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3. ON THE THERMAL WATERS OF CHAUDES AIGUES, IN THE DEPARTMENT DU CANTAL.-(M. Chevalier.)

The little village of Chaudes Aigues is situated to the south of St. Flour, on the border of a stream in a pleasant valley, surrounded by high mountains. Its mineral waters have long enjoyed some celebrity, but have fallen into medical disuse. At present establishments are forming for the reception of patients, and many circumstances combine to render the place agreeable and tempting, and so to favour the enterprise. The sources of the Par, which is the largest of all, yield 230 cubic metres and 4 decalitres every twenty-four hours; its temperature is at 80° C. (170° F.) It is this water which the inhabitants employ by means of ingeniously contrived conduits, which conduct it to the houses, to give warmth during the winter: in the summer they turn it away towards the river, that they may not be inconvenienced by its heat. This practice should be followed at other towns where there are sources of hot water, as at Plombières, Aix, &c. M. Berthier has calculated, that the water of the Par is equivalent, as a heating agent, to the wood which would be furnished by a forest of oaks 540 hectares (1334 acres) in area. The water of this spring is clear, limpid, and almost tasteless; it leaves a slight ochraceous film upon stones; it becomes spontaneously covered with a thin oily film, but may be retained a long time unaltered. It issues from massive sulphuret of iron, and its channels are obstructed by a deposit of the same substance.

The second spring is that of the mill of Ban. It flows over quartz, serving as the gangue for sulphuret of iron. This water is conducted to the hospital and several private houses, in the same manner, and for the same purpose, as the preceding water.

The third spring, that of the Grotto of the mill, is particular in this circumstance, that, though less hot than the others, it follows exactly the same changes of temperature. At its source it disengages carbonic acid mixed with oxygen and azote.

The Maison Felgère is in possession of four springs, one of which is at the temperature of 70° C. (158° F.) The water of the river, heated by all these streams, is said to be more favourable in exciting vegetation than other rivers.

These waters, besides being applied to heat apartments, are used also to cleanse wool, and M. Felgère has formed an establishment for the hatching of eggs, in imitation of that arranged by M. d'Arcet, at Vichey.

M. Chevalier has obtained, by chemical analysis, from 20 litres (1220 cubic inches) of the Par water:-i. A trace of hydrosulphuret of ammonia, which appears to be formed by the action of heat. ii. An organic animalized matter, which appears as flocculi, when the water is evaporated, and sometimes occurs united to carbonate of lime. iii. 18.86 grammes (291 grs.) of a light solid substance, more than half composed of subcarbonate of soda. These waters, by their heat

and purity, are very analogous to those of Plombières, a circumstance in favour of the formation of a similar establishment*.

4. HUMBOLDT'S ACCOUNT OF THE GOLD AND PLATINA DISTRICT OF RUSSIA.

The following account is part of a letter from M. Humboldt to M. Arago: We spent a month in visiting the gold mines of Borisovsk, the malachite mines of Goumeselevski and of Tagilsk, and the washings of gold and platinum. We were astonished at the pepitas (waterworn masses) of gold, from 2 to 3lbs., and even from 18 to 20lbs., found a few inches below the turf, where they had lain unknown for ages. The position and probable origin of these alluvia, mixed generally with fragments of greenstone, chlorite slate, and serpentine, was one of the principal objects of this journey. The gold annually procured from the washings amounts to 6000 kil. The discoveries beyond 59° and 60° latitude become very important. We possess the teeth of fossil elephants enveloped in these alluvia of auriferous sand. Their formation, consequent on local irruptions and on levellings, is, perhaps, even posterior to the destruction of the large animals. The amber and the lignites, which we discovered on the eastern side of the Ural, are decidedly more ancient. With the auriferous sand are found grains of cinnabar, native copper, ceylanites, garnets, little white zircons as brilliant as diamonds, anatase, alvite, &c. It is very remarkable, that in the middle and northern parts of the Ural, the platinum is found in abundance only on the western European side. The rich gold-washings of the Demidov family, at Nijneï-tagilsk, are on the Asiatic side, on the two acclivities of the Bartiraya, where the alluvium of Vilkni alone has already produced more than 2800lbs. of gold.

