It is essential to have a correct understanding respecting this term scorification. We know that when a bath of impure castings is kept in fusion in contact with the air, the iron is oxidized as well as certain bodies which are associated with it, of which silicium is the most important. The oxidation gives rise to a ferruginous silicate, which occupies the upper part of the metallic bath. This is a true liquid scoria; in cooling it will at first become doughy, then solid; and in the latter state will present a compact lithoidal crystalline structure; one wholly different, in a word, from the spongy and tufaceous substances to which we give the name of volcanic scoriæ. The former and metallurgic sense is that in which we understand the scorification of the globe. As to the feldspathic rocks, many geologists consider that they have not been produced simply by the dry way, as we have just shown has been probably the case with the deep peridotic beds, but that they have been formed by the intervention of particular agents, among others of water. However this may be, we may here find, especially in the trachytes, the other extreme term of the series of masses silicated in the general scorification. The opposition between these two types, the most distinct and the best characterized, bears not only on the mineralogical composition and the circumstances of crystallization, but also on the density of these masses and their situation at depths necessarily very different. Let it be remarked further that this primitive scorification, extending through a thickness so considerable, may, even at the existing epoch, present, according to the depth, masses in the three states of which we have been speaking-solid, viscid, or liquid. If metallic iron, quite habitual in meteorites, is wanting in terrestrial rocks, this difference may simply result from the circumstance that in our globe, where the oxygen of the atmosphere is in excess, the oxidation may have been complete and have left no metallic residue. When, however, we say that the terrestrial masses contain no native iron it is evident that the question only regards those which eruptions render accessible to our investigations; masses which, in view of the great dimensions of our planet, form but a sort of coating. There is nothing to prove that below those aluminous masses which have furnished, in Iceland, for example, lavas so analogous to the type of the meteorites of Juvinas, that below our peridotic rocks to which the meteorite of Chassigny so closely approximates, there do not exist lherzolithic groups in which native iron begins to appear; groups, that is to say, similar to the meteorites of the common type; then, going still lower, types more and more rich in iron, of which the meteorites offer us a series of increasing density, from those in which the quantity of iron represents nearly half the weight of the rock to the massive iron itself. Seme facts might, perhaps, be brought to the support of these views. Thus, platina, which its great density had probably placed, at the beginning, in profound regions, has, according to M. Engelhardt, been found associated with native iron. At all events, this last metal is allied to iron in a proportion which exceeds 10 per 100, and which suffices to render it strongly magnetic. It may be added that if, in the Ural, platina has never been found in place, it is often incrusted with chromate iron, and that it has even been met with still engaged in fragments of serpentine. By this association, therefore, this metal seems to convey to us a new proof of the existence of magnesian rocks of the peridotic family, at considerable depths. ABSENCE IN THE METEORITES OF STRATIFIED ROCKS AND OF GRANITE. Meteorites, so analogous to certain of our rocks, differ considerably from most of those which form the terrestrial crust. *G. Rose, Reise nach Ural, t. ii, p. 390. Le Play, Comptes Rendus de l'Académie des Sciences, 1846. The most important difference consists in the fact that, in the meteorites, nothing has been found which resembles the materials that constitute the stratified formations-neither arenaceous rocks, nor fossiliferous rocks; that is to say, nothing which testifies to the action of an ocean on these bodies any more than to the presence of life. A great difference is manifested, even when we compare the meteorites with the terrestrial rocks not stratified. Never has there been met with in the meteorites either granite, or gneiss, or any rocks of the same family which form, with these, the general layer on which rest the stratified formations. We do not even observe there any of the constituent minerals of granitic rocks-neither orthose, nor mica, nor quartz-any more than tourmaline and other silicates which are associates of those rocks. Thus, the silicated rocks which form the envelope of our globe are wholly wanting among the meteorites. It is, as has been seen above, in the deeper regions only that we must seek the analogues of these latter; in those basic silicated rocks which only reach us in consequence of eruptions by which they have been expelled from their primitive repository. In every point of view, the absence in meteorites of the whole series of rocks which constitute, to so great a depth, the crust of the earth is a circumstance well calculated to arrest attention, whatever may be the cause. This absence may be explained in different ways; whether it be that the meteoric fragments which reach us do but proceed from the internal parts of planetary bodies constituted like our globe; or whether these planetary bodies themselves are deficient in silicated quartziferous or acid rocks as well as in stratified formations, In this latter case, which is the most probable, they must have passed through evolutions less complete than the planet we inhabit; and it is to the co-operation of the ocean that the earth has owed, in its origin, its granitic rocks, as it has owed to the same agency, at a later period, its stratified deposits. GENERAL OBSERVATION. In fine, the privilege of ubiquity pertaining to peridot, as well in our deep subjacent rocks as in the meteorites, is explained, as the preceding experiments show, by the fact that it is in some sort the universal scoria. It may be concluded from what precedes that oxygen, so essential to organic nature, must also have played an important part in the formation of the planetary bodies. Let us add that without oxygen we can conceive of no ocean, nor of any of those great functions, whether superficial or profound, of which water is the cause. We thus touch on the foundations of the history of the globe, and draw closer the bonds of relationship, already disclosed by the similarity of their composition, between the parts of the universe whose nature it is given us to know. APPENDIX. DEVELOPMENT OF THE COLLECTION OF METEORITES OF THE MUSEUM. For the thorough study of meteorites it was indispensable to possess a collection in which the descents which have occurred in different countries should be represented in as complete a manner as possible, and in which they might be examined and compared with one another. For this reason it is proper to say a few words on the development of the principal collection of France. Specimens of divers meteoric descents had already been annexed to the museum. With a view of developing this rising collection, I made an appeal, which has been heard in Europe and in different other regions of the globe, by numerous persons desirous of promoting science. In 1861 the specimens, representing 53 falls, amounted in number to 86, weighing altogether 691 kilograms. On the 30th of March, 1868, at which time a new and detailed catalogue was published, the number of falls represented, embracing the discoveries of meteorites of incontestable origin but unascertained date, was 203; the number of the specimens exceeded 550, and formed a weight of 1,682 kilograms. This collection, arranged at first in chronological order, has recently been classified methodically, in conformity with the principles of classification given above. 3, 154 74) 20 83 37 74 *382 *1,080 Lockport, (Cambria,) New York.... Burlington, (Otsego county,) New York. Guilford county, North Carolina... Bohumilitz, Bohemia Claiborne county, Alabama.. Cocke county, (Sevier,) Tennessee Scriba, (Oswego county,) New York.... Carthage, (Smith county,) Tennessee.. *1, 237 1811. 8 1814. Bitburg, Eifel... 9 1814, (1815) Lenarto, Hungary. 10 1818.. 281 The total number of stone falls represented is 47, of which the largest specimen in the collection is one which fell at Weston, Connecticut, December 14, 1807, weighing 36 pounds, (16 kilos.) The number of iron localities is 56; the |