if not quite as large as the Moon, though in other respects bearing no resemblance to that body, being of a hazy contour, emitting a dazzling blue light at first, which became afterwards of a yellowish tint. Although visible for only a few seconds, no person in the open air at the time could fail to notice it as it came out of the sky with the quickness of a flash of lightning, and disappeared equally suddenly, its course being in the direction from Mars to the Moon. We hope in our next to be able to give some account of its track and height.

The Comptes Rendus, November 17, contain a letter from P. Secchi to M. Elie de Beaumont, concerning the planet Mars, in which the former states, that there can be no doubt that the white polar blotches on that planet are masses of snow, or of clouds condensed at the poles; that the persistence of the blue channels show them to be seas, and the red patches continents.

The comet first discovered by M. Bruhns will be visible in those latitudes during the month of January. On January 1, 1863, it will be close to the star Kappa Coronæ (of 4 mag.), and not far distant from the star Zeta (of 4th mag.). It travels after this to the constellation of Vulpecula, and is close to Flamsteed 25 on January 28 (of 6th mag.). It is at its greatest brilliancy on January 1.

The second comet has disappeared at present, but may probably be visible at the end of February. It likewise is at its greatest brilliancy on January 1. On February 17, it is in the constellation of Cetus.

BOTANY.

Artificial Formation of Cork.-M. Casimir de Candolle, the third of that name, describes the mode by which, in Algeria, superior cork is obtained from the cork oak. The rough corky layer is removed down to the subjacent cellular envelope, or green layer, during summer and autumn. In consequence of this removal a new corky stratum forms upon the green layer at a variable distance from its denuded surface. This stratum grows in annual layers upon its internal surface, just as the original worthless corky layer did; but it is much finer, and more elastic. After seven or eight years it is sufficiently grown to be removed, and the same process is repeated. This may be done many times, and new cork removed every seven years to an almost indefinite extent.

The Exhalation of Ozone by Plants.-In the Comptes Rendus, M. Kosman details experiments from which he deduces these results: That plants disengage ozonised oxygen from their green parts, during the day, in greater ponderable quantity than exists in air. During the night the same thing takes place, if accumulated masses of vegetation are in vigorous growth. Town plants disengage less ozone during the day than country plants; hence the air of the country is more vivifiant. In the midst of the town there is more ozone in the air at night than during the day. The corollas, or coloured parts of the flower, do not disengage ozonised oxygen; and, lastly, in inhabited rooms, oxygen does not generally exist in an ozonised

state.

Hybrid Plants returning to their Original Species.-M. Naudin, having fertilized plants of Datura stramonium with others of D. Tatula, afterwards sowed the seeds produced by this union, and obtained hybrids of the first generation. These hybrids were isolated; and a few seeds coming to maturity, they were sown in April, 1862, and produced twenty-two plants of the second generation, viz., five of Datura stramonium in all its purity, whose fruits ripened and came to maturity; and nine typical plants of Datura tatula. The remainder were more or less of a hybrid character. M. Naudin believes that this third generation of the hybrids will turn completely to D. tatula. These remarkable facts, which demonstrate the fact of the spontaneous disappearance of fertile hybrids, without the intervention of a crossing with one or other of the parent species, appear to M. Naudin at present inexplicable.

Acclimatisation of Japanese Plants.-M. Simon, writing from Japan, continues to recommend valuable plants for introduction into the Jardin d'Acclimatisation. The hemp palm (Chamaerops excelsa) bears a temperature of 10° Fahrenheit, requiring no particular care. The stalk of each leaf is covered with filaments of various fineness, of which the coarsest are used for ropes, and the finer for nets. Another plant he speaks of is the soja, a kind of bean used by the Japanese for a condiment, and a very savoury adjunct to almost every Japanese dish.

