exist, independent of the GREAT FIRST CAUSE, in whose existence, as it was, and is, and is to come, was to be found the one, the absolutely necessary truth, and that all others were contingent, just so far as He had made them so.

ON THE ZODIACS OF THE ASTEROIDS. BY PROF. J. S. HUBBARD.

Prof. HUBBARD, of the Washington Observatory, stated to the Association that he was then engaged in computing the Zodiacs of the Asteriods. The term Zodiacs, as here applied, he defined as referring to the zone or belt within which are included all possible geocentric positions of the particular asteroid in question: and the object in thus determining these belts was to facilitate researches into the past history of these remarkable bodies; since in most cases, the question of identity of a missing star, with any asteroid, may be settled at once by a simple inspection of the Zodiacs. The method of computation was that proposed by Gauss in the Monatliche Correspondenz, Vol. X., from which Prof. H. quoted the plan of the analytical investigation.

ON THE DECOMPOSITION OF ROCKS BY METEORIC AGENTS, AND ON THE ACTION OF THE MINERAL ACIDS ON FELDSPAR, &C. BY PROFS. W. B. AND R. E. ROGERS.

[An abstract of this memoir may be found in the fifth volume of the American Journal of Science and Arts, p. 401.]

ON THE DECOMPOSITION OF ROCKS BY METEORIC WATER. By PROFS. W. B. ROGERS AND R. E. ROGERS.

In presenting this communication, the fact was stated, that only one or two observations have hitherto been made by chemists, to test, in a direct and conclusive manner, the power of water, at ordinary temperatures, to decompose rocky substances; at the same time, the general fact of such a decomposition appears to have been assumed in explaining the disintegration of mineral masses, and the conveyance of inorganic ingredients into the substance of plants. The experiments have applied to all the principal crystalline minerals, containing alkalies and alkaline earths, amounting to nearly forty species to the principle aggregates, such as granite, gneiss, &c.-to the different varieties of glass-and to various kinds of coal and wood.

These experiments were also of two kinds with each specimen— the one with pure distilled water; the other with water charged with carbonic acid. The mineral, or other matter, being reduced to a very fine powder in an agate mortar, was in small quantity mixed with the liquid, and transferred to a filter of purified paper. One or more drops of the percolating fluid, received on a slip of platinum was gently evaporated to dryness, and the tache resulting was then examined by delicate test paper. In all cases, the residuum from the carbonic acid water, was greater than from the other; but even in the former, with most minerals, a decided alkaline reaction was obtained. By heating the tache gently for a short, and then a longer time, and again strongly by the blowpipe, unequivocal proof was furnished of the presence of potassa or soda-or of lime or magnesia. The liquid from calcareous or magnesian minerals, becomes milky after heatingthe tache from the potash and soda minerals, as for example, the feldspars, lost its alkaline reaction by the first contact of the blowpipe flame-that from the lime was greatly augmented by the first calcination, in consequence of the removal of carbonic acid, and continued intensely alkaline after a prolonged exposure to the heat. The tache furnished by magnesia minerals, such as the serpentines, was much impaired in alkalinity by igniting, but continued to present a decided reaction with the test paper, after long exposure to the heat. In this way the behaviour of the tache was shown to be capable of furnishing a useful auxiliary means of extemporaneous qualitative analysis.

Some experiments were introduced, in which these effects were properly exhibited by powdered glass, mica, and feldspar.

The attention of chemists was especially invited to these phenomena, as having very important bearings, not only upon the decomposition of rocky masses by the action of the percolating rain, but the subsequent introduction of various crystalline minerals in the rifts and cavities of the strata, and as indicating the necessity of some new and better method than that commonly employed, for determining the amount of alkali present in vegetable or other organic matters.

Experiments were also cited, disproving the opinion which appears to be received among chemists, that the feldspars, hornblends, &c., are entirely unacted upon by sulphuric or hydrochloric acids. By exposing these materials in fine powder to prolonged digestion in the acid, even at common temperatures, a partial solution was found to result. Thus 30 grains of potash feldspar, by digestion for twelve hours, in hydrochloric acid, at temperature 60 degrees, lost nearly

one grain, and the liquid furnished chloride of potassium with chloride of aluminum.

ON THE ABSORPTION OF CARBONIC ACID BY LEIBIG'S DILUTE SOLUTION OF PHOSPHATE OF SODA. BY PROFS. W. B. ROGERS AND R. E. ROGERS.

Prof. R. E. ROGERS gave the results of experiments made by himself and brother, upon this subject, by a dilute solution of the common phosphate of soda, containing one grain of the salt to 100 grains of water, referred to in Leibig's work, entitled, "The Chemistry of Food." By a peculiar form of apparatus, furnishing very accurate results, this saline solution has been found to absorb a far larger proportion of carbonic acid, than is attributed to it by Professor Leibig. The amount given by the latter is 138 per cent., while that found by the Professors R. for the solution at 60 degrees, was 207.9 per cent., and at blood heat, 153.05 per cent.