The platinum is found about a league to the east of the line of the separation of waters (which must not be confounded with the axis of the high summits), on the European side, near the course of the Oulka, at Sukoi Visnin, and at Martian. M. Schvetsov, who had the good fortune to study under Berthier, and whose learning and activity have been most useful during our travels in the Ural, discovered chromate of iron, containing grains of platinum, which an able chemist at Catherineburgh, M. Helm, has analyzed. The washings of platinum at Nijneï-Tagilsk are so rich, that 100 puds (about 400 lbs. Russian) of sand afford 30 (sometimes 50) solotniks of platinum, whilst the rich alluvia of gold at Vilkni, and other gold washings on the Asiatic side, do not give more than 1 to 2 solotniks in 100 puds of sand. In South America, a very low chain of the Cordilleras, that of Cali, also separates the auriferous and non-platiniferous sands of the eastern declivity (Popayan), from the sands of the isthmus of the Raspadura of Choco, which are very rich in platinum as well as gold. M. Bousingault may, perhaps, already have thrown a new

Bib. Univ. 1830, p. 220.

light on this American formation, and his observations will derive some additional interest from those which we have made in this place. We possess pepitas of platinum, of many inches in length, in which M. Rose has discovered beautiful groups of crystals of the metal.

'As to the greenstone porphyry of Laya, in which M. Engelhardt has observed little grains of platinum, we have examined it on the spot with much care, but the only metallic grains which we have been able to detect in the rocks of Laya, and in the greenstone of Mount Belayr-Gora, have appeared to M. Rose to be sulphuret of iron; this phenomenon will be a subject for new research. The work of M. Engelhardt on the Ural seemed to us to be worthy of much praise. Osmium and iridium have also a particular locality, not amongst the rich platiniferous alluvia of Nijnei-Tagilsk, but near Belemboyevski and Kichtem. I insist upon the geognostical characters drawn from the metals which accompany the grains of platinum at Choco, Brazil, and in the Ural." 米

5. PARROT'S EXPEDITION TO Ararat.

A scientific expedition set out from Dorpat some time since, under the direction of Dr. Parrot, charged with the examination of the country around Mount Ararat. After many fruitless attempts, Dr. Parrot arrived at the summit of Ararat, and measured the height of this celebrated mountain. He found it to be 16,200 feet in elevation, which makes it 1500 feet higher than Mont Blanc. Dr. Parrot caused a barometric levelling to be taken by M. Behaghel, one of his companions, of the whole route from Tiflis to Ararat, as well as of that which leads from this city, by Imerethi and Mingrelia, to the Kalch redoubt on the banks of the Black Sea; but his observations are not yet calculated. This traveller describes the western summit, which is the most elevated part of Ararat, as being a plain of about 150 paces in circumference; eastwards it communicates by a low plateau with the other summit, which is not so high; at about 1200 feet of elevation everything is covered with ice and snow. The instruments which Dr. Parrot had with him, consisted of a pendulum apparatus, a magnetic inclinatorium of ten inches, barometers, a surveying apparatus, &c. In point of astronomical instruments, the expedition was provided with a Reichenbach's theodolite of eight inches, an Arnold's chronometer and one of Maynie's, a Dollond telescope of three feet, and a Trongleton's sextant.

Dr. Parrot was accompanied, as we before mentioned, by MM. Behaghel, a mineralogist, Schiemann, a zoologist, and Hehn, a botanist-all three students in the university of Dorpat†.

6. CUTICULAR PORES OF PLANTS.

It is well known to botanists that the cuticle of most plants is furnished, especially on the leaves, with minute organs, the func

*Edin. Geog. Journ. ii. 441,

+ Ibid. iii. 38.

