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a piece of metal. The sound became dull and dead, but reacquired its peculiar sharpness in proportion as the effervescence ceased. This experiment may be familiarly performed on a glass of sodawater, or champagne; and it will be immediately observed, that the alteration in the sound is great in proportion to the violence of the effervescence. If the effervescence has ceased, upon restoring this by dissolving in the liquid a quantity of powdered sugar, the phenomenon will be again remarked as strikingly as before.

The explanation afforded by Dr. BREWSTER, in his interesting work on Natural Magic, appears perfectly satisfactory. "Sound," he observes, "moves with different velocities, through media of different densities; hence the wave which produces the sound will be partly reflected in passing from one medium to another, and the direction of the transmitted wave changed. Thus, in passing through such media, different portions of the wave will reach the ear at different times, and thereby destroy the sharpness and distinctness of the sound." In the instance above cited, we have the sound transmitted partly by the stratum of carbonic acid covering the surface of the liquid, and partly by the surrounding air; and, on account of the difference of density in the two media, we have so great an interruption to the uniformity and regularity of the vibrations, that the sound becomes changed in the manner already described.

During the last winter, I had occasion to apply the knowledge of this principle to a use which it may not be uninteresting to notice. Some jars, containing carbonic acid gas, prepared for a lecture, had by accident become intermixed with other jars standing on the table, and containing other gases. Some doubts arose as to which of these vessels contained carbonic acid; but the question was speedily determined by gently tapping the exterior of the jars with an iron nail, the sound emitted by the vessels containing the carbonic acid forming a most striking contrast with that given out by the others. The knowledge of this fact may not be without its use to those who are engaged in experiments on the gases.

On the Preparation of Carbonic Oxide Gas.

By A. S. TAYLOR, Esq.

THIS gas appears to have been first obtained by its discoverer, Dr. PRIESTLEY, in the distillation of charcoal with oxide of zinc; and the process for its preparation seems to have undergone but very little alteration since his time. In our most popular works on Chemistry, at least in those of HENRY and BRANDE, the directions for its preparation are extremely complex, and are unfitted for its extemporaneous production; as, for example, during a lecture. A strongly heated furnace, an earthen or iron retort, &c., with a gasometer, are, according to the processes given by these chemists, indispensably necessary to the experimentalist; whereas, in the

process given below, the gas may be readily produced in a few seconds, and on the table of the laboratory or lecture-room.

A small retort is to be filled to about one third with crystals of oxalic acid. A quantity of strong sulphuric acid is then to be added, but not more than is sufficient to moisten the crystals. The heat of a spirit-lamp may now be applied, and the gas will come over abundantly, and may be collected in the ordinary way over a water-bath.

The decomposition which here takes place will be readily understood. Oxalic acid consists of carbon and oxygen, in the proportions intermediate between those of carbonic acid and carbonic oxide. The crystals contain about one half of their weight of water, and the sulphuric acid acts by taking this water, and liberating the carbon and oxygen, under the form of the two compounds mentioned.

The gas obtained in this way is, therefore, always combined with carbonic acid; but the same fact is invariably observed with regard to the gas obtained by distilling an earthy carbonate with iron filings. To procure the carbonic oxide perfectly pure, it will be necessary, in either case, to allow it to pass over a cream of lime, or through a solution of caustic potash.

In a work recently published by DUMAS, I find the binoxalate of potash recommended; the salt being treated with sulphuric acid, and heated in a retort. I am not aware that this possesses any advantages over the method which is above described, and which I have been for a long time in the habit of employing; but either the one or the other must be regarded as much more commodious, and less troublesome to the experimentalist, than the processes ordinarily recommended in works upon the science.

INTELLIGENCE.

KING'S COLLEGE, LONDON.

On Saturday last, the 25th ultimo, the prizes awarded to the successful candidates in the several classes of the medical department were distributed, at a public meeting held in the large theatre, in the College. The Bishop of London presided on the occasion.

The following is a list of the students to whom prizes and certificates of honour were adjudged.

First gold medal, for general medical proficiency Mr. T. E. Rawson.
Second ditto

ANATOMY

E. J. Chance.

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ANATOMICAL DEMONSTRATIONS-Silver medal......Mr. John Soden.

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Mr. LEATHE'S prizes for regularity of conduct, Mr. Leacock. and attention to religious duties

S

Atkinson.

MONTHLY LIST OF MEDICAL BOOKS.

[Medical Works cannot be entered on this List unless a copy be sent for the purpose, the titles of Books having frequently been sent to us as published, which have not appeared for weeks, or even months, after.]

Part XIX. The Principles and Practice of Obstetric Medicine, in a Series of Systematic Dissertations on Midwifery and on the Diseases of Women and Children. Illustrated by numerous Plates. By D. D. DAVIS, M.D., M.R.S.L., &c.-4to. John Taylor, London.

An Address to the Governors of the Birmingham General Hospital, on the Propriety of appointing Assistant Surgeons to that Institution. By RICHARD MIDDLEMORE, Member of the Royal College of Surgeons, &c.-Birmingham.

A Manual of Pharmacy. By WM. THOMAS BRANDE, F.R.S. &c. Third Edition, corrected and enlarged.-8vo. pp. 544. Renshaw and Rush, London.

Translated from the French,

The Analysis of Inorganic Bodies. By J. J. BERZELIUS. by G. O. REES.-12mo. pp. 164. Longman and Co., London. Observations on the Testicles. By JAMES RUSSELL, F.R.C.S., late Regius Professor of Clinical Surgery in the University of Edinburgh, &c.-8vo. pp. 276. Longman and Co.

No. II. Hortus Medicus; or, Figures and Descriptions of the more important Plants used in Medicine, or possessed of Poisonous Qualities; with their Medical Properties, Chemical Analysis, &c. By GEORGE GRAVES, F.L.S. &c. and JOHN DAVIE MORRIES, M.D. &C. --4to. Longman and Co. London.

This elegant and useful work deserves the support of the profession, and all lovers of botanical knowledge. The engravings are particularly well executed, and the descriptive text is concise and accurate.

An Inquiry into the Causes of Respiration, of the Motion of the Blood, Animal Heat, Absorption, and Muscular Motion; with Practical Inferences. By JAMES CARSON, M.D., Liverpool. Second Edition.-8vo. pp. 447. Longman and Co., London.

Considérations Pratiques sur les Névralgies de la Face. Par -HALLIDAY, Docteur en Médecine des Facultés d'Edinbourg et de Paris.-8vo. pp. 175. A. Pinard, Paris.

528

APOTHECARIES' HALL.

NAMES OF GENTLEMEN to each of whom the Court of Examiners have granted Certificates:

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METEOROLOGICAL REGISTER,

By Messrs. HARRIS and Co., Mathematical Instrument Makers, 50, High Holborn.

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