relative to the theory of differential equations raised, and to the multiplicity of their integers. The commissioners MM. la Place and Prony speak with great respect of this memoir, and the author's other labours. M. Biot seems to be a young man of considerable promise, and has since, we apprehend, been elected member of the National Institute.

The next class is that of Mechanic Arts; and we find a report of a new Telegraph, the invention of MM. Bréguet and Brétancourt, by MM. la Grange, la Place, Borda, Prony, Coulomb, Charles, and Delambre. The machine is peculiarly simple, consisting only of a perpendicular and a moveable arm, called the arrow. The position of the arrow, and the angle it makes with the horizon, express whatever is wanted from the telegraph. The commissioners speak of it with much respect; and, by the addition of lanterns, it is adapted for conveying intelligence by night. A plate would have greatly facilitated the comprehension of the reader.

In the class of Philosophy, we find the remarks of M. Baussard on the Tides of Teneriffe, who found them very irregular. Lalande fixed the period of high water at noon. Other authors have supposed it to be at three o'clock. We suspect Lalande to be nearest the truth.

In the class of Chemistry, there is a report on a memoir of M. Cossigny, by MM. Fourcroy and Guyton. Its object is to recommend the cultivation of woad in the Isle of France, from which he proposes to prepare a true indigo. A similar substance may, it is said, be obtained from the blue scabious. The memoir, however, affords no certain process or plan, but only proposals and inquiries; and the author seems unacquainted with the latest and best works on the subject. On the whole, the commissioners applaud his zeal and patriotism, and wish him to pursue the inquiries more pointedly and scientifically. • We next find a report by MM. Bayen, Pelletier, Vauquelin, Chaussier, and Lelievre, on a metallic ingot, sent to the legisla tive body by the Commission of Finances. They requested to know its composition, and whether it could be imitated. The object we are unacquainted with. The metal was white, and, when broken or filed, the colour was yellowish; its specific gravity 9.4776. The commissioners found it composed of nearly equal parts of silver and copper, with a very little arsenic, and about 0.04 of gold.

An Abstract of a Report respecting Colours for Porcelain, by M. Dihl,' follows. The great object pursued is to discover substances whose colour will not change by vitrification. Few of these only have hitherto been known, and the preparation has been generally concealed. The commissioners, MM. Fourcroy, Darcet, and Guyton, think that the author has in general succeeded, and greatly extended our knowledge in this branch of chemistry.

The same colours appear, in their opinion, to be equally useful in painting in oil, on cloth and other substances, and to be scarcely impaired by time or the usual causes of imperfection.

The history of the prizes follows, of which few have been distributed: of the first three questions no candidate has appeared for the two former. That on the orbit of a comet was fully answered by Burckhard. The titles of the memoirs which the Institute think worthy of being printed in the Memoirs of the Savans Etrangers are next introduced; and to these succeed the inventions, machines, and preparations approved by the society, and a list of the printed books presented to it. The éloges are those of the venerable Daubenton and of Lémonnier, by M. Cuvier. The life of Daubenton is peculiarly valuable; and we regret that we cannot, from its extent, notice even the leading facts.

The first memoir is that so often mentioned, An Inquiry into the Laws of Affinity, by M. Bertholet,' which is conti-nued in different parts of the volume. The second is entitled Chemical Considerations on the Use of Oxyds of Iron in dying Cotton, by M. Chaptal.' Cotton has a very considerable affinity with oxyd of iron, so as to attract the whole of it from a bath. It is usually employed in a state of solution; and the acetous, or any of the mineral acids, is resorted to for this p purpose. The acetous is preferred chiefly, because it does not destroy the cloth, as the other metallic salts will do, unless it be immediately immersed in water. M. Chaptal proceeds to show what colour the oxyd of iron will produce, without addition or preparation, or when employed with madder or the astringent principle. The colour of iron is a very solid one; but so greedy is the cotton of this colour, that it soon becomes harsh to the eye, and injures the stuff. The colour which it gives is the shammy. When the iron is precipitated, the colour is of a dirty irregular green, which however soon becomes yellow. The management of this colour, so that it may unite with the softer and more uniform colour of vegetables, is particularly described. The management of the iron with the astringent principle is also interesting, but too long for this place. It has -been supposed, that, by increasing the proportions of sumach, salder, or the green oak, the use of galls may be superseded. This is indeed the case with wool or silk; but with cotton the icolour is dry, thin, and less solid.

