A Paper on the Generation of Fishes, by Dr. J. L. Prevost, was read.

The principal object of this paper was to describe the devolopement of the foetus of the bull's-head, or miller's-thumb (cotus gobio).

The testicles are composed of a congeries of small canals, terminated at the upper part by cœca, and containing the semen, which they discharge into a common canal opening into the meatus, by which the urine is discharged. Under the microscope the semen appears composed of globules and animalcules. The eggs of the female are emitted covered with mucus, which swells up when it absorbs water. The yolk is enveloped in a fine membrane, adhering to which is a white granulated cicatricula, not visible before fœcundation.

The description of the developement of the foetus given by the author is not intelligible without the annexed plate.

The Society then adjourned over one Thursday, to meet again on

Thursday, June 17;

at which meeting Lovell Edgeworth, Esq., was admitted a Fellow, and the following papers were read:

On the Action of finely-divided Platinum on Gaseous Mixtures, and its application to their Analysis. By W. Henry, M.D., F.R.S. In the first section of this paper the author described the action of finely-divided platinum, at common temperatures, on mixtures of hydrogen and olefiant gas with oxygen; of hydrogen and carburetted hydrogen with oxygen; of hydrogen and carbonic oxide with oxygen; of hydrogen and cyanogen with oxygen; of carbonic oxide and carburetted hydrogen with oxygen; of hydrogen, carburetted hydrogen, and carbonic oxide with oxygen; and of the same with the addition of olefiant gas. From the experiments detailed under these several heads, it appears that when the compound combustible gases mixed with each other, with hydrogen, and with oxygen are exposed to platinum balls or sponge, the several gases are not acted upon with equal facility, but that, next

to hydrogen, carbonic oxide is most disposed to unite with oxygen; then olefiant gas, and lastly carburetted hydrogen. By due regulation of the proportion of hydrogen, the author remarks that it is possible to change the whole of the carbonic oxide into carbonic acid, without acting on the olefiant gas or carburetted hydrogen; he observes, however, that, with respect to olefiant gas, this exclusion is attended with some difficulty, and it is generally more or less converted into carbonic acid and water.

The second section of this paper related to the action of finelydivided platinum upon gaseous mixtures at increased temperatures. In these experiments the gases mixed with oxygen enough to saturate them, were severally exposed in small retorts containing a platinum sponge, and immersed in a mercurial bath to a temperature which was gradually raised till the gases began to act on each other. It was thus found that carbonic oxide began to be converted into carbonic acid at about 300°; olefiant gas was decomposed at about 500°; carburetted hydrogen at a little above 555°; and cyanogen appeared to require a red heat.

Muriatic acid mixed with half its volume of oxygen began to be acted upon at 250°; and ammoniacal gas, with an equal volume of oxygen, at 380°.

Adverting to the property inherent in certain gases of retarding the action of the platinum when they are added to explosive mixtures of oxygen and hydrogen, Dr. Henry observed that it is most remarkable in those which possess the strongest attraction for oxygen, and that it is probably to the degree of this attraction, rather than any agency arising out of their relations to caloric, that we are to ascribe the various powers which the gases manifest in this respect.

Dr. Henry concluded this communication by pointing out the best methods of analyzing mixtures of the combustible gases in unknown proportions.

An Account of the Organs of Generation of the Mexican Proteus in a developed state. By Sir E. Home, Bart., V.P.R.S.

1

The specimens described in this paper were taken in the month

of June, in a lake three miles from Mexico, at an elevation of 8,000 feet above the level of the sea; the usual temperature of the lake is 60°, and they are in such abundance as to form a principal article of food of the peasantry.

By the assistance of a series of annexed drawings by Mr. Bauer, Sir Everard fully describes the male and female organs of these animals, and is enabled to decide that they are a full grown and perfect tribe. "The attack therefore," says the author, "made upon Mr. John Hunter's sagacity, by M. Rusconi, in his work Sur les amours des Salamandres aquatiques, retorts upon himself."

On the Effects of Temperature on the Intensity of Magnetic Forces, and on the Diurnal Variation of the Terrestrial Magnetic Intensity. By S. H. Christie, Esq. M. A.

