature, all the metals are capable of existing either in a solid or in a liquid state: and their property

of passing from a solid to a liquid state, in consequence of the agency of heat, is called their fusibility.

Into the detail of the different degrees in which these properties are possessed by different metals, it belongs to the chemist to enter. What we have at present to consider is, the advantage accruing to society from these properties themselves, and from their existence in that particular degree in which they actually do exist in the different metals: to show, for instance, that those metals which possess malleability in a greater ratio than ductility, or ductility in a greater ratio than malleability, are of infinitely greater value than if the converse were true: and so with respect to the property of fusibility. Thus gold, being comparatively scarce, and principally valuable on account of its colour, its resplendency, and its remarkable power of resisting the action of the air, and of various agents which readily tarnish or rust the more common metals, (all which properties reside on the mere surface,) a given quantity of such a metal is consequently more valuable in proportion to the degree of its malleability; because it may be extended over a greater surface: and no metal possesses this property in so high a degree as gold; so that, as far as the eye is the judge, the most ordinary substance may be made to represent the most costly, at a comparatively trifling expense: while in the degree of its ductility, which in gold would be, for general purposes, of little moment, it is inferior to most of the metals.*

Iron, again, is malleable to a degree which renders it most valuable as a material for fabricating all kinds of instruments for mechanical, domestic, or philosophical purposes; and it is capable of being hardened by well known processes sufficiently for the numerous and important works of the carpenter and mason, and the equally important purposes of war, agriculture, and the arts. A greater degree of malleability, in a metal employed for such purposes as those for which iron is usually employed, especially as this metal is very easily corroded by rust, would clearly have added nothing to its practical value: while its degree of ductility, which exceeds that of every other metal, combined with its capability of being hardened in various degrees, occasionally confers a value on it greatly superior to that of gold.

From the difference in the degree of fusibility of different metals, aided by the disposition which they have to unite so as to form an alloy, arises the possibility of covering one metal in a solid state with a superficial coating of another metal in a state of fusion. I am not aware that this method is employed, at least to any extent, in any

It should be kept in mind that this observation is applied to unalloyed or pure gold; for, when alloyed, this metal is capable of being drawn out into a comparatively fine wire. Dr. Wollaston indeed suggested a method of drawing out even pure gold into an exceedingly fine wire, by enclosing it in a mass of a highly ductile mictal, drawing out the mixed metal into fine wire, and disengaging the gold from the metal in which it was enclosed, by any acid which would dissolve the latter without affecting the gold itself.

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