III. A Memoir on the Motions of the Orbits of the Satellites of Saturn and Uranus (the Georgium Sidus), by M. la Place.' On comparing the results of the observations of Cassini and Bernard, Lalande concluded that the node of the orbit of the last satellite of the former planet, which is not like those of the first six satellites in the plane of the-ring, but a little inclined to it, had gone back, in the period of seventy-three years, 60° 50′, about 5' 37" annually. M. la Place, in the present memoir, inquires

what would be the result of the theory of gravitation. He finds that the first six satellites are kept in the same plane by the attraction of Saturn and his rings; but the distance, and perhaps the size of the seventh, renders it subject to other powers, and particularly of the Sun. The subject, however, is pursued in too minute and scientific analysis for an abstract; nor have the observations been yet sufficiently numerous or exact.

'IV and V. Second and third Memoirs on the Use and Utility of Mercurial Preparations in the Small-Pox, by M. Dessessartz.' The first memoir on this subject we noticed in our 33d volume, p. 479. In the second, the author examines the question historically; that is, he traces, in different authors, numerous instances in which mercury has been given previous to the disease, and on its appearance. In these the eruptions have either not appeared, of been remarkably few, and the whole disease peculiarly mild. The event the author, after an inquiry somewhat too minute and prolix, thinks to be owing to the medicine, as a specific. The facts advanced are, at least, numerous and valuable. In the third memoir, our author endeavours to show that the mineral preparation has been, in his own practice, successful, and lays down the rules for conducting it. Our medical readers, and particularly the advocates for the cow-pox, will not expect us to detail more particularly the plans of M. Dessessartz laid down in the memoir before us.

'VI. A theoretical and practical Determination of the Powers which bring different Needles, saturated with Magnetism, to the magnetic Meridian, by M. Coulomb.' This memoir is supplementary to the author's former labours, which we were unable to follow, from the difficulty of abridgement, and the impossibility of extracting any part with advantage. Whatever be the nature of the magnetic fluid, the author finds, that, from its known laws, it may be subjected to calculation.

VII. Memoir on the Theory of the Moon, by M. la Place.' This very scientific memoir relates to a motion of nutation in the lunar orbit, analogous to that of the terrestrial equator, the period of which is that of the motion of the nodes of the moon. The terrestrial spheroid, by its attraction on the satellite, produces an oscillation on the lunar orbit, as the attraction of the moon produces an oscillation on our equator.

VIII. Experiments to ascertain the Cohesion of Fluids, and the Laws of their Resistance, in very slow Motions, by M. Coulomb' This memoir is truly excellent; but the whole depends on minute experiments and calculation, so that we cannot even convey a faint idea of it.

IX. A Memoir on the Cupellation of Lead, in the great Way, containing some Reflexions on the Inconveniences resulting from the Cupels made from Ashes; followed by a new economical Method of constructing these Cupels; by M. Duhamel.'