The Section then adjourned to meet to-morrow at 9 A. M.
B. SILLIMAN, JR., Sec'ry.

Friday, September 22, 12 o'clock.

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

The Secretary of the Section of General Physics reported, that the Section had been organized by the appointment of Prof. JOSEPH HENRY, Chairman, and Prof. BENJAMIN SILLIMAN, JR., Secretary, and that a Standing Committee had been appointed for said Section, composed of

Prof. Wm. B. ROGERS, Prof. BENJAMIN PEIRCE, Prof. JAMES H. COFFIN, Prof. B. SILLIMAN, JR., and Prof. JOHN H. C. COFFIN. Also, that Prof. R. E. ROGERS had been appointed Assistant Secretary of the Section.

He also reported, that the scientific proceedings which had taken place in the Section yesterday and this forenoon, were as follows:

Prof. B. SILLIMAN, JR.. reported for the Section on General Physics

That Prof. COFFIN had read a Paper on Winds, being a report on

that subject, compiled in conformity to an appointment made at a previous meeting of the Association of American Geologists.

That a paper had been read by Profs. W. B. and R. E. ROGERS, on the Volatility of Potassa and Soda, and their Carbonates.

That Prof. ALEXANDER had read a paper on Aberration of Light.

The Secretary of the Section of Natural History reported the organization of that Section by the appointment of Prof. LOUIS AGASSIZ Chairman; Dr. R. W. GIBBES, Secretary; Dr. A. A. GOULD, Assistant Secretary: and, in addition to the above, Dr. S. H. DICKSON and Prof. JAMES HALL, as members of the Standing Committee.

Dr. GIBBES also reported the scientific proceedings had in the Section of Natural History, during yesterday and to-day, as follows:Theory of the Geological Action of the Tides, by Lieut. C. H. DAVIS, U. S. Coast Survey.

On the Local Distribution of Marine Animals, by M. DESOR.
On the Fishes of Lake Superior, by Prof. AGASSIZ.

On the Foraminifera, derived from deep sea soundings, in the Coast Survey, by Prof. J. W. BAILEY.

On the Tracks of Mollusca, as an evidence of Beaches in the Silurian period.

On the Geographical Distribution of Coleoptera, by Dr. J. L. LE

CONTE.

The reports made by the Secretaries of the Sections were severally adopted.

A communication from the officers of the University at Cambridge was received, inviting the Association to hold its next annual session in that city. Action upon the adoption of the proposal was postponed, and the invitation was referred to the Standing Committee.

A motion was made, that the proceedings be published in the form of a Journal, which proposition, after a discussion, participated in by Messrs. S. W. ROBERTS, Dr. M. W. DICKESON, Prof. W. R. JOHNSON, Prof. L. AGASSIZ and others, was finally referred to the Standing Committee.

The Chairman of the Standing Committee nominated for membership in the Association Dr. J. B. LINDSLEY, of Nashville, Tenn., and the vote being taken, the nomination was confirmed.

A communication was received from the Philadelphia Athenæum, inviting the members of the Association to visit the rooms of their Institution during the session, which was, on motion, accepted.

On motion, adjourned, to meet again at half-past 4 o'clock, this af

ternoon.

Friday, September 22, 4 o'clock.

The Association met pursuant to adjournment, WILLIAM C. REDFIELD, Esq., President, in the chair.

The Chairman of the Standing Committee reported a resolution accepting the invitation of the officers of the University at Cambridge to hold the next Annual Meeting of the Association in that city, and recommending that the 14th of August, 1849, be the day set apart for such assembling. After a short discussion, and an explanation of the reasons for adopting that as the period of meeting, the resolution was adopted.

Lieut. MAURY, of the U. S. Navy, then presented a communication ON THE WINDS AND CURRENTS OF THE OCEAN, of which the following is an abstract:

Lieut. MAURY reminded the Association of its having appointed a committee, in 1844, to represent to the Secretary of the Navy the importance of the information which our public cruisers might collect with regard to the Gulf Stream, and other subjects of general in

terest.

It was scarcely necessary to say, that the Secretary who had signalized his administration of the Navy by the most enlightened and liberal policy, with regard to the true interests of science, and of which the National Observatory and Dead Sea Expedition were monuments, gave to the representations of the committee the most respectful consideration.

It was owing to an impulse which was thus given, that Lieutenent MAURY had been enabled to carry into effect a favourite idea, long entertained, of constructing a series of charts, which should give to each navigator, who would consult them, the benefit of the experience of all who had gone before him, as to the winds and currents, and the like, in any given part of the ocean.

Charts of the North Atlantic, upon this plan, were exhibited before the Association. They are so constructed as to show at a glance the prevailing winds, currents, temperature of the water, &c., for every month in all parts of the ocean. The characters or symbols for the winds are so contrived, that they show, at once, both the direction and strength of the wind.

To obtain the results thus exhibited, involved immense labour: