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springs near the eastern base of the great Warm Spring mountain in Virginia. At these and similar localities, the crumbling slates are imbued with the products of the decomposed pyrites, and yield to the infiltering waters a portion of free acid, as well as sulphates of iron and alumina. But what is specially remarkable in the composition of these waters, is the fact, that the proportion of free sulphuric acid present often very greatly exceeds that which the oxidation of the bisulphuret could furnish. This excess Prof. R. proposed to explain in the following way :—While the bisulphuret is subject to oxidation, as above mentioned, a part of the sulphates thus formed, reacting with the organic matter, always present in these rocks, gives rise to sulphuretted hydrogen gas. This again, as recently shown by Dumas, in the presence of air and organic matter, gives birth to sulphuric acid—and thus the additional supply of this acid, formed at the expense of the sulphates, will be imparted to the percolating water.

Of the second, or alkaline springs, Prof. R. stated, that they were found in the same general slaty belt with the others, but always in connexion with those parts which contain more or less carbonate of lime. Instances of these springs are seen in the Grey Sulphur and Dibbrell's springs, as well as many others in Virginia and Tennessee.

The absence of sulphuric acid in these waters is an obvious consequence of the reaction between the carbonate of lime and the acid in passing into the mass. The same reaction giving rise to the evolution of a great amount of carbonic acid, would, as it were, saturate the pores of the slate with this substance, which, in virtue of its large excess, would have power to decompose the sulphuret of sodium, and perhaps other salts present, and thus give origin to the small amount of carbonate of soda, which imparts alkalinity to these waters. The great proportion of silica, in the solid residuum of these springs, may doubtless be ascribed to the solvent power of the alkaline carbonate.

Professors W. B. and R. E. Rogers read a paper

ON THE COMPARATIVE SOLUBILITY OF THE CARBONATE OF LIME AND

THE CARBONATE OF MAGNESIA.

In presenting these results, reference was made to the statement in the standard chemical and geological works of the much greater solubility of carbonate of lime than carbonate of magnesia. This assumed fact has been made the basis of a theory of the origin of the large pro

portion of carbonate of magnesia in the magnesian limestones. It has been supposed that, in a mixed limestone, containing both the carbonates, the relative amount of carbonate of magnesia would be augmented by the action of the percolating water, in consequence of the more rapid removal of the carbonate of lime, and in this way it has been proposed to explain the curious fact of dolomization.

The experiments of the Profs. R., prove that, in water impregnated with CO2, carbonate of magnesia is more soluble than carbonate of lime. Thus, by allowing the slightly carbonated water used in these investigations to filter through a mass of finely powdered magnesian limestone, and collecting the clear liquid, it was found to contain a much larger proportion of carbonate of magnesia in comparison with the carbonate of lime, than corresponded with the amount of these substances relatively in the powdered rock. Again, by agitating briskly a quantity of the powder with the carbonated water in a glass vessel, and then separating the liquid by filtration, it was observed that a larger relative amount of the carbonate of magnesia had been taken up, than of carbonate of lime.

From these experiments, it is inferred that the infiltering rain water, with its slight charge of carbonic acid, in passing through or between strata of magnesian limestone, will remove the carbonate of magnesia more rapidly than the carbonate of lime, and that thus the rock will gradually become relatively less magnesian, instead of being made to approach the condition of a dolomite, as has been maintained.

Profs. R. called attention to the fact that the stalactites in caverns of magnesian limestone contain only minute quantities of carbonate of magnesia. An examination of those in Weyer's cave, in Virginia, had proved that only the milky white opaque stalactites contain a marked amount, and that the sparry transparent kinds are almost destitute of magnesia. It would thus appear that the carbonate of magnesia, in virtue of greater solubility, is carried off by the liquid from which the carbonate of lime is in part deposited.

Prof. W. B. ROGERS appended some remarks upon the connexion between the mode of stratification of the impending rocks, and some conspicuous features of the stalactitic masses. In caves formed in horizontal limestone, without numerous cross fissures, the stalactites are comparatively infrequent and of small extent. Such is the case in the great Mammoth cave of Kentucky. In those which are placed in axes, or in the midst of steeply dipping strata, as is the case with Weyer's cave, the infiltering waters finding innumerable points of access in the roof along the lines of bedding, give rise to an abundant

accretion of stalactites which depend everywhere from the roof, and clothe the walls in rocky drapery. In the cave in question, vast sheets of stalactite are seen stretching from the roof to the floor. These thin parallel plates have the same direction with the divisional planes of the overhanging beds of limestone. Profs. R. traced their formation to the production, in the first place, of a line of stalactites, along the seam or division in the roof. By farther accretion from the water trickling over their surfaces, these would be made to coalesce, and thus the shape of the whole would at length become that of a sheet, or thin mass gradually extending to the floor.

After the conclusion of this paper, the Association adjourned till Monday morning next at 9 o'clock.

WALTER R. JOHNSON, Secry.

Monday Morning, September 25, 9 o'clock.

The Association met agreeably to adjournment, WM.C. REDFIELD, Esq., President, in the chair.

