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By information transmitted to the Board from their numerous correspondents in all parts of the country,it appears that vaccination is almost every where gaining ground, throughout the British dominions, though its progress is very different in different places; and it is found that the number of deaths from the small-pox is uniformly decreasing, in proportion as vaccination becomes more general, and the inoculation of the smallpox declines.

The disappearance of the small-pox from the island of Ceylon, was noticed in the Report of last year; and the Board has now the pleasure of stating, from sources of authentic and satisfactory in formation, that, in consequence of vac. eination, this dreadful disease has in no instance lately occurred in the island of Anglesey, in the populous city of Newcastle-upon-Tyne, in the town of Petworth, or in the adjoining district.

Through the different counties of Eng land, the practice of vaccination is becoming general, and the small-pox is gradually declining; and even in London, where the opposition to the new inoculation has been most violent, it is prevailing, and its salutary effects are becoming daily more evident. At present, by the best estimate we are able to make, it appears that nearly two-thirds of the children annually born in the metropolis, are vaccinated either by charitable institutions or private practitioners; and that the number of deaths by small-pox has proportionally decreased. Previous to the discovery of vaccination, the average number of deaths by small-pox within the bills of mortality, was 2,000 annually; whereas, in the last year, only 751 per sons have died of that disease, although the increase of population within the last ten years has been 133,139. The increase of population throughout Great Britain, in the same period of time, has been 1,609,000; and to these augmentations the practice of vaccination has probably much contributed.

The Reports from the Cow-pock In stitution in Dublin, are of the most favourable nature, and furnish sufficient reason to believe, that, since the introduction of the vaccine preventive, the mortality from small-pox has considerably declined in that city. The correspond. ence of the Institution affords satisfactory evidence of the progressive increase of vaccination throughout Ireland. In most of the principal towns of that kingdom, the poor have the advantage of

gratuitous inoculation with cow-pox, either at the hospitals, or at the houses of the physicians; and it is stated, that, among the higher ranks, vaccination is universally adopted.

The accounts from Scotland, particu larly those from the faculty at Glasgow, which have been transmitted to the Board, furnish evidence of the general and rapid increase of vaccination in the northern part of the island, and give the most satisfactory proofs of the success and efficacy of the practice.

Notwithstanding the incontrovertible evidence of the very great advantages of vaccination, it is much to be lamented that there are still some medical practitioners, though the number of them is comparatively small, who obstinately persist in disseminating by inoculation the contagion of the small-pox, and who strenuously encourage and support, especially among the lower orders of the people, the prejudices against the new practice; rumors are industriously spread abroad, of deforming and loathsome diseases produced by this practice; and nu merous mis-statements of cases are published, of the occurrence of small-pox after vaccination. That, in some instances, the small-pox has affected per sons who have been most carefully vac cinated, is sufficiently established; nor ought we to be surprised at this, when we consider that the inoculation for the small-pox sometimes fails, and that several cases may be produced, in which per sons have been affected with the natural disease more than once in the course of life. The number of instances of small pox after vaccination, however, is very small; and we may fairly presume, that in proportion as improvements are made in the practice, such occurrences will be still more rare.

The Board have infinite satisfaction in stating the two following important and decisive facts in proof of the efficacy and safety of vaccination, viz. that, in the cases which bave come to their knowledge, the small-pox, after vaccination, with a very few exceptions, has been a mild disease; and that, out of the many hundred thousand persons vaccinated, not a single well-authenticated instance has been communicated to them, of the occurrence of a fatal small-pox after vaccination.

They cannot conclude their Report, without adverting to the mischiefs which are daily arising from the diffusion of the fatal contagion of small-pox in the com

munity,

munity, in consequence of variolous ino. culation, among the lower classes of the people, which constantly keeps up the contagion, and, where it saves a single life, exposes numbers to a most dangerous disease. It is greatly to be wished that this evil could be checked, by such measures as government in its wisdom might judge proper to frame, in order to prevent the spreading of the small-pox, and thus keeping up a continual source of infection in the heart of the metropolis.