The details of the author's experiments upon the above subjects are given in an extended series of tables. Commencing with a temperature -3° F. up to 127°, Mr. Christie found, that as the temperature of the magnets increased, their intensity diminished, in direct contradiction to the notion of destroying magnetism by intense cold. From a temperature of 80° the intensity decreased rapidly as the temperature increased, and at above 100°, a portion of the power of the magnet was permanently destroyed.

Additional Experiments and Observations on the Application of Electrical Combinations to the Preservation of the Copper Sheathing of Ships, and to other Purposes. By Sir H. Davy, Bart. P.R.S Since his former communication, the President has had an opportunity of pursuing his researches upon the above subjects, upon an extended scale, and with results perfectly conclusive and satisfactory. He found that sheets of copper defended by from 3 to 2 part of zinc or iron, exposed for many weeks to the full flow of the tide in Portsmouth harbour, suffered no corrosion, and that even Too part of cast iron exerted great protecting influence.

Boats, and the sides of ships, protected in this way, were also similarly preserved.

Of the different protecting metals, cast iron is most convenient, and the plumbaginous substance formed upon it does not impede its electrical action. The President formerly anticipated the deposition of earthy substances upon the negative copper, and this he now found to take place upon sheets of copper exposed about four months to sea water, and defended by from to their surface of zinc and iron; they became coated with carbonate of lime and magnesia; but this effect is easily prevented, by duly diminishing the proportion of the protecting metal, so as to prevent the excess of negative power in the copper which then remains bright and clean.

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The author observed that many singular facts had occurred in the course of his researches, some of which bore upon general science. Weak solutions of salt act strongly upon copper, but strong ones do not affect it, apparently because they contain little air, the oxygen of which seems necessary to give the electro-positive power to these menstrua. Upon the same principle, alkaline solutions and lime-water prevent the action of sea-water on copper, having in themselves the positive electrical energy which renders the copper negative.

The President concluded this paper with some further applications of electro-chemical theory to the subject of it, and referred to the principles developed, as suggesting means of preserving instruments of brass and of steel, by iron and by zinc, a circumstance already taken advantage of by Mr. Pepys, in enclosing delicate cutting instruments in handles or cases lined with zinc.

The Society then adjourned for the long vacation.

ART. XI. Proceedings of the Royal Institution, 1824.

THE Lectures were commenced in the Amphitheatre of this Institution on Saturday, the 7th of February, when an introductory discourse was delivered by Mr. Brande.

The following arrangements in respect to the Lectures were announced to the Members and Subscribers.

On Electricity, Electro-Chemistry, and Electro-Magnetism. By William Thomas Brande, Esq., F.R.S. London and Edinburgh, Professor of Chemistry to the Royal Institution. This Course of Lectures will comprise an experimental Illustration of the Elementary doctrines of Electricity bearing upon its applications to Chemical Science and to the Theory and Phenomena of Magnetism. To commence on Saturday the 7th of February, at Two o'clock, and to be regularly continued on each succceding Saturday, at the same hour, till further notice.

On the leading Subjects of Mechanical Philosophy, and their recent Improvements, particularly Optics and Hydraulics. By John Millington, Esq., F.L.S., Sec. Astron. Society, &c., Professor of Mechanics to the Royal Institution. To commence on Thursday the 12th of February, at Two o'Clock, and to be regularly continued on each succeeding Thursday, at the same hour, till further notice.

On Botany, with the Principles of Vegetable Physiology. By John Frost, Esq., Professor of Botany to the Medico-Botanical Society of London. To commence after Easter.

On Plane Geometry. By John Walker, Esq., formerly Fellow of Trinity College, Dublin, and M.R.I.A. To commence after Easter. On Music. By W. Crotch, Mus. D., Professor of Music in the University of Oxford. To commence after Easter.

On Zoology, comprehending a Survey of the Class Mammalia. By J. Harwood, M.D., F.L.S.

On European Literature. By the Marquis Spincto.

On the Objects of Vegetable Chemistry, and the applications of