Abbildungen der Seite
PDF
EPUB

advances slowly; its cooled edges forming a passage for it, and keeping it elevated above the soil, and quite covered with scoriæ, so that its Auid portion is perceived with extreme difficulty. It is also well known that its heat in no respect approaches to that of melted glass; for, when it surrounds the trunks of trees, it does not char them to the centre. Hence M. de la Groye thinks that lava owes its fluidity to some principle which is consumed by the very act of fusion, and that this circumstance accounts for the difficulty of re-melting that which has cooled. The general mass, or that portion which is not swoln into scoriæ, has quite a stony aspect, and corresponds to the graustein of the Germans. The author compares the periods of the fusion of the lavas to those of the fusion of the salts after swelling ; and he relates curious facts with respect to the prodigious duration of their heat, whence he infers that they are endued with an intrinsic principle

of ignition, and not merely affected by a communicated heat.' To all these remarks, M. de la Groye subjoins a very detailed narrative of the

great eruption of 1813, which engendered an infinite quantity of lapilli and ashes, but of which the lavas did not extend to the cultivated grounds.'

This naturalist's opinion concerning the debateable mountain of Beaulieu, situated about three leagues from Aix in Provence, is that it is the remain of a submarine volcano.Another fall of stones, accompanied with the usual circumstances, is confidently asserted to have taken place at Langres.

Botany. - The Baron de Beauvois has not only gathered the ripe seeds of the Lemna, but succeeded in making them germinate; and, by watching the entire progress of the plants thus obtained, he has completed their history, which Micheli, Ehrhardt, and Wolf had only sketched. -- M. Decandolle endeavours to shew that the deformity termed ergot, or spur, in rye, and some of the other gramina, is produced by a parasitical fungus, appertaining to the genus sclerotium. As it is frequently the cause of serious disorders to the inhabitants of the districts in which it prevails, various modes have been proposed for its extirpation: but the most effectual, according to the present writer, would be the enforcement of an obligation on the proprietors to produce, once in a year, a certain measure of the diseased grain, which should be consigned to the flames on delivery.

Zoology, Anatomy, and Physiology.- M. Latreille has offered detailed descriptions of certain Crabs of the Mediterranean, remarkable for the long and two-jointed tubes at the extremity of which their eyes are placed, and which they move like tlie branches of a telegraph. Some of the species had been already noticed by MM. Rondelet and Aldrovandus; who, however, made no mention of the singular structure of

their organs of vision. M. Latreille includes them in a genus which he denominates Hippo-carcinus, and Dr. Leach has ranked them under the term Homolus.- MM. Latreille and la Billardière have distinctly traced the ticking noise, familiarly known by the expression death-watch, to a female Anobium, on the wood of our apartments.

Medicine and Surgery. — As this section refers entirely to topics already sufficiently promulgated in the public journals, or in the separate works in which they are fully discussed, (for example, Larrey's Memoirs of Military Surgery, and Orfila's Treatise on Poisons,) we refrain from any fartber notice of its contents.

WE

Art. XI. Mémoires de l'Académie Royale, &c.; i.e. Memoirs of

the Royal Academy of Sciences in the Institute of France, for the Year 1816. Vol. I.

[Art. concluded from the last Appendix.] E must now also complete our report of this volume,

adverting in like manner to M. Curier's Analysis of the Labours of the

Physical Class. Physics and Chemistry. - We observe a brief allusion to MM. Robiquets and Colin's experiments on the olefiant gas, and to M. Chevreul's continued experiments on fatty substances. Some of the main conclusions, at which this laborious chemist has arrived, are, that hog's lard is composed of two principles : the one, of some degree of consistency, and the other more liquid; that the action of alkalies alters their combination, elicits from them a new principle analogous to the sweet body of Scheele, and gives rise to the formation of two other principles of an acid nature, with which the alkali combines to form soap, &c. M. Chevreul, moreover, enters on the investigation of the causes to which certain oils and fats owe their consistency, odours, and colours; limiting his researches chiefly to the fat of the human subject, the ox, the sheep, the jaguar, and the goose. The varieties, with respect to consistency, depend on the proportions of the two general principles of fat bodies, while the other differences originate in particular and extraneous principles. Finally, he purposes to express the principles which he professes to have discovered, and their combinations, by language adapted to the chemical nomenclature.

Mineralogy and Geology. The discovery of sodalite in Greenland, where its repository indicates no vestige of volcanic agency, and in the Fossa grande of Mount Vesuvius, is a circumstance worthy of the consideration of reflecting geologists. App. Rɛv. VOL. XCI.

M. Bro

Mm

M. Brochant's able exposition of the transition-rocks in the Tarentaise, has derived confirmation from the discovery of certain shells which had at first escaped observation. He has subsequently extended his range of observation to the antient gypsum which occurs abundantly in some districts of the Alps, and to which he assigns the same intermediate station. The reporter observes:

• It is not always easy to characterize the primitive countries themselves : the irregularity of their position, the vast extent of space over which we are sometimes necessitated to trace their relations, and the graduated variations of their composition, presenting great difficulties. Thus M. Brochant has ascertained, in consequence of long journeys and laborious examinations, that the lofty summits of the Alps from Mont Cenis to Saint-Gothard, and especially Mont-Blanc, are not, according to previous conjecture, granite properly so called, but a mere crystalline variety, and more abounding in felspar, of a talcaceous and felspatose rock; which predominates in a considerably extensive portion of the Alps ; and which often contains metallic ores, disposed in strata. He is, at the same time, convinced that a genuine granitic territory prevails on the southern border of the chain ; and, reasoning from analogy, he deems it extremely probable that this granitic region supports the talcaceous one : whence he concludes that the high summits of the Alps are not, relatively speaking, the most antient portion of these mountains.'

