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With a telescope of three-fourths the original size nothing was visible. The second variable nebula is situate at 3h. 38m. of R.A., and +23° 23′ of Decl. In 1859, October 19, Tempel describes it as large and bright, with a twofoot telescope. In December, 1860, it was scarcely visible in a six-foot telescope; whilst, at the present time, it is scarcely visible in the largest instruments. It is to Professor D'Arrest that we are indebted for these startling discoveries, which completely alter all our notions in respect to nebulæ. It is very remarkable that the two new variable nebula are situate within nine and eight degrees from the missing nebulae of last February. The idea of a cosmical cloud, which has been imagined in order to explain other phenomena, will doubtless be reverted to in the present instance. There are very few nebule in this region of the heavens, although many clusters and knots of stars. Among others, we have a double nebula, R.A. 3h. 11m., + 40° 43'; a nebula, R.A. 3h. 20m., Dec. +36° 45'; a nebulous star, R.A. 3h. 59m., Dec. + 30° 20′; and a single nebula at R.A. 4h. 19m., Dec. + 34° 54'.

Mars, September 17, 1862, at 11 p.. by J. Buckingham, Esq., F.R.A.S.

It will be some years before Mars is seen to such perfection as at the present time. As it will be the only telescopic object among the planets for the next few months, it will of course be duly looked after. It will be the most brilliant object in the heavens during the months of October, November, and December, and will be visible even for the first three or four months of the year 1863. We give a drawing of its appearance on September 17.

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A striking instance of the unnoticed changes which are constantly going on in the heavens is the case of the star in Ophiuchus, marked (b) in catalogues and maps. Although the variations in brilliancy of this object have been very decided, yet it has not been until the last few months that they have been remarked, and duly inquired into. It has been found that this star fluctuates through all grades of brightness between the 6th and 3 magnitude. It was reckoned of the former lustre in July, 1849, by Argelander, whilst in June, 1862, it had increased to the latter. The name of Argelander is a sufficient guarantee for the correctness of the first observation, whilst that of the latter can be verified at the present time. Doubtless, the future changes in the brilliancy of this object will be a matter of considerable moment. One has only to compare the faintest of the seven stars in the "Plough" with that which is merely visible to the naked eye, to realize the difference between the two objects.

With the great Foucault reflector of the Paris Observatory, M. Chacornac has been able to resolve the annular nebula of Lyra into separate and distinct stars. He describes the appearance of this well-known object as if looking down a funnel. He verifies the measurement of Sirius and its companion as previously given by him.

The present summer has been fruitful in solar spots of considerable size. In the gallery of "philosophical instruments," at the Exhibition, we notice the photographs of Mr. Titterton, of Ely, bearing upon this subject, and more particularly that of August 4 of the present year, where the spot, lying at the margin of the sun, makes a considerable indentation on that part. Another remarkable spot was seen by Mr. Hodgson, on June 8. The Saturnian phenomena, observed during the absence of the ring, have been sufficiently curious. Mr. Dawes has made many remarkable observations of Saturn and its satellites and ring, but more particularly an immersion of Titan in the shadow of Saturn, on May 25, and a transit of the shadow of Titan across the disc of Saturn on June 2.

BOTANY.

Araucaria Imbricata.-The destruction of two fine specimens of the Chili pine in the Edinburgh Botanic Garden by the frost of December, 1860, has given Professor Balfour the opportunity of making some observations upon the bark of these trees. Removing the leaves and outer bark, quadrilateral markings appear, varying in form according to their height up the stem, each of them having been connected with a leaf, and more distinctly visible when the external bark separated spontaneously. The appearances thus presented show so close a resemblance to the marks upon the fossil stems, called Sigillariæ and Lepidodendron, usually looked upon as allied to ferns and lycopods, that Professor Balfour thinks the subject has been too hastily decided, and that it should at least be re-considered; very properly insisting, that the fossil botanist who decides upon mutilated ancient plants should at least have a good knowledge of those now covering the globe.

