new kind of matter. But the observations of Angström, Roscoe, and Clifton, and recently those of Schuster regarding the spectrum of nitrogen, render it probable that elementary bodies have only one spectrum: and since in all experimental spectra we necessarily operate only on a small thickness of a substance, we cannot say what new lines may be given out in cases where there is an immense thickness of vapour; and hence we cannot conclude with certainty that because there is an unknown line in the chromosphere or corona, it implies a new substance."

On the photographic evidence respecting the corona, Dr. De la Rue remarks, "If the rays and rifts were really atmospheric, it would hardly be possible that they should present the same appearance at different stations along the line of totality; indeed they would probably change their appearance every moment, even at the same station. If they are cislunar, the same appearances could not be recorded at distant stations. It is universally admitted that proof of the invariability of these markings, and especially of their identity as seen at widely separated stations, would amount to a demonstration of their extraterrestrial origin. Eye-sketches cannot be depended on; the drawings made by persons standing side by side differ often to an extent that is most perplexing. Now photographs have, undoubtedly, as yet failed to catch many of the faint markings and delicate details; but their testimony, as far as it goes, is unimpeachable. In 1870, Lord Lindsay at Santa Maria, Professor Winlock at Jerez, Mr. Brothers at Syracuse, obtained pictures, some of which, on account partly of the unsatisfactory state of the weather, could not compare with Mr. Brothers's picture obtained with an instrument of special construction; * but all show one deep rift especially, which seemed to cut down through both the outer and inner corona clear to the limb of the moon. Even to the naked eye it was one of the most conspicuous features of the eclipse. Many other points of detail also come out identical in the Spanish and Sicilian pictures.

"None of the photographs of 1871, by Colonel Tennant and Lord Lindsay's photographic assistant, Mr. Davis, shows so great an extension of the corona as is seen in Mr. Brothers's photograph, taken at Syracuse in 1870; but, on the other hand, the coronal features are perfectly defined on the several pictures, and the number of the photographs renders the value of the series singularly great. . . . We have in all the views the same extensive corona, with persistent rifts similarly situated. Moreover, there is additional evidence indicated by the motion of the moon across the solar atmospheric appendages, proving, in a similar manner as in 1860 in reference to the protuberances, the solar origin of that part of the corona."

The Sun's Complex Atmosphere.-Dr. De la Rue says, "On the long disputed question of the complex atmosphere below the chromosphere, in connection with the solution of the most prominent questions connected with

"Mr. Brothers had, in 1870, the happy idea to employ a so-called rapid rectilinear photographic lens, made by Dallmeyer, of 4 inches aperture and 30 inches focal length, mounted equatorially, and driven by clockwork; and he was followed in this matter by both Col. Tennant and Lord Lindsay in 1871. The focal image produced, however, is far too small (% of an inch, about); therefore it will be desirable in future to prepare lenses of similar construction, but of longer focal length and corresponding aperture.'

the solar envelopes, it may not be without great interest to allude another point conclusively decided during the last annular eclipse of the sun, observed by Mr. Pogson on June 6 of this year, as described by him in a letter to Sir George B. Airy. In 1870 Professor Young was the first to observe the reversal of the Fraunhofer lines in the stratum closest to the sun. Now, in 1871 doubts were thrown upon the subject. It appears that the reversed lines seem to have been satisfactorily observed by Captain Maclear at Bekul, Colonel Tennant at Dodabetta, and Captain Fyers at Jaffna. The observations of Pringle at Bekul, Respighi at Poodacottah, and Pogson at Avenashi were doubtful, while Mosely at Trincomalee saw nothing of this reversal, which is, according to all accounts, a most striking phenomenon, although of very short duration. Mr. Lockyer missed it by an accidental derangement of the telescope. The reversal and the physical deductions from it are placed beyond doubt by Mr. Pogson's observations of the annular eclipse on June 6. At the first internal contact, just after a peep in the finder had shown the moon's limb lighted up by the corona, he saw all the dark lines reversed and bright, but for less than two seconds. The sight of beauty above all was, however, the reversion of the lines at the breaking up of the limb. The duration was astonishing-five to seven seconds; and the fading out was gradual, not momentary. This does not accord with Captain Maclear's observations in 1870, who reports the disappearance of the bright spectrum as 'not instantly, but so rapidly that I could not make out the order of their going.' Professor Young, again, says that they flashed out like the stars from a rocket-head.' But discrepancies in this minor point may be accounted for by supposing differences in quietude of that portion of the sun's limb last covered by the moon."