M. Ramond has given an account of an analogous disposition of the rocks in the Pyrenees. The names of de Serres and de Férussac are again cited, in conjunction with that of Professor Beudant, of Marseilles, on the subject of fossil terrestrial and marine shells. The experiments of the lastmentioned naturalist shew that, although an abrupt transference from fresh to salt water, or vice versá, proves fatal to the inhabitants of many species, several are capable of being habituated to a gradual change of element in this respect; while others cannot resist the slightest variation of the water in which they reside. M. Moreau de Jonnes presents a geological map of a portion of Martinique, and has extended his researches to several of the West India islands, which appear to have been the theatre of extensive volcanic action.

Botany and Vegetable Physics. — The gradual publication of the ample botanical treasures amassed by the intrepid Humboldt is announced, under this head, in terms commensurate to the magnitude and generosity of the design. The Baron de Beauvois, availing himself of the unusual humidity of the season, discovered several species of fungi which had eluded the search of preceding botanists; particularly a variety of Sclerotium, which destroyed entire crops of unpropped French beans; a spheria, an uredo, and a non-deseript parasite of a parasite, which is reserved for the subject of a future communication. M. Virey has been induced to controvert the fungous character of the spur in rye, as asserted by M. Decandolle ; and the question, from some recent chemical experiments, seems to be still open to discussion.

beans;

Zoology, Anatomy, and Animal Physiology.-M. Cuvier here traces the outlines of M. Latreille's estimable work on the Climates of Insects, with which, it is to be presumed, the scientific public of this country will soon be better acquainted. - He next apprizes us of the dissection of the Hottentot Venus, who was exhibited at Paris. The peculiarity of this individual's organization consisted in a considerable prolongation of the upper part of the nympha, and which covered the vulva. The remarkable prominence of the hips was formed of cellular texture, filled up with fat; the margin of the pelvis was a little thicker and wider than usual; the skull presented a singular mixture of the characteristics of the Negro and of the Calmuck; and the bones of the arm were uncommonly slender. M. Moreau de Jonnès communicates a memoir on the highly venomous reptile, called Yellow Viper of Martinique, which particularly multiplies among the sugar-canes ; and for the extirpation of which he proposes the services of the Secretary-bird, or Serpent-eater; those of English terriers, having proved ineffectual. - With a view to determine the problem of the origin of azote in the animal system, M. Magendie fed dogs on substances which contain no perceptible quantity of azote, such as sugar, gum, olive-oil, butter, and distilled water. These animals all died in consequence; and their dissolution was accompanied by very singular appearances, particularly by an ulceration of the cornea, which sometimes perforated that membrane so that the humours of the eye were discharged through the opening. Their secretions assumed the characters of those of the herbivorous tribes, their azotic principle quickly diminished, and the volume of their muscles was reduced to one-sixth of the ordinary dimensions. These symptoms did not proceed from defect of digestion, because the unazotic aliments produced chyle, and filled the lacteals. Azote enters as a constituent part into the composition of urea, and into uric acid, those elements of calculus in the bladder; and, as these matters suffer sensible diminution in the urine of animals fed on substances free from azote, M. Magendie infers that, in consequence of a strictly vegetable diet, the progress of the stone may be at least considerably retarded. Perseverance in a vegetable regimen, however, has a tendency to induce diabetes, which is not so M m 2

easily

easily cured as the Secretary's cool remark would seem to imply.

Medicine and Surgery. M. Larrey, so justly celebrated for the extent and complication of his hospital-practice, has communicated some valuable information with respect to the introduction of extraneous bodies into the chest, and the means of extracting them. He likewise exhibited a successful instance of amputation of the thigh at the upper joint.

Rural Economy, and Technology. Guichardière, a hatter in Paris, has discovered that the hair of the land and marine otter may be advantageously used for that of the beaver, in the manufacture of hats; and that, by mixing it with hair of a more ordinary quality, the expence may be considerably reduced.

The Report concludes with the Eloge of M. Tenon, whose life presents the affecting but consoling lesson of the triumph of worth and talent over the indigence and obscurity of youth ; and that of temperance and skilful regimen over original delicacy of constitution. This estimable man was born at Scepeaux, near Joigny, on the 21st of February, 1724, and died on the 18th of January, 1816. His professional history, especially as connected with that of the medical and chirurgical institutions, and with the former revolting abuses of the hospital.practice of Paris, is unfolded with impressive energy; and we rise from the perusal of the document with sentiments of respect for M. Tenon's abilities, and for his unwearied adherence to the line of rectitude and honour. As, however, he bequeathed to the Secretary the memoirs of his life, and as he was long conversant among his learned associates, we could have welcomed a more unreserved disclosure of the tenor of his private existence; together with more traits and anecdotes, illustrative of his familiar deportment and conceptions; such exhibitions of native character forming the principal charms of biography, although they are too often supposed to derogate from the unbending dignity of an academical panegyric.

One MEMOIR also remains for notice.

On the Sugar of Beet-root. By Count CHAPTAL. -- During - their want of ships and colonies, the French were stimulated to explore and cultivate their internal resources of agriculture, commerce, and arts, and struggled to become independent of foreign countries for various articles of luxury or comfort. In particular, they laboured, with various success, to obtain sugar from honey, grapes, and beet-root; especially from the last, which was found to yield it of the best quality, and in the greatest abundance. The analyses of M. Marcgraaf, and the experiments of M. Achard, had prepared the way for this

« ZurückWeiter »