The velocity of the stream is the only criterion of authority we have; inaccuracies and misstatements may have unavoidably occurred; but whatever was subjected to measurement, is given with confidence.

Thus much for this undertaking. Its merits, its principles, and its utility, may be called in question. In point of magnitude it has few rivals; and the reflecting mind, while it censures its defects, allows its Author to say with the poet, Exegi monumentum ære perennius Regalique situ Pyramidum altius ;

Quod non imber edax, non Aquilo impotens
Possit dirue, aut innumerabilis

Annorum series, et fuga temporum.

Non omnis moriar, multaque pars mei
Vitabit Libitinam.

ART. XII. Report of Mr. Brande's Lectures on Mineralogical Chymistry, delivered in the Theatre of the Royal Institution, in the Spring of 1817.

[Continued from page 73.]

IRON is a metal so generally diffused throughout nature, that

there are comparatively few fossils which can be said to be perfectly free from it. It is confined to no particular formation or series of rocks, but pervades primary, transition, secondary, and alluvial strata. Water often holds one or more of its saline combinations in solution, and thus forms chalybeate springs; and vegetable and animal bodies afford more or less of it when submitted to the processes of analysis.

The proper ores of iron are also very numerous, and it exists in so many combinations with other bodies, that it often becomes very difficult to say what should be regarded as the characteristic ingredient.

These considerations alone, render the subject now before me of much interest to the mineralogical and analytic chymist; and when we reflect upon the circumstances connected with it, the

history of iron assumes an importance which might justly entitle it to be distinguished as the king of the metals. It is the principal metallic ingredient in those lapideous masses, which in different countries have fallen upon our globe, and which have been termed meteoric stones. Though we really know nothing of the source or origin of these bodies, it has been ascertained upon the most satisfactory and indisputable evidence that they are not of terrestrial formation, and consequently, since men began to think and reason correctly, their visits to our planet have awakened much speculation, and some experimental research.

In the first place, it deserves to be remarked, that we have a very distinct evidence of the falling of stony bodies from the atmosphere in various countries, and at very remote periods. For, to say nothing of the fabulous trash which encumbers the annals of ancient Rome, or the extended catalogue of wonders flowing from the lively imagination of Oriental writers, such events are recorded in holy writ, and have been set down by the most accredited of the early historians; and although philosophic sceptici m long contended against the admission of the fact, it has in modern times received such unanswerable proofs, as to be allowed by all who have candidly considered the evidence, and is only rejected by the really ignorant, or by those who, for the sake of singularity, affect disbelief.

The first tolerably accurate narration of the fall of a meteoric stone, relates to that of Ensisheim, near Basle, upon the Rhine. The account which is deposited in the church was thus: A. D. 1492, Wednesday, 7 November, there was a loud clap of thunder, and a child saw a stone fall from heaven; it struck into a field of wheat, and did no harm, but made a hole there. The noise it made was heard at Lucerne, Villing, and other places; on the Monday King Maximilian ordered the stone to be brought to the castle, and after having conversed about it with the noblemen, said the people of Ensisheim should hang it up in their church, and his Royal Excellency strictly forbade any body to take any thing from it. His Excellency, however, took two pieces himself, and sent another to Duke Sigismund of Austria. This stone weighed 255 lbs.

In 1627, 27th November, the celebrated Gassendi saw a

burning stone fall on Mount Vaisir, in Provence; he found it to weigh 59 lbs.

In 1672, a stone fell near Verona, weighing 300 lbs. And Lucas, when at Larissa, 1706, describes the falling of a stone, with a loud hissing noise, and smelling of sulphur.

In September, 1753, De Lalande witnessed this extraordinary phenomenon, near Pont de Vesli. In 1768, no less than three stones fell in different parts of France. In 1790, there was a shower of stones. near Agen, witnessed by M. Darcet and several other respectable persons. And on the 18th of December, 1795, a stone fell near Major Topham's house in Yorkshire; it was seen by a ploughman and two other persons, who immediately dug it out of the hole it had buried itself in; it weighed 56 lbs.

We have various other and equally satisfactory accounts of the same kind. All concur in describing a luminous meteor moving through the air in a more or less oblique direction, attended by a hissing noise, and the fall of stony or semimetallic masses, in a state of ignition. We have however evidence of another kind, amply proving the peculiarities of these bodies. It is, that although they have fallen in very different countries, and at distant periods, when submitted to chymical analysis they all agree in component parts; the metallic particles being composed of nickel and iron; the earthy of silex and magnesia.