tion of which is a matter of conjecture, and the actual structure of which has given rise to much difference of opinion. These organs have received the names of pores, or glands, or stomata, according to the views of different observers; and while one class of botanists has considered them of unknown function and structure, others have contended that they are of the nature of pores, and that their office was, according to the one, to facilitate evaporation to the others, to assist in the process of respiration. Their function is obviously of so obscure a nature, that no direct experiments are likely to demonstrate exactly what it is; but their structure is a point upon which observation may be expected to cast some light. Mr. Bauer long ago represented these organs in the wheat, as perforations opening into a minute subcutaneous cavity, and as destined to afford a direct passage into the interior of a plant for those minute fungi, whose ravages are so well known in the form of what the farmers call the mildew in corn. Other observers have, however, doubted whether the supposed perforations always existed; and Mr. Lindley, in his lectures in the University of London, has repeatedly expressed his difficulties upon the subject. The fact is, that they are so minute, the tissue of which they consist is so exceedingly transparent, and it is so difficult to examine them, except by the aid of transmitted light, that it is not, perhaps, possible to determine positively in all cases whether a perforation exists or not. Mr. Robert Brown has recently published some observations upon them, from which it is to be collected that, in the opinion of that distinguished observer, the stomata are rather of the nature of glands than of pores, and are undoubtedly in many cases imperforate-evidently having in their disc a membrane which is more or less transparent, sometimes opaque, or very rarely coloured. The existence of colouring matter in the stomata is the only circumstance that could have enabled an observer to prove their imperforate nature; for, in colourless membranes, such as those of Crinum, in which the stomata are particularly large, the best microscopes, employed under the most favourable circumstances, show nothing but an apparent orifice, closed up occasionally by the dilatation of two glandular bodies placed beneath it. Mr. Brown states, what was certainly a very unexpected fact, that these bodies will often, in proteaceous plants, by their figure and position, or magnitude, with respect to the meshes of the cuticle, determine the limits or even affinities of genera, or natural sections.

7. SMUT IN CORN.

This substance, which has been sometimes considered a mere organic disease, but more usually a parasitical plant, analogous to that which causes the mildew and the rust, and which has been described under the names of Reticularia segetum, Uredo segetum, and Uredo carbo, has been lately the subject of a particular inquiry on the part of M. Adolphe Brongniart, who thus describes the parts in which this malady is found, and who adopts the opinion that it

is caused by the ravages of a kind of fungus.

The axis which

supports the glumes and floral organs of grasses, is formed of elongated cellular tissue, the cellules of which are placed close together, without sensible intercellular passages, and of fibro-vascular bundles of false trachea or ducts, and spiral vessels; in the fleshy mass, of which the smut consists, no structure of this sort is visible, at whatever time it is examined; but, for examining it satisfactorily, I have taken the plant at the earliest period when the spike is capable of being examined. At this time the fleshy mass is found to consist entirely of an uniform tissue, containing uniform four-sided cavities, separated by partitions formed of one or two layers of very minute cellules. These cavities, which, in organization, resemble the regular lacunæ observable in the cells of aquatic plants, are filled by a compact homogeneous mass, composed of very small granules, perfectly spherical and uniform in size; they were slightly adherent to each other, and of a greenish colour in spikes but little developed-distinct, or simply clustered towards the centre of each mass, and of a pale nut colour, in spikes which were a little developed finally, at a more advanced period, the cellular partitions disappear, the globules separate completely, and the whole mass is transformed into a cluster of powder, formed of very regular globules perfectly alike, black, and quite analogous to the reproductive bodies of other fungi.'

8. STRUCTURE OF LEAVES.

A memoir, by M. Adolphe Brongniart, upon the structure of leaves, and on their relation with the respiration of vegetables in air and water, has been read before the Academy of Sciences of Paris. The author states that the leaves of plants that live in the air have a totally different structure from those that are completely submerged, and that this difference in the structure of organs is in direct relation to the two principal functions of leaves, respiration and transpiration. In leaves exposed to air, the surface of the leaf is covered by an epidermis of uncertain thickness, formed of one or more layers of colourless cellules, closely packed together. This membrane is pierced with the pores usually known by the name of stomata. The doubts that have been entertained upon the existence of perforations in these stomata, M. Brongniart thinks he has removed, and that it is certain that in the centre of each stoma is an opening by which the outer air communicates with the parenchyma. This parenchyma is evidently the seat of respiration; for it is the part that changes colour in exercising this function, which becomes green by the absorption of the carbon of the carbonic acid of the atmosphere, and which is discoloured again in darkness by the combination of the carbon of its juices with the oxygen of the air. This parenchyma differs entirely from that of other organs by the numerous irregular cavities that it contains, which communicate with each other and the outer air by means of the openings of the

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