But to pursue the details of our researches, we remark, that the bed, No. 7, which forms so interesting a feature in the Claiborne section, is exhibited in many other places, and often becomes an important criterion to determine other parts of the series. Two miles below, near Forward's landing, it makes its appearance in a similarly elevated cliff, and becomes quite as interesting for the abundance of its fossils, with no apparent diversity of species. And again, still farther down the river, at Barefield's plantation, it is developed about ten feet above the water, in connection with the subjacent oyster bed.

Four miles farther south, at the bend of the river, near limestone creek, the bed, No. 7, appears at low water in connection with the overlying Claiborne beds. It also occurs in the interior of Clark county, where it is exposed in a ravine at the base of the white limestone hill; on Limestone creek, near the salt works, and at the base of St. Stephen's bluff one mile above the landing: thence in a northeasterly direction, its outcroppings may be traced to the borders of Mississippi.

In all these situations, the stratum under consideration exhibits a remarkable identity both in its mineral and zoological characters; it also retains its parallelism with the exception of the two first localities, where its uncommon elevation may be attributed to the unevenness of the older cretaceous beds which it overlaps in a tortuous and irregular manner.

The remaining part of the eocene series, exclusive of the superficial sand and clay, may be included under the appellation of white limestone. The peculiarities of this part of the series, seem to require such a distinction. It consists of limestone, both compact and loose, somewhat arenaceous and marly below, but passing upwards into a very pure carbonate of lime, having often a white chalky appearance without signs of stratification. But the distinction regards more especially its fossils. Though the general type of its fauna identifies it as a part of the eocene group, yet there is a manifest peculiarity; the upper portion especially consists almost entirely of comminuted remains of marine organisms, such as Orbitolites and other coralline forms. Indeed the aspect of the species in the subordinate part of the formation presents obvious differences, such as occurrences of Echinoderms of various genera, pectens and oysters of a peculiar type, and above, a very unique species of cetacean mammal. These peculiarities were, until lately, considered a sufficient reason to class these deposits as a newer part of the cretaceous system. But it is now ascertained both by stratigraphical and paleontological evidence, that they form an upper section of the eocene strata. We have fixed the commencement of this subdivision immediately after the bed last considered, No. 7, for here we find an evident transition from the prevailing forms of the preceding beds

to a peculiar zoological type that marks a very evident change of geological condition.

With a few of the smaller less characteristic species that have passed into these upper beds, we meet with a large proportion of Radiata, such as Scutella, Spatangus, &c., and as we ascend in the series, various new species of pecten and oysters, to the almost entire exclusion of the species that prevailed in the preceding deposits.

The ferruginous sand which we regard as the transition bed, is not very distinguishable from the bed immediately preceding, except for the large number of Scutella which it contains. Six miles below Claiborne at the bend of the Alabama, it may be seen with a large amount of its characteristic fossils, where the superjacent strata are identical with those similarly associated in the Claiborne section. But the series are continued upwards so as evidently to connect with the Orbitolite limestone, and a few miles down the river near Dale's ferry, a similar connexion may be seen with a very full development of the Orbitolite limestone. Many other instances of this kind might be adduced if it were necessary to show that such is the true order of the series.

The white limestone formation is exhibited in detached and uneven masses, constituting a prominent feature of the counties of Munroe, Clark and Washington. In the neighboring counties, and even through the state of Mississippi, the white limestone is replaced by a blueish argillaceous marl, in some instances loose, in others hard and compact. After the white limestone was deposited, new agencies appear to have been brought into operation, which furrowed out its beds, and, in many instances, laid bare even the lowest of the subjacent strata. These effects are more manifest in the northern limits of Clark county, where the denudations have extended to the lowest eocene beds and formed ravines between the limestone hills in some instances to the depth of three or four hundred feet. These are the only marked effects of violent disturbance that occur in any part of the series, and they very probably belong to a much later date, perhaps to that change of geological_conditions indicated by the overlying mass of sand and clay. But whether this superficial mass was formed within or after the eocene period, we have not the means of knowing, as it is destitute of fossils. The gravel and rolled shingle however seem to indicate a kind of agency more in accordance with events of some subsequent date, than with that of the tranquil deposition of the preceding eocene strata.

The train of these remarks has caused us to omit noticing the paleontological features of the white limestone formation. The orbitolite and other coralline remains which constitute its principal ingredients have already been alluded to. Their accumulation here furnishes a striking illustration of the remark, "That

the most important results are often produced by the simplest means." For what can seem more insignificant than one of these small discoidal organisms more attenuated than the thinnest paper? or the still smaller coralline forms scarcely distinguishaable from a microscopic fibre? But insignificant as they appear in a separate point of view, they constitute the entire mass of many of these limestone hills.

In addition to this mass of zoophytes, may also be noticed various species of Echinoderms, some of which are quite unique; they belong to the genera, Spatangus, Scutella, and Echinus. One species of Spatangus is very similar to S. retusa, a cretaceous fossil.

It may be presumed, from this similarity of fauna, that the conditions in which the two formations were produced, could not have been very different. If the Mississippi equivalent of the white limestone, which is a bluish marly limestone, were taken for the type, it must be admitted that a striking similarity also exists even in their mineral character.

The molluscs peculiar to these beds are Spondylus dumosum, Pecten Poulsoni, P. perplanata, Ostrea panda, O. cretacea, and indeterminate casts of Cyprea, Conus, Natica, Mya, and Modiola. The remains of fish are principally of the Placoid order, as the ray, shark, and pristis. But the most wonderful of all these associated tribes, is the noted cetacean called the Zeuglodon.