Large masses of native iron have been found in different parts of the world, of the history and origin of which nothing very accurate is known. Such are the great block of iron at Elbogen in Bohemia; the large mass discovered by Pallas, weighing 1600 lbs. near Krasnojark in Siberia; that found by Goldberry, in the great desert of Zahra, in Africa; probably also that mentioned by Mr. Barrow, on the banks of the great fish river in Southern Africa; and those noticed by Bruce, Bougainville, Humboldt, and others in America, of enormous magnitude, exceeding 30 tons in weight. That these should be of the same source as the other meteoric stones, seems at first to startle belief; but when they are submitted to analysis, and the iron they contain found alloyed by nickel, it no longer seems credu

lous to regard them as of meteoric origin. We find nothing of the kind in the earth.

To account for these uncommon visitations of metallic and lapideous bodies, a variety of hypotheses have been suggested. Are they merely earthy matter fused by lightning? Are they the offspring of any terrestrial volcano? These were once favourite notions; but we know of no instance in which similar bodies have in that way been produced, nor do the lavas of known volcanos in the least resemble these bodies, to say nothing of the inexplicable projectile force that would here be wanted. This is merely explaining what is puzzling, by assuming what is impossible; and the persons who have taken up this conjecture, have assumed one impossibility to account for what they conceive to be another, namely, that the stony bodies should come from any other source than our own globe.

The notion that these bodies come from the moon, though it has been laughed at as lunacy, is, when impartially considered, neither absurd nor impossible. It is quite true, that the quiet way in which they visit us is against such an origin; it seems, however, that any power which would move a body 6000 feet in a second, that is, about three times the velocity of a cannon ball, would throw it from the sphere of the moon's attraction into that of our earth. The cause of this projective force may be a volcano, and if thus impelled, the body would reach us in about two days, and enter our atmosphere with a velocity of about 25000 feet in a second. Their ignition may be accounted for, either by supposing the heat generated by their motion in our atmosphere sufficient to ignite them; or by considering them as combustibles, ignited by the mere contact of air.

While we are considering the possibility of these considerations it may be remembered, that in the great laboratory of the atmosphere, chymical changes may happen, attended by the production of iron and other metals; that at all events such a circumstance is within the range of possible occurrences; and that the meteoric bodies which thus salute the earth with stony showers, may be children of the air, created by the union of simpler forms of matter. The singular relationship between iron and nickel, and magnetism and the uniform influence of meteoric

phenomena upon the magnetic needle, should be taken into the account in these hypotheses.

The existence of masses of native iron has led me to these questions, which, lest they should be deemed irrelevant, I will pursue no more.

The ores of iron may be classed under three divisions, of which the first includes chiefly mineralogical curiosities, such as arseniate, chromate, phosphate, and a few other rare combinations.

The second embraces the sulphurets of iron, of great use in affording some of the saline combinations, such especially as green vitriol or copperas. These ores are known under the name of Pyrites. Black or magnetic pyrites contains 63 iron +37 sulphur. Yellow or common pyrites consists of 46 per cent, iron + 54 sulphur.

This is abundant all over the world. Large crystals have been found in the graves of the Incas of Peru, and seem to have been used as mirrors. Globular masses of it occur in chalk. Some varieties are very liable to decomposition, and consequently often mischievous in a mineralogical cabinet.

The most interesting ores of iron are those in which the metal is united to oxygen. These are the sources of the enormous quantities of this body that are called for in commerce. There are two oxides of iron, which have been termed the black and the red; the one consisting of 100 iron +30 oxygen, and the other of 100 iron +45 oxygen. They both occur native; the former principally in primitive, the latter in secondary rocks.

Magnetic iron ore is one of the purest varieties of the protoxide of iron; the fine bar iron of Dannemora is made from it; but it is not the ore used in England, though found in Cornwall, Devonshire, and the Shetland Isles. It not only attracts the magnet, but is itself often polar. It occurs massive and variously crystallized, its primitive form being the octohedron.

Specular iron ore, or iron glance, is a variety of this oxide; it is very slightly magnetic. The mines of Elba, which have been worked for 3000 years, afford magnificent specimens ; it is easily distinguished from magnetic iron by affording a red and not a black streak, when rubbed on paper.