The Sago Palm.-Mr. Wallace, who has returned, laden with valuable information, from his Eastern travels, speaks of the sago palm as the staff of life to the inhabitants of New Guinea and the adjacent islands. He described it as a truly extraordinary sight to behold a whole tree trunk converted into human food, with as little labour as is required to convert corn into bread. A single good tree will produce six hundred pounds of sago cakes; and with an expenditure of ten days' labour, a man may produce food sufficient for a year's consumption. The natural result is improvidence, laziness, degradation, and misery.

Botany of North Yorkshire.-Local floras and local faunas being of great value and importance, we gladly notice the preparation of a work to include the flora of this interesting part of England. North Yorkshire stands midway between the North and South of Britain, and can claim for its own about three in four British species. About 1,600 species of flowering plants, ferns, and mosses will be described; and as a valuable adjunct, sets of the rare and critical plants of the district are prepared, containing each about one hundred specimens.

The Cotton Substitute.-The substance proposed by Mr. Harben, and spoken of in our last as favourably mentioned as a substitute for cotton, has now long been known to be the fibre obtained from the Grass Wrack (Zostera marina). The subject has since that time been before the public, and well canvassed by practical men. The result, at present, appears to be that, although it may prove useful as a supplement to cotton, or for mixing with other fabrics, neither the nature of the fibre, nor the source of its supply, renders it probable that it can make us independent of the cotton-plant.

The Potato Disease.-Dr. de Bary, of Freibourg, has recently published a pamphlet containing an epitome of all that is known regarding the potato disease, and gives the results of his observations. He finds the theory of its being due to a parasitical growth to be correct. A seed or spore of the parasite, when placed in the leaf, he says, will penetrate the tissue in twelve hours, and in sixteen hours it bursts through the leaf, and is ready to reproduce itself at the rate of 19,620 zoospores for every square line of its surface.

CHEMISTRY.

URE CHEMISTRY.-Among the various matters of scientific interest,

purity of ice. It appears that water is rendered almost as pure by congelation as by distillation; the calcareous and magnesian salts being forced out, in the act of freezing, as completely as the more soluble salts. He states that frozen water may be used for most chemical purposes in place of distilled water. Dr. Rüdorff has found that when a saline solution has frozen to such an extent that there is not sufficient water remaining to hold the salt in solution, it crystallizes.

A new method of preparing hyposulphuric acid has been described by Gelis; it consists in acting on sulphurous acid with hydrated peroxide of iron; the peroxide is suspended in water and sulphurous acid-gas passed into the solution where a compound of sulphurous acid and peroxide of iron is formed, which decomposes in a short time into hyposulphate and sulphite of protoxide of iron.

Mendius has found that when the nitrites are exposed to nascent hydrogen, a transformation takes place, and an amine base of the next higher homologous alcohol formed; the method of proceeding was to act on a mixture of the nitrite with sulphuric acid by metallic zincs; by this method hydrocyanic acid, acetonitrile, butyolonitrile, and benzonitrile, were transformed into methylamine, ethylamine, amylamine, and a new base of the composition, C,H,N.

The conversion of aldehyd into alcohol by means of nascent hydrogen has been accomplished by Wurtz. To effect the change, all that is necessary is to expose a dilute solution of aldehyd in water to the action of an amalgam of sodium, when part of the aldehyd becomes resinified and the other part combines with hydrogen, to form a body possessing all the properties of ordinary alcohol.

This process of transformation of organic bodies by the introduction of nascent hydrogen seems to be of general application, for Linneman has changed sugar into mannite, by acting with sodium amalgam on cane sugar, which has been changed to grape sugar by sulphuric acid; and benzoic and valerianic aldehyds have been converted by Friedel into benzoic and valerianic alcohols.

Mr. J. J. André has lately studied the action of chromic acid on vegetable alkaloids. He has found that definite crystallizable compounds

can be prepared, but that great care is requisite to prevent a reduction of the chromic acid taking place; quinine and brucine combine in two proportions with chromic acid, but cinchonine, quinidine, and strychnine form only one compound, for on adding a solution of neutral chromate of potash to a solution of a salt of one of these bases, a portion of the base was precipitated from the solution, and the neutral chromate of the base was found in the filtrate.