The metropolis of this strange inhabitant appears to have been the tertiary of Alabama. For here principally the relics abound. They are scattered more sparingly in a westerly direction as far as the state of Arkansas, and eastwardly to South Carolina. Their geological situation is in the tertiary beds immediately below the orbitolite limestone, near the denuded surface of those gentle declivities which form a step to the summit of these hills. They are seldom found in their natural position-but in many instances appear to have been torn, by some disturbing cause, from their ancient resting place and scattered to remote distances. We are informed by some of the early settlers that entire skeletons were formerly exposed upon the surface of the earth, and that these remains were in some instances so abundant as to become an encumbrance upon the plantations. We obtained a vertebra of this animal from the white limestone strata of the Claiborne section; and the fragment of another from a similar section near Forward's landing. We also obtained a large portion of the vertebral column in the western part of Clark county; and the lower maxillæ, teeth and other fragments of the head, near Bucatunnie creek, Mississippi.*

We omit here some descriptive remarks on the Zeuglodon, as the skeleton has been elsewhere described with more fullness.-EDs. SECOND SERIES, Vol. VI, No. 18.-Nov., 1848.

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These eocene strata were all evidently formed in circumstances exempt from the influence of disturbing causes. With the exception of a few local interruptions of level, attributable to the inequalities of the older beds, they appear to retain their parallelism in all their geographical extent. It is very rare that in remote situations, a diversity in the sea-bottom, or some other geological change, does not produce a marked diversity in the character of the deposits; but this series furnishes a remarkable exception in this respect. A striking uniformity in the lithological and zoological characters of the same beds, prevails wherever they have been observed. This uniformity evinces not only the absence of disturbing causes, but a very unusual coincidence of geological conditions. The denudation of the white limestone beds, being considered as a subsequent event, is of course not included in this category.

Another circumstance, worthy of consideration, is the absence of land and fluviatile testacea, and the exclusive limitation of the fossils of these beds to a marine fauna, with the exception of the few remains of terrestrial animals already noticed. Even the estuary group of Cerithia so numerous in the European equivalents, is very sparingly represented in these deposits.

Restricted as these beds are to a marine fauna, it is rather surprising that they contain a very considerable abundance of vegetable remains. Nothing very precise however has been ascertained respecting the situation of the land from whence these remains were derived. It is evident however that this part of the globe, in the period under consideration, was very different from what it is at present.

From the general character of the organic remains, as well as from various other considerations, it is not likely that these deposits were formed in very deep water. We may rather conclude, from the indications exhibited, that they were at one time sedimentary shoals, or a mud-bank, forming a suitable habitation for the Acephala and other organisms that cannot live in the open ocean; and at another time that this body of water was so changed as to become expanded into a widely extended ocean, with a corresponding change of fauna, suited to its varying zones of depth, either such as were adapted to inhabit a shallow deepening sea, or the still greater depths of a more expanded ocean.

Taking into view the regular and quiet operation of the agencies which mark the progress of events in the series, it is rather surprising, at first, to notice the contrast exhibited between this and the preceding cretaceous group; the peculiarity of its organic remains, gives to the tertiary fauna more the appearance of a new creation than a gradual development of the same general system. But as the upper portion of the cretaceous equivalents

is probably wanting in our series, and possibly some other intervening deposits not yet made out, a sufficient time may have. elapsed between the deposition of the two groups, to furnish a partial explanation of the remarkable change of conditions they manifest.

ART. XXXV.-On the Oxydation of Uric Acid by means of Potassa and Ferridcyanid of Potassium; by ADOLPH SCHLIEPER.

ALTHOUGH a great many products of the decomposition of uric acid have been discovered during the last ten years, yet they were nearly all obtained only by the oxydating influence of acids or acid bodies. The oxydating action of brown oxyd of lead and nitric acid on uric acid has been investigated by Liebig and Wöhler in a masterly manner.* I have already demonstrated the formation of alloxan and urea from uric acid, by the action of chlorate of potassa and hydrochloric acid. With these exceptions, the influence of no other oxydating body on uric acid, has ever been the subject of an original investigation. For these reasons it seemed to me interesting, to study the oxydation of uric acid in an alkaline solution, because its decomposition, effected altogether by a new mode, might throw light on many points, still enigmatical, in the constitution of the products of the decomposition of uric acid.

A notice from Mercer, in regard to the bleaching of cotton cloth dyed indigo-blue, by means of a solution of caustic potash and ferridcyanid of potassium, suggested to me the idea of applying the same mode of oxydation to uric acid; but in doing so, I found it exceedingly difficult, to separate the resulting salts of potash in such a way, that the newly generated and so easily decomposable products of uric acid should remain unchanged.

It is well known that one equivalent of ferridcyanid of potassium with one equivalent of potash are decomposed in presence of oxydizible substances, in such a manner, that the red prussiate of potash takes up one equivalent of potassium, forming with it two equivalents of ferrideyanid of potassium, during which the oxygen of the potassa set free combines with the oxydizible body.

Ferridcyanid of potassium 3KCy+Fe, Cy,=3KCy+Fe,Cy2 +Cy with potassa (K+0) two equivalents of prussiate of potossa 4KCy+ Fe, Cy, and one equivalent of oxygen.

=

* Annalen der Chemie und Pharmacie, Band 26, p. 241.