The first business in order was a report of business by the Standing Commmitte, who, through their chairman, proposed :-.

1st. That Asa WHITNEY, Esq., be admitted to membership in the Association, which was adopted.

2d. That Lieut. M. F. MAURY be added to the Committee on the Sediment of the Mississippi river, which was likewise adopted.

3d. That an abstract of each communication submitted to the Association during its sitting, be furnished, by its author, for publication in the proceedings. Adopted.

4th. That a committee of ten be appointed to memorialize the President of the United States, the Heads of Department, and Congress, upon the promotion of science, by adding to each public expedition which may be organized, a number of scientific men, whose observations may tend to this end.

On this last proposition, remarks were made by Dr. HARE, Prof. AGASSIZ, and others.

Professor HARE observed, that our government was more ardent after military renown, than the great mysteries of scientific truth, and that any aid from that source would be extremely difficult to secure. The object of power, it would seem, was to imitate the silken non

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sense of courteous Europe; and that if gentlemen in station could acquire a knowledge of this, their great aim was accomplished. Our central government was extremely remiss, and had, instead of giving to our people an example, upon all occasions, of dependence upon self, its greatest pride was to copy from the stated and almost obsolete theories of the old world, all that pertained to government, as well as that which related to national habits and the advance of science. It was, what he styled, borrowing a mirror to reflect back our own character ; and he hoped the day had arrived when this practice would be put an end to. If in nothing else, let us at least be original in our scientific structures. We have the material, and it should be our pride to build up our own academies. But we were too much wedded to foreign flattery, he feared, to effect this purpose without a struggle. If France, for instance, passed npon us her notice — that is, by faint praise damning us we were intoxicated in a moment, and all our promises to rely upon ourselves, levelled without exception. He admitted that it was necessary to keep up a Navy and a “ Standing Army,” but he thought that in peace, if the officers must needs receive an academy education, that they should not be encouraged in idleness. Let them be usefully employed. West Point turned out yearly a number of well taught, scientific men; and for what purpose? To guide a rudder, or point a gun? He hoped not. Let these, then, be detailed for the service mentioned in the resolution. What else was their education fit for? He trusted that the committee would be importunate in their inemorial, and not rely upon the effect of a mere formal application.

Professor AGASSIz was under the impression that we should rather depend upon our own energies and exertions, than the patronage of government. Science, from time immemorial, was an object of neglect, and if in other countries, where power, revelled in a different element, it should be forgotten, why should it not here? Men of science, to succeed in their operations, must, on the con'trary, be entirely unknown to what we call the “world.” Patronage government is not worth the time consumed in imploring it. We must stand alone, and while enduring neglect, labour the harder. All the governments upon earth will not, in one year, develop as much scientific knowledge, as one humble individual, whose lot is cast in a garret. After some further discussion, the proposition was adopted, and the following gentlemen were appointed by the Association to constitute the committee on said memorial :

Dr. ROBERT HARE, of Philadelphia ; Prof. BENJAMIN SILLIMAN,

of

Senior, of New Haven ; WILLIAM C. REDFIELD, Esq., of New York ; Prof. BENJAMIN PEIRCE, of Cambridge, Mass.; Prof. STEPHEN ALEXANDER, of Princeton ; Dr. ROBERT W. GIBBES, of Columbia, S. C. ; Prof. HENRY D. Rogers, of Boston; Prest. EDWARD HITCHCOCK, of Amherst, Mass.; Prof. Louis Agassiz, of Cambridge ; Dr. SAMUEL G. MORTON, of Philadelphia.

The Secretaries of the Sections of General Physics and of Natural History, severally, made reports of the doings of those Sections on Friday and Saturday last.

Dr. R. W. GIBBES, from the Natural History Section reported the following papers, read and discussed before that Section on Friday last :

On the Forces which have caused the Rupture, Contortion, Depression, and Upheaval of the Superficial Strata of the Earth, by Prof. L. J. GERMAIN.

On Phacops Hausmani, by Prof. S. S. HALDEMAN.

Report on the Sediment of the Mississippi river, by Dr. M. W. DICKESON.

Also the following, read on Saturday, 23d inst:

On Terraces and Ancient River Bars, the Drift, Boulders, and the Polished Surfaces around Lake Superior and Lake Huron, by Prof. AGASSIZ.

On the Black Banded Cyprinidæ, by Prof. AGASSIZ.
On the Cyprinodonts, by Prof. AGASSIZ.

On Acid Springs and Gypsum Deposits of the Onondaga Salt Group, by Mr. T. S. HUNT.

On Rhamnus Lanceolatus, by Dr. T. GREEN.

On the Geography and Geology of the Northern Mississippi, by R. BOLTON.

Prof. SILLIMAN, Jr.'s, Report for Friday and Saturday morning was not received.

The following communication was received from the Society for the Development of the Mineral Resources of the United States :

Philadelphia, June 10, 1848. To the American Association

for the Advancement of Science. It becomes our duty, as it is our pleasure, to announce the formation of a Society, in this city, which has been denominated, “The Society for the Development of the Mineral Resources of the United

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