Substitute for Paper.-M. Eugène Simon has recently sent from Japan to the Société d'Acclimatation some young trees the bark of which is used by the Japanese for making paper. These belong to the mulberry subdivision of the bread-fruit tribe, and are closely allied to the tree from which the Chinese manufacture what is termed crape paper, and termed Broussonetia papyrifera. The Japanese trees are B. kaminoki, of Van Sieboldt; and this bark, when properly prepared, could be imported for half the price of rags into this country. Moreover, it might easily be acclimatised in various parts of Europe, upon stony, calcareous soils. The branches are cut off every two years, placed for half an hour in hot water, which causes the bark to separate; it is then dried, macerated, and bleached several times, and finally boiled in a lye of ashes; then dried, and pounded into a pulp with water, and the pulp made into sheets.

Substitute for Cotton.-Another important article of consumption which has much failed of late has taxed the ingenuity of inventors to find a

substitute. The cotton-world is on the tip-toe of expectation from the report that a substitute for cotton has been discovered, which has been submitted to the examination of experienced hands, and pronounced, for colour, length, and fineness, all that can be desired. At present, the material which is thus characterized is not divulged, but the inventor or discoverer asserts that it is capable of being produced in any quantity, and at small expense; that is, as low, or lower, than the average price of American cotton.

Lathyrus Tuberosus.—This vetch, common in France, where it is called the Lorraine truffle, and which might easily be cultivated in England, is stated, in the "Phytologist," to possess a tuber with a milky saccharine taste, and a whitish fecula, more palatable than the potato, and infinitely more valuable than the batatas, or sweet potato. The flower is handsome, large, red, and pea-shaped; and it is recommended as worthy of acclimatization in this country.

Botanical Expedition to British Columbia.-The committee of the Oregon Botanical Expedition have resolved to send Mr. Robert Brown to Vancouver's Island, on a scientific mission, with directions to explore British Columbia, and the countries adjacent to the Rocky Mountains, and to transmit seeds and roots of plants to the Oregon Association in London.

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CHEMISTRY.

URE CHEMISTRY.-That chemical "will-o'-th'-wisp," ozone, has been further investigated by the indefatigable experimenter, Schönbein. He prepares ozone by dissolving pure manganate of potash in oil of vitriol, and introducing into the green solution pure peroxide of barium, when ozone, mixed with common oxygen, makes its appearance, and may be easily detected by the smell and other tests. Amongst other curious and important facts which the Professor has discovered in these researches is one connected with the generation of nitrite of ammonia. This salt, he finds, is always produced when water evaporates in contact with the atmosphere: the mere passage of the water from the liquid to the gaseous state ozonizing some of the atmospheric oxygen, which in its turn converts some of the nitrogen and aqueous vapour into nitrite of ammonia. This may be shown in a variety of ways for instance, when a piece of clean linen is moistened with distilled water and allowed to dry in the open air, it will be found to contain nitrite of ammonia. This fact is of great interest in connection with the chemistry of vegetation. It has long been debated where and how plants obtain their nitrogen-whether from the soil or from the atmosphere. Schönbein shows that every pore over the whole surface of a plant, by continually evaporating water into the atmosphere, becomes a generator of nitrite of ammonia-preparing part, if not all, of its nitrogenous food; the same thing likewise happening in the ground on which it stands. Schönbein, therefore, inclines to Liebig's opinion-that no plant wants any artificial supply of ammonia, there being enough offered by natural means.

A curious compound of manganese with oxygen-permanganic acid— has been investigated by Terreil. The most remarkable fact connected with this body is its volatility. He prepares this acid by distilling, at a moderately low temperature, a solution of permanganate of potash in pure sulphuric acid. Violet vapours are evolved, which condense to a thick liquid of a greenish-black colour and metallic appearance. It is perhaps the most energetic oxidizing agent known: it instantly sets fire to paper and alcohol, the latter with explosion; and, when placed in contact with a fatty body, it detonates suddenly, with emission of a beautiful white light. A very beautiful effect is produced when a few drops of a solution of sulphite of potash are poured upon permanganic acid : a vivid disengagement of light is produced, and a large quantity of acid is carried off in the form of violet vapours, which are reduced in the air and fall down in the shape of brown flocks.

Wanklyn and Carius have prepared a compound of hydrogen and iron. By allowing iodide of iron to react on zinc-ethyl, several gases are evolved, and a residue of hydride of iron is left in the tube: it is a black powder resembling metallic iron, and gives off pure hydrogen when gently heated. When dry, it may be kept unchanged; but if moistened with water, it gives off hydrogen and becomes converted into oxide of iron. Hydrochloric acid decomposes it in a similar manner, forming chloride of iron-hydrogen being evolved at once from the acid and the hydride.