IMPERIAL INSTITUTE OF FRANCE. Inquiries of Messrs. Malus and ARAGO relative to Light.

A direct ray of light, as is well known, possesses the property of dividing itself into two distinct bundles in its passage through a rhomboid of Iceland spar, whatever in other respects may be its position in relation to the principal section of the rhomboid.

If we subject the light of which one of these bundles is composed to the action of a second rhomboid, we find that it differs essentially from the direct light, since, in certain positions of the principal section of the second crystal, it no longer undergoes double refraction: for the discovery of this beautiful property we are indebted to Huygens,

When endeavouring to account for this experiment, Newton remarks, in one of the questions which he has placed at the end of his Treatise on Optics, that it is necessary to admit that the mole cules of which the luminous rays are composed must have sides endowed with different properties: these sides, which some authors have designated by the appellation of poles, are diametrically opposite to each other, and in two directions respectively rectangular.

This being granted, in a ray of ordinary light, the poles of the molecules will not affect any particular position, and will be uniformly directed towards all the points of the space; whereas a polarized ray will be composed of mole cules, the similar poles of which will have the same situation: this last ray will be distinguished from a ray of direct light, in so far as the latter is always divided into two fasciculi in its passage through a rhomboid of carbonate of lime; while the polarized ray experiences only a single refraction in some particular positions of the principal section of the crystal to which we present it.

The polarized rays differ from the rays

of direct light by several other properties which were unknown to Huygens and to Newton, and the discovery of which is owing to M. Malus. If we suppose, in fact, that, after having disposed vertically the principal section of a rhomboid of carbonate of lime, we receive the two fasciculi which proceed from them on the surface of smooth water, and under an angle of 52° 45′, we shall remark that the common fasciculus acts like the direct ray; since it abandons to the partial reflection a part of its molecules: as to the extraordinary fasciculus, it pene trates the liquid quite through. If we Suppose, on the contrary, that the prin cipal section of the rhomboid is perpendicular to the plane of incidence, the extraordinary ray undergoes the partial reflection, and the ordinary ray pene trates the liquid entirely.

When we examine, by the help of a rhomboid of calcareous spar, the light which is reflected on the surface of the water, and under an angle of 52° 45',

we see that it has all the characters of

one of the fasciculi produced by the double refraction of a crystal, for it no longer constantly separates into two fas. ciculi: in this experiment, which is in some measure the converse of that which we have first referred to, the plane of reflection performs the office of the principal section of the first rhomboid. We have only explained these results (which are detailed at great length in the elegant work by M. Malus, to which the class decreed the prize of mathematics for 1810) in order to indicate the point from which the members of the class set out, who were occupied with this object in 1811.

We have hitherto only alluded to the modifications which the luminous rays undergo in their reflection. Is the light transmitted by diaphanous bodies, even modified in certain circumstances which we are about to mention?

If we place two object-glasses, one above the other, there are formed, as we all know, some colored rings, of which the point of contact is the common centre: these rings are perceived either by the aid of reflected or of transmitted light. When the angle of the rays transmitted with the surface of the object-glass is about 320, they are polarized, since in certain positions of the principal section of a crystal of Icelandic spar, we see only a single image of rings. Now, it is a very remarkable circumstance in this experiment, that the mo

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On the 11th of March, M. Malus announced to the Class, that, on subjecting, at various times, the light which the glasses transmit under an angle of 35° 25', he had ascertained that this light is com posed of a certain quantity of rays polarized in a direction contrary to the reflect ed rays, and of another portion of rays not modified, which preserve the proper ties of the direct light: this last portion diminishes at each new transmission of the fasciculus; so that, if we pass through a pile of parallel glasses, the portion of light transmitted is entirely polarized in one direction, while the rays successively reflected are polarized in a contrary direction. M. Malus concludes from this, that at all times, when by any contrivance we produce a ray polarized in one direction, we necessarily obtain a ray polarized in a direction diametrically opposite, and that these rays follow different routes.

