Imatges de pàgina
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parison of a great number of Bradley's observations, found it to be 7"; and, ainally, M. Burg, by a great number of Maskelyne's observations, has lastly fixed it at 6".8. The existence of the inequality, then, appears incontestable. M. LA Place at first found, by the theory of universal gravitation, that at the most it was 2' : but, having since ascertained the nutation of the lunar orbit, he perceives that its influence on this inequality is very sensible ; and he finds that its co-efficient is to that of the preceding. inequality of the movement in latitude, as nine times and an half the tangent of the mean inclination of the !unar orbit are to unity.

· This calculation gives 5".6, for the co-efficient, in the hypothesis of of the earth's oblateness: but it would be increased to

if this oblateness were 230; and, as all the observations give a smaller co-eflicient, they concur with those of the moon in latitude, to exclude the homogeneity of the earth. The co-efficient 69.8, found by M. Burg, answers to an oblateness of which differs but little from the oblateness given by the inequality of the movement in latitude. It seems, then, that the comparison of a great number of observations of the moon, as well in longitude as in latitude, is capable of determining this oblateness with as much precision as direct measures ; and it is remarkable that continued observation of the movements of this heavenly body discovers to us the figure of the earth, the roundness of which it made known to the first astronomers by its eclipses. It results, moreover, from these researches, that the gravitation of the moon towards the earth is not exactly directed towards the centre of that planet, and is composed of the attractions of all its parts : which circumstance affords a new confirmation of the reciprocal attraction of the particles of matter.

Such is the curious and important investigation contained in the beginning of this memoir. The remainder is the analytical solution, founded on formula demonstrated in the Mécanique céleste.

Experiments calculated to determine the coherence of Fluids, and the Laws of their Resistance in very slow Motions.

By M. COULOMB. - When a body is impinged by a fluid with consi. derable velocity, it appears by experiment that the resistance is proportional to the square of the velocity: but, in extremely slow motions, the resistance (which is no longer as the square of the velocity) is proportional to a function of that velocity; of which, when the velocity is increased, all the other terms, re

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lating lating to that which expresses the square of the velocity, disappear. As, however, supposing the velocity to be very small, the quantity representing it is also very small, it is difficult to find its value by the ordinary methods, and still more so to separate what belongs to the different terins of the formula. This being understood, the object of M. COULOMB in the present memoir is to fulfil the two following conditions:

1. To employ a kind of measure by which it is possible to determine, almost exactly, the smallest forces.

2. To give, at pleasure, to the bodies submitted to experiment, a degree of velocity so small, that the part of the resist. ance proportional to the square of the velocity may become comparable with the other terms of the function representing this resistance: or even, in certain cases, that the part of the resistance proportional to the square of the velocity should become so small, comparatively with the other terms, as to be safely neglected.

This is a very brief and imperfect account of M. COULOMB'S memoir ; yet it may serve to give a general idea of its object. The description of the apparatus, the analytical processes, the conclusions, &c. occupy sixty pages ; and the subject is to be farther pursued in a second paper.

On the Art of making Gun Flints. By M. DOLOMIEU.-This art, it appears from the present memoir, is confined to a few communes of France, and is very little practised. In the foreign countries also, which he had visited, the writer knows of no place where the art is exercised, except in the territory of Vicenza, and in a canton of Sicily.--The memoir contains an analysis and description of the flint (silex Pyromachus), a drawing of the few instruments used in the fabrication of gun-flints, and a description of the several processes.

On Mines. By M. MARESCOT, Associate.-The fortress of Mentz being menaced by the Austrians, the author of this memoir was sent to take the command of it : but, the Austrians retreating, he seized the opportunity of making certain experiments relative to mines. He had long entertained the notion that, if, instead of filling the stoves of the mines, a certain space was left about the charge, the effect would be increased ; and that the air inclosed in that space, being much dilated by the heat of the inflamed powder, would join its elastic force to that of the gas disengaged in the combustion. His idea was confirmed by experiments; which, although they did not give results so decisive as he hoped to obtain, yet sufficiently shewed that spaces left round the stoves augment the force of the powder, and that the augmentation has a maximum.--The departure of the

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author from Mentz prevented him from making more numerous and more satisfactory experiments.

-On the Passage of Mercury over the Sun, observed on the 1815 Floréal, 7th Year. By M. DELAMBRE.—

A long paper, full of difficult computations, which are interesting only to astronomers,

MEDICAL and CHEMICAL PAPERS. Inquiries concerning the Laws of Affinity. By M.BERTHOLLET, -We have here a learned and valuable memoir, which is after. ward augmented by two supplementary papers: but it would be useless to attempt an abridgement of it which would be adapte ed to the limits of our work; because such an abstract could not satisfy our chemical readers, while others would naturally complain of įts dryness and prolixity.

Chemical Reflections on the Use of the Oxides of Iron in dying Cotton. By M. CHAPTAL.- This active chemist here observes, first, that the affinity of cotton for oxide of iron is so great, that it immediately separates the particles of the latter which may be suspended in any solution, and that the solution becomes gradually transparent, in proportion as the cotton assumes the yellow colour of the oxide. This colour, however, although at first agreeable, is rendered coarse and ochraceous by exposure to the air, from the progressive oxidation of the metal, As the colour arising from oxide of iron is very fixed, and is not liable to alteration from air, water, alkaline lixivia, or soap, it has always been much esteemed by Dyers. These artists in general make a mystery of the acid which they use as the men. struum : but the acetous, sulphuric, nitric, or muriatic acids may be employed for this purpose ; although the acetous and other vegetable acids are in some measure preferable, because they do not injure the texture of the stuff, which frequently happens when the mineral acids are used.