Dr. Huggins's Spectroscopic Observations of Nebula.—On this subject Dr. De la Rue remarks: "Although, as I have stated, I do not contemplate passing in review recent discoveries in astronomy, I must not omit to call your attention to some few subjects of engrossing interest. First, with reference to the more recent work of Dr. Huggins. In his observations he found that the brightest line of the three bright lines which constitute the spectrum of the gaseous nebula was coincident with the brightest of the lines of the spectrum of nitrogen; but the aperture of his telescope did not permit him to ascertain whether the line in the nebula was double, as is the case with the line of nitrogen. With the large telescope placed in his hands by the Royal Society, he has found that the line in the nebulæ is not double, and in the case of the great nebula in Orion it coincides in position with the less refrangible of the two lines which make up the corresponding nitrogen-line. He has not yet been able to find a condition of luminous nitrogen in which the line of this gas is single and narrow and defined like the nebular line."

Stellar Motions of Recess and Approach—“Dr. Huggins has extended," says Dr. De la Rue, "the method of detecting a star's motion in the line of sight by a change of refrangibility in the line of a terrestrial substance existing on the star to about 30 stars besides Sirius. The comparisons have been made with lines of hydrogen, magnesium, and sodium. In consequence of the extreme difficulty of the investigation, the numerical velocities of the stars have been obtained by estimation, and are to be regarded as provisional

only. It will be observed that, speaking generally, the stars which the spectroscope shows to be moving from the earth, as Sirius, Betelgeux, Rigel, Procyon, are situated in a part of the heavens opposite to Hercules, towards which the sun is advancing; while the stars in the neighbourhood of this region, as Arcturus, Vega, and a Cygni, show a motion of approach. There are, however, in the stars already observed, exceptions to this general statement; and there are some other considerations, as the relative velocities of the stars, which appear to show that the sun's motion in space is not the only or even in all cases the chief cause of the observed proper motions of the stars. In the observed stellar motions we have to do probably with two other independent motions-namely, a movement common to certain groups of stars and also a motion peculiar to each star. Thus the stars ß, 7, d, e, 2 of the Great Bear, which have similar proper motions, have a common motion of recession; while the star a of the same constellation, which has a proper motion in the opposite direction, is shown by the spectroscope to be approaching the earth. From further researches in this direction, and from an investigation of the motions of stars in the line of sight in conjunction with their proper motions at right angles to the visual direction obtained by the ordinary methods, we may hope to gain some definite knowledge of the constitution of the heavens. This discovery supports, in a somewhat striking manner, "proceeds Dr. De la Rue, "the views which Mr. Proctor has been urging respecting the distribution of the stars in space."

BOTANY.

The Geographical Distribution of Compositæ.-Mr. G. Bentham read a paper on this subject at two meetings of the Linnæan Society, in continuation of his paper on the structure of the same order of plants. The genera and species of this largest order of flowering plants are about equally distributed between the Old and New World; of the genera, about 410 are found in the former and 430 in the latter; of species, about 4,400 in the Old World and a rather larger number in the New. Not quite 70 species are common to the two hemispheres, and these mostly belong to the extreme northern regions; a few are common to New Zealand and Antarctic America; not more than a dozen tropical species are found in both the Old and New World, and some of these are coast plants. The form which Mr. Bentham looks on as prototypic, and possibly ancestral to the whole order, includes a few closely allied genera, distinguished by their regular corolla, belonging rather more to the American than the Old World distribution, being found in Chili, with an outlying genus in St. Helena. Other types, apparently of great antiquity, are found in Africa, Australia, and Western America. Since the separation of the Indo-Malayan and Australian regions from one another, there appears to have been a continuity of races of Compositæ across the tropics from south to north. The paper, which enters exhaustively into the distribution of the various tribes and more important genera, is published in the "Journal of the Linnæan Society."

The Formation of Ozone by Flowers.-It is stated by the Academy that Mantegazza has found (“Rendiconti del Reale Instituto Lombardo,” vol. iii. fasc. vi., abstracted in "Der Naturforscher," April 27) that many essential oils, like that of peppermint, turpentine, oil of cloves, lavender, bergamot, aniseed, nutmeg, thyme, and others, when in contact with the oxygen of the atmosphere in presence of sunlight, develop very large quantities of ozone. The oxidation of these oils is, in fact, a very convenient source of ozone, as they, even in small quantities, ozonise much oxygen. The action is strongest in direct sunlight, far less so in suffused daylight, and very weak or at an end in the dark. The development of ozone which has been begun in the light continues for a long time in darkness. In the same manner act eau-de-cologne, hydromel, and other aromatic tinctures on exposure to the solar rays. Experiments which Mantegazza has made on flowers with powerful perfume, such as the narcissus, hyacinth, heliotrope, mignonette, and others, in closed vessels, proved that they also form ozone. Those with fainter perfume produced less ozone, those without scent none at all. Mantegazza believes that this important source of ozone is of hygienic value for the purification of the air of marshy districts.