The formation of organic compounds by synthesis is highly interesting, inasmuch as it is a great onward step to the investigation of the processes by which these bodies are naturally formed. The number of such transformations is rapidly increasing, and no doubt eventually some light will be thrown on the changes that occur during the growth of animals and vegetables, and the formation of the complex and varied organic bodies found in their different parts. The formation of acetylene by the passage of an electric spark between two charcoal points, placed in an atmosphere of hydrogen, is of great interest, inasmuch as it is formed by the synthesis of its elements without the pre-existence of an organic body; and starting from this substance a whole series of organic bodies may be formed by further synthesis, as has been shown by Berthelot, who made the discovery of the synthesis of acetylene.

An interesting communication by Mr. E. Dancer has been read before the Chemical Society, "On Hypobromous Acid," in which the author has demonstrated, by most conclusive experiments, the chemical properties of this body. He did not succeed in preparing hypobromous anhydride, but found that the hydrated acid could be produced by the action of bromine water upon the red oxide of mercury, similarly to hypochlorous acid, to which it had a great analogy, possessing also powerful bleaching properties. This body was also formed by the action of bromine upon nitrate of silver, as had been previously shown by Mr. Spiller. It was impossible to prepare a more concentrated solution than that containing six per cent.: partial decomposition ensued on distillation at ordinary pressures, but by the aid of the air-pump this could be prevented. With dilute solutions of the caustic alkalies, bromine gave rise to the production of bleaching solutions, containing soluble hypobromites, but with concentrated solutions bromates and bromides were formed..

The General Medical Council, after some deliberation, have resolved to leave the grain weight unaltered, and to retain the avoirdupois pound and ounce, but to discontinue the use of the drachm and scruple in the Pharmacopoeia. The confusion occasioned by the introduction of new weights, and the difficulty of adapting old formula to a new system, are objections to a change in the standard weights; but considering the numbers of different systems of weights and measures now existing, the introduction of a decimal notation would afford an immense simplification, and possibly prevent many mistakes.

Dr. Sheridan Muspratt has recently made analyses of the waters of the mineral springs of Scarborough, from which it would appear that there has been some mistake as to the comparative medicinal properties of the north and south springs, the north spring being richer in magnesian salts, but containing less iron than the south.

The results of the analysis are expressed in the following tables :

A process for the preparation of silicated hydrogen in considerable quantities has lately been brought into notice. Dr. Martius has been engaged in making metallic magnesium by reduction of the chloride with sodium; for this purpose he employed an earthen crucible, and on examining the product he found that it contained silicium, and gave off inflammable gas during solution in hydrochloric acid. By introducing larger quantities of silicium he was able to prepare the gas in a state of greater purity; it possesses, like phosphoretted hydrogen, the singular property of spontaneous inflammability.

It is generally stated, in books on chemistry, that camphor has a tendency to deposit towards the light, by which it is meant, that if a bottle containing camphor be exposed to sunlight, the camphor will be deposited in crystals on that part of the bottle which is turned towards the light. Mr. C. Tomlinson's experiments however have led him to the conclusion that heat, not light, is the cause of the phenomena observed. He exposed a great number of bottles of camphor to light under different circumstances (for instance, when immersed in water), and found that no deposit was formed under those conditions that prevented a radiation of heat.

II. APPLIED CHEMISTRY.-A patent has been recently taken out by Mr. James Webster, for a process for making oxygen gas from nitrate of soda, and at the same time obtaining certain other valuable products. The process consists in heating a mixture of the nitrate with oxide of zinc in retorts; the nitric acid is decomposed by the heat into oxygen and nitrogen, the soda remaining behind, is separated by water from the oxide of zinc. It is proposed to employ the oxygen in metallurgical operations, and for