Further information on Thallium, the new metal, whose existence was first detected by spectrum analysis, has been published by the discoverer, Crookes. It is a heavy metal, bearing a remarkable resemblance to lead in its physical properties. Its specific gravity is about twelve. It has a brilliant metallic lustre, but tarnishes very readily. It is very soft, and may be easily cut with a knife or scratched with the nail; it may also be hammered out and drawn into wire; it fuses below redness, and several pieces may with care be melted together and cast into one lump. The metal is not sensibly volatile below a red heat; its atomic weight is very high. Thallium is readily soluble in nitric acid, and forms well-defined crystalline compounds with oxygen, chlorine, and various acids. The most characteristic property of the new element is, however, the magnificent green colour which it communicates to a flame: this light is perfectly homogeneous and gives a spectrum consisting of only one green line. Thallium, therefore, produces the simplest spectrum of any known element. The line appears to be identical in refrangibility with a welldefined line in the barium spectrum. Guided by this delicate test, the discoverer has found that thallium is by no means a sparingly-diffused metal-several pyrites from different parts of the world contain it; and in a paper which the author read before the Royal Society last session he pointed out several sources and localities from which thallium might be obtained by the hundredweight at a time.

Morren has examined the phenomena of phosphorescence when the induction spark is passed through rarefied gases. No simple or compound gas singly presents the phenomenon of phosphorescence; but when a mixture of sulphurous acid and atmospheric air is placed in a tube, and the induction spark passed through the rarefied mixture, a splendid and per

manent phosphorescence is produced. The cause of this is now shown to be the successive decomposition and recomposition of a singular body well known to chemists, the compound which anhydrous sulphuric acid forms with nitrous acid. When in the state of vapour, and very rarefied, the spark separates it into its two constituents, nitrous acid and sulphuric acid, which have only feeble affinities for each other. When the electricity ceases to pass, the elements cannot coexist in the vapourous state without recombining, especially in the presence of oxygen; and it is during these molecular evolutions that the phosphorescence is kept up.

The action of the voltaic pile upon different substances in the state of igneous fusion has been examined by M. Giradin, in the laboratory of the Duc de Luynes. Passing over the results obtained with salts of potash and soda, which are of no special interest, we may mention the conclusions at which he has arrived in the case of alloys. All alloys, without exception, lose their homogeneousness when traversed by the current. Thus, fused plumbers' solder, when electrolized, becomes brittle at the positive pole, and soft and malleable towards the negative pole. The amalgams and alloys of potassium and sodium can be operated upon when cold. The amalgam of sodium decomposes water when taken at the negative pole, but not at the positive. Potassium and sodium alloy, under the influence of the current, solidifies at both poles. Whatever the electro-chemical rank of a metal, if present in small quantities in the alloy, it goes always to the negative pole. The amalgams of gold and bismuth dissolved in mercury may be taken as examples. Whatever the amalgamated metal, it always returns to the negative pole.

II. APPLIED CHEMISTRY.-The manufacture of soda has lately received a new impetus by the discovery that a very slight additional trouble, in one stage of the operations, will enable a large quantity of the soda to be obtained in the pure caustic state; besides effecting a great saving in carriage, the product is obtained in a more concentrated and available form. Dr. Pauli has lately shown how this crude caustic soda may be obtained in the perfectly pure state on the large scale. Three tons of it are fused in a cast-iron pot, and the scum which rises to the surface is ladled off; several of the impurities are got rid of in this way. The pot is kept at a dull-red heat all night, and in the morning the mass appears perfectly transparent, the sides and bottom of the vessel being coated with cauliflower shaped crystals containing all other impurities originally present in the soda. The clear fused liquid is ladled off from these crystals, and, when cold, is ready for use. The caustic soda prepared in this way is hard and brittle, and can be easily obtained in fine powder; the only impurity which it is likely to contain being a trace of carbonate, it will doubtless prove a valuable reagent in manufacturing, and in chemical laboratories.

The application of chemical knowledge to the preservation of food has not received the attention which so important a subject deserves. One of the most ingenious adaptations of this sort is a plan devised by Mr. M'Call, who adopts the old plan of expelling air by boiling, but adds an ingenious contrivance of his own. All who have been condemned to live on preserved meats, are well aware that a little decomposition almost always

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