The observation of M. Arago, which we have recently mention ed, forms the only exception to this ge neral rule, since the rings reflected and transmitted are polarized in the same

manner.

M. Arago had long ago ascertained that diaphanous and opake bodies modify the light which they reflect: the me tallic bodies alone seemed to him to impress no new property. It is true that opticians were well aware that there was a slight difference between the intensity of the two images formed by a rhomboid, by the help of rays reflected by a metallic plane: but this isolated fact could teach MONTHLY MAG. No. 232.

us nothing relative to the particular mode of action of the metallic bodies and of light. But, in a memoir read to the Institute on the 27th of May, 1811, M. Malus has shown, by experiments made on rays already polarized, and by the help of a method of which it would be difficult to give a clear idea in an extract, that the light reflected by the metals contains at once rays polarized in two directions, so that, in its decomposition by a crystal of carbonate of lime, it acts like the ordinary light.

Hence it results, that all the bodies in nature polarize the light under determinate angles, and that sometimes among these angles the rays receive this modification in a very incomplete manner.

ROYAL SOCIETY.

Mr. Brodie has extended his experi ments on poisons to those of the mineral kingdom, and his valuable paper was read to the Royal Society on the 27th of February last.

Since (says he) I had the honor of communicating to the Royal Society, some observations on the action of certain poi sons on the animal system, I have been engaged in the further prosecution of this inquiry. Besides some additional experiments on vegetable poisons, I have instituted several with a view to explain the effects of some of the more powerful poisons of the mineral kingdom. The former correspond in their results so nearly with those which are already before the public, that, in the present communication, I shall confine myself to those which appear to me to be of some importance, as they more particularly confirm my former conclusions respecting the recovery of animals apparently dead, where the cause of death operates exclusively on the nervous system. In my experiments on mineral poisons, I have found some circumstances wherein their effects differ from those of vegetable poisons, and of these I shall give a more particular account.

Experiments with the Woorara.-In a former experiment, I succeeded in recovering an animal, which was apparently dead, from the influence of the essential oil of bitter almonds, by continu ing respiration artificially until the impression of the poison upon the brain had ceased; but a similar experiment on an animal under the influence of the woorara was not attended with the same success,

On the Effects of Arsenic.-When an animal is killed by arsenic taken interIi

nally,

nally, the stomach is found bearing marks of inflammation; and it is a very general opinion, 1, that this inflammation is the cause of death: 2, that it is the consequence of the actual contact of the arsenic with the internal coat of the stomach. But in several cases I have found the inflammation of the stomach so slight, that on a superficial examination it might have been easily overlooked; and in most of my experiments with this poison, death has taken place in too short a time for it to be considered as the result of inflammation: and hence we may conclude, that the first of these opinions is incorrect; at least as a general proposition.

Many circumstances conspire to show that the second of these opinions also is unfounded.

In whatever way the poison is administered, the inflammation is confined to the stomach and intestines; I have never seen any appearance of it in the pharynx or esophagus.

The symptoms produced by arsenic may be referred to the influence of the poison on the nervous system, the heart, and the alimentary canal. As of these the two former only are concerned in those functions, which are directly necessary to life, and as the alimentary canal is often affected only in a slight degree, we must consider the affection of the heart and nervous system as being the immediate cause of death.

is some variety in the symptoms produced even in individual animals of the same species.

In animals killed by arsenic, the blood is usually found fluid in the heart and vessels after death; but, otherwise, all the morbid appearances met with on dissection, are confined to the stomach and intestines. As this is the case, and as the affection of these organs occasions remarkable symptoms, it may be right to mention the result of my observations on this subject.

Experiments with the Muriate of Ba rytes.-When barytes is taken into the stomach, or applied to a wound, it is capable of destroying life; but, when in its uncombined state, its action is very slow. The muriate of barytes, which is much more soluble than the pure earth, is (probably on this account) a much more active poison.

On the Effects of the Emetic Tartar.— The effects of the emetic tartar so much resemble those of arsenic and of muriate of barytes in essential circumstances, that it would be needless to enter into a detail of the individual experiments made with this poison.