The cupellation of lead is the mean of separating the silver from it; and the principle on which this is effected is the property of the glass of lead to penetrate different substances, and leave the silver, which, in the same heat, will not be oxydated. The vessels in which this is performed are called cupels, and are made from the ashes of bones or of wood. As they are soon saturated with the lead, they are expensive in the usual management. Other methods have been adopted in England; and our author refines still further upon them.

pro

'X. An Essay on the Analysis and Re-composition of the two fixed Alkalis, and of some of the Earths supposed to be simple, by MM. Guyton and Desormes.' We announced this discovery some time since; but we own that we expected a more detailed and more scientific support of it. The whole amounts to little more than suspicion-yet a suspicion not wholly without foun dation; the great principle of which is, that, in different cesses with kali and soda, lime and magnesia respectively appeared; and on repeating the experiment with the same alkalis, there seemed to be no limits to the appearance of the two earths. Many of M. Desormes' arguments are derived from the changes produced in consequence of vegetation. These, though deserving a better appellation than theoretical, are however not so clearly established as to afford a sufficient foundation to a doctrine whose influence would be very extensive. We shall translate what M. Guyton remarks from himself. It is almost the whole of his share of the memoir, which more particularly refers to the subject.

New processes have been employed. They have been var ried and repeated frequently; and, to confine the conclusion to precise facts, there can be no doubt that, by treating pot-ash with different chemical agents, when the salt is perfectly pure, lime may be separated, and that the operations which pro duce this consequence are those in which the affinities of hydrogen are chiefly conspicuous. I owe this conviction to two experiments,

The first is the decomposition of oxygenated muriat of pot-ash by the phosphoric acid. Infusing this mixture in a crucible of platina, the mass is re-dissolved; and if the excess of acid be saturated with ammonia, a phosphat of lime is precipitated; and this operation may be repeatedly performed on the same quantity of muriat, without any diminution of the product. The second experiment is a process in which pot-ash infusion acts on charcoal. A considerable portion assumes the form of carbonic acid; and the combustion of hydrogen is visi ble, which cannot be renewed by adding water to the mixture when the pot-ash is saturated with carbonic acid: the remainder

is pot-ash in the state of carbonate; and lime, which the oxalic acid immediately separates from the nitric.'

The rest of the article, we have said, consists of what may be styled presumptive proofs, and experiments by no means conclusive. We have not found that the subject has been reconsidered; and, indeed, doubts will easily suggest themselves to the experienced chemist. We must however wait for the result of further and more decisive experiments.

• XI. Memoir on the Changes which take place in the Organs of Circulation in the Fetus when it has once begun to breathe, by M. Sabatier. These doctrines are by no means new, though not generally known. Instead of the right and left auricle of the heart forming one cavity by means of the foramen ovale, in order that the blood from the placenta may be mixed with that which has passed through the lungs, M. Sabatier thinks that the blood from the lower vena cava passes into the left auricle, and that from the superior into the right; so that all the blood returns, secondarily, to the placenta before it has re-commenced its course, nearly as in the adult: it traverses the whole of the aorta; and the fluid, in its circulation, describes the figure of 8. This doctrine was published by the author in 1774, in the Memoirs of the Academy, and has been repeated in different publications; but is not very generally known, except on the continent. The cause of the commencement of respiration is examined somewhat more accurately than in other writers, but more diffusely. The principle of M. Sabatier is, that, from the difference of position, the abdominal viscera fall down, and draw with them the diaphragm; thus expanding the lungs, and bringing the intercostal muscles, by consent, into action. The vessels of the lungs are thus more completely filled; and the blood is carried into the right auricle so copiously, that the valve of the foramen ovale is closed, and cannot admit the blood brought to it by the inferior cava. The proof of the falling down of the viscera, thus described, and its consequences, is drawn from a minute anatomical investigation of the direction of the aorta and its first ramifications. In the fetus, for instance, the common trunk of the subclavian and right carotid arises from the most elevated p part of the arch of the aorta; while the left subclavian answers' to its lowest part, contrary to what is observed in the adult. When the liver, too, was raised into the cavity of the thorax by pressing up the diaphragm, the hepatic veins were nearer to the foramen ovale, and the blood passed into the heart in an almost horizontal direction; but, after the liver had taken its proper situation, they were at a greater distance, and the passage was more oblique. For a similar reason, the canalis arteriosus makes, after birth, a more