Absorption of Water by Leaves under certain circumstances.—The statements of Duchartre and others, that leaves absorb neither water with which they are wetted nor vapour from surrounding air, have been fully confirmed by M. Cailletet so far as respects the foliage of plants established in the soil and supplied with moisture by the roots. But the revival of wilting leaves when sprinkled or enclosed in a moist atmosphere, however ingeniously explained away, always seemed to bear testimony to absorption. And M. Cailletet's experiments go to show, incontestably, that foliage does absorb liquid water (but not watery vapour) when supply by the root fails or is arrested. His experiments were made by introducing a leafy branch into a glass vessel with a double tubulure, filled with water, the increase or diminution of which was accurately and delicately measured by a manometer. A Bromeliaceous epiphyte, which grew under his care for six years, suspended by a fine wire without root, he found, was able to absorb and fix more than a hundredth part of its weight of water upon a short immersion. His note upon the subject was presented to the French Academy, and is printed in "Ann. Sci. Nat.," vol. xiv. p. 243. Change of Habit. It is stated in "The Garden," that the Loranthus macranthus of New Zealand, parasitic there upon trees of Rutacea and Violacea, is deserting these in favour of trees introduced by the European settlers, such as hawthorn, plum, peach, and especially laburnum, which was introduced as lately as 1859. Its flowers are abundantly visited by the European honey-bee.

Double Flowers of Ranunculus Rhomboideus.-A correspondent of the "American Naturalist" has found several perfect double flowers of this plant in Floyd County, Iowa. One of them was transferred to a bed in the flower-garden, where it throve well, and increased to a clump six inches in diameter, which, the next spring, was perfectly enveloped with the little bright yellow flowers. No seeds were produced; and during the two or three seasons in which the plant was cared for there was no sign

of change to single flowers. The plant was quite attractive; and as it blooms very early and profusely, it would seem to have some of the qualities required to entitle it to a place among cultivated flowers.

CHEMISTRY.

Detection of Nitrogenised Matter in the Atmosphere.—Mr. A. H. Smee has described ("Chemical News," July 19) a method which he has devised, and which he names "distillation by cold," by which he believes the detection and determination of ammonia and other organic impurities existing in the atmosphere will be greatly facilitated. A glass funnel (usually of 8 or 9 inches) is drawn to a point and closed. It is supported in an ordinary stand, and filled with ice. Condensation of the watery vapour of the atmosphere then takes place; the dew collects into drops, which trickle down the outside of the funnel, and at last fall from the point, under which a small receiver is placed to catch them. The total quantity of liquid collected in a given time is measured, aud the quantity of ammonia determined by Nessler's test. By the method of distillation by cold, the author found it possible to distil many substances which are decomposed at a high temperature. Thus many delicate odours of flowers were distilled by placing the flowers under a bell-glass sufficiently large to cover the funnel containing the ice. The odours were found to be more rapidly and completely abstracted by placing a dish with a little ether under the bell-glass at the time of distillation. The paper was accompanied by tables giving the results obtained in 107 experiments, together with the atmospheric conditions prevailing at the time. The experiments were made in a garden, in a bed-room, in hospital wards, in the open country, &c.

A Method of obtaining Potassium.-Professor A. Dolbear has described the following mode :-Some white stick caustic potash of commerce is dissolved in water and then treated with sulphuretted hydrogen in the way commonly described for making potassium sulphide, K,S. The solution is evaporated until it is solid when cool, when the yellowish mass is mixed with more than its bulk of iron filings and chips, and the whole put into an alembic for distillation. The heat of a furnace is applied till the alembic is of a bright red heat, and the products of distillation are received in common coal oil. The product is rather small, as some of the potassium vapour decomposes the heated vessel; nevertheless the potassium shows itself when the oil is poured off, and the residuum turned upon water, by its characteristic ignition and flame. The reaction is simple, and may be thus represented. K2S+ Fe = FeS + K2.

Chemical Action during a number of Years.-In the "Comptes Rendus," July 8, M. Becquerel has a paper which contains the account of the results of some experiments which prove that, by slow but continued action, curious effects may be obtained; for instance: Crystals of arragonite are formed upon a piece of gypsum (lance-shaped variety) kept in a closed vessel in a solution of bicarbonate of potassa; the gypsum has almost entirely disappeared, having become converted into arragonite. A similar piece of