The oxidation of iron appears to be equal in the various acid menstrua, since all of them produce the same shade of colour on the stuff which is dyed: if, therefore, the properties of the ferruginous salts be fully understood, so that certain inconveniencies may be prevented, any of the acid solutions can be employed in the process of dying.

After these preliminary remarks, M. CHAPTAL describes several modes of communicating buff, yiolet, and some other colours, to cotton, which appear to be very useful : but, for the particulars, we must necessarily refer to the original paper.

On refining Lead on a large Scale. By M. DUHAMEL.The author first remarks that the metallurgical process, (by

which silver is separated from lead,) called refining, or cuppellation, is well known. This operation is performed in a bason, or other vessel, made of burnt bones, or the ashes of vegetables which have been previously deprived of saline matter by washing. The great quantity of wood ashes, required for the construction of these vessels or cuppels, and the difficulty of procuring wood ashes, induced M. DUHAMEL to endeavour to find some more simple and less expensive means of forming these basons; and he shews that sand may be employed for this purpose in the large way, provided that the lead, instead of being so much vitrified as to be imbibed by the cuppel, be simply converted into litharge, which is to be progressively removed by bellows and other means, until the silver remains nearly in a state of purity. M. DUHAMEL is convinced that this mode of proceeding may be adopted with very great advantage.

Essay on the Analysis and Recomposition of the two fixed Alkalis, and of some of the Earths which are reputed to be simple or primitive. By M.M. Guyton and Desormes.— The contents of this paper appear to have been so satisfactorily refuted by M. Darracq, in a Memoir published in the Annales de Chimie *, (Tome 40, p. 171), that we deem it unnecessary to trouble our readers with the particulars of it.

Second Memoir on the Use of Mercurials in the Small-Pox. By M. DESESSARTZ. -- In the former paper on this subject, (see M. R. vol. xxxv. N. S. p. 531.) the author concluded that mercury, given in the small-pox before the attack, and in the course of the disease, when complicated either with the lues venerea or with herpetic eruptions, not only was not hurtful, but mitigated the usual severity of the small-pox. In the present memoir, he attempts to confirm his former conclusions by additional cases of small-pox supervening on the lues venerea and herpetic eruptions, ander the influence of mercury. In one of these cases, the mother and the infant at the breast were in a state of mercurial salivation when the small-pox superpened in the infant, who had this disease in a regular and mild manner. - The writer quotes the observations of Malouin, Poissonier, Rosenstein, Lowe, Roussel, Van Woenzel, Gouillart, Grassius, Boerahave, &c. to evince the power of mercury in mitigating the small-pox : but the preventive powers of this drug cannot be proved by evidence.

Third Memoir on the Utility of Mercurial Preparations in the Treatment of the Small-Pox. By the Same.-M. DESESSARTZ * Şce a subsequent Article in this Appendix, p. 524.5.

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here continues his account of cases, in order to shew the utility of mercurial preparations in the small-pox ;; and he explains his method of employing mercury as a preparation for inoculating, or for mitigating the natural small-pok.

His mercurial preparation consists of calomel, with double its weight of jalap, iris root, and sugar, triturated together. It is administered so as to purge daily, both before the invasion of the small-pox, and on its attack, to the time of complete suppuration.

The well-informed English Physician will perceive nothing new in the above memoirs ; and he will demur to the opinion that the treatment recommended operated by any specific action of mercury: deeming it more reasonable to impute the good effects produced, to the removal of irritating matter from the stomach and bowels by purging, -5

Memoir on the Changes which take place in the Organ's of Circulation in the Fætus, when it has begun to breathe. By M. SABATIER.-Instead of adopting the general idea that the blood passes from the right auricle to the left, and from the left to the right, this author thinks that all the blood of the vena cava inferior passes into the left auricle, and the blood of the vena cava superior into the right auricle; whence it would follow that, in the foetus, all the blood returns nearly as in the adult before it commences its course, and traverses the aorta. To explain why, after birth, the blood ceases to pass through the foramen ovale, from the right to the left side; and why the canalis arteriosus, and the umbilical arterits, are closed; is the object attempted in the present membir, by an observation which has escaped anatomists, viz. the structure of the aorta as it goes off from the left ventricle: but for this anatomical explanation, we must refer to the

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itself. Inquiries concerning the Cause of Umbilical Rupture at the Time of Birth. By PIERRE Lassus.-A hernia at the umbilicus, formed at birth, is a rare occurrence; and it is seldom curable, unless it be slight, and has been formed a short time before birth. If the tumor be small, and still covered with peritoneum, and with the aponeurosis which forms the linea alba, it is possible to make a radical cure, and no strangulation is to be apprehended : but it will often gradually reduce itself. The hernia is sometimes formed in the first month of pregnancy ; and the great size of the liver is supposed to be the chief cause of this affection.

NATURAL HISTORY. On a new Methodical Table of the Classes of Birds. By M. LACÉPÈDE.—This well-known and ingenious naturalist, have

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