On the Effects of the Corrosive Sublimate. When this poison is taken inter nally in very small and repeated doses, it is absorbed into the circulation, and produces on the system those peculiar effects which are produced by other preparations of mercury. If it passes into In every experiment which I have made the circulation in larger quantity, it exwith arsenic, there were evident marks cites inflammation of some part of the of the influence of the poison on all the alimentary canal, the termination of organs which have been mentioned; but which may vary accordingly, as it exists they were not in all cases affected in the in a greater or less degree. When taken same relative degree. In the dog, the in a larger quantity still, it occasions affection of the heart appeared to predo- death in a very short space of time. I minate over that of the brain, and on ex- had found, that, if applied to a wounded amining the thorax, immediately after surface, it produced a slough of the part death, this organ was found to have to which it was applied, without occaceased acting and in a distended state. sioning any affection of the general sysIn the rabbit, the affection of the brain tein. This led me to conclude, that the appeared to predominate over that of the effects of it, taken internally and in a heart, and the latter was usually found large quantity, depended on its local acacting slowly and feebly, after the function on the stomach, and were not con tions of the brain had entirely ceased, nected with the absorption of it into the In the rabbit, the effects of the arsenic circulation. on the stomach and intestines, were usually less than in carnivorous aniinals.

The action of arsenic on the system is less simple than that of the majority of vegetable poisons. As it acts on different organs, it occasions different orders of symptoms; and, as the affection of one of another organ predominates, so there

.

That a sudden and violent injury of the stomach should be capable of thus speedily proving fatal, is not surprising, when we consider the powerful sympathy between it and the organs, on which life more immediately depends, and the existence of which many circumstances in disease daily demonstrate to us.

The facts which have been stated, appear

pear to lead to the following conclusions respecting the action of the mineral poi. sons which were employed in the foregoing experiments.

1. Arsenic, the emetic tartar, and the muriate of barytes, do not produce their deleterious effects until they have passed into the circulation.

2. All of these poisons occasion disorder of the functions of the heart, brain, and alimentary canal; but they do not all affect these organs in the same relative degree.

3. Arsenic operates on the alimentary canal in a greater degree than either the einetic tartar, or the muriate of barytes. The heart is affected more by arsenic than by the emetic tartar, and more

by this last than by the muriate of ba rytes.

4. The corrosive sublimate, when taken internally in large quantity, occasions death by acting chemically on the mucous membrane of the stomach, so as to destroy its texture; the organs more immediately necessary to life being affected in consequence of their sympathy with the stomach.

In making the comparison between them, we observe that the effects of mineral are less simple than those of the generality of vegetable poisons; and, when once an auiinal is affected by the former, there is much less chance of his recovery than when he is affected by the latter.

PATENTS LATELY ENROLLED.

Communications of Specifications and Accounts of New Patents, are earnestly solicited, and will always command carly Notice.

MR. LAWRENCE DRAKE'S, (CLOAK LANE, LONDON,) for a Method of preparing the various Sorts of Isinglass from River and Marine Fish.

THE

THE fish, according to the description given of this invention, must be slit or cut down the middle: the intestines and sounds taken out, and well washed and cleansed from all impurities. The head is then to be slit open, and the white skin of the palate, as well as the white skin on each side of the head, cut and stripped off, scraped and entirely cleansed of the fleshy parts. The sounds must be freed from all fat and animal substance, and cut through the middle, after the inside skin has been taken off. The maw is then to be cut or slit open, and all fleshy parts well scraped off, that the pure skin may remain. With the ovarium the same process is to be observed after the roe part is thoroughly cleansed. The white skin from the gilis down to the navel on each side of the belly part is to be cut or stripped off, and well cleansed and scraped. The lower membranes of the flat fish are to undergo a similar operation. When these parts are well washed in cold water they are then to be hung up to dry, but, while they remain moist, they are to be dipped in warin water, but not boiling hot, in order to draw out the fishy taste and smell. They are to be taken quickly out, and then to be formed into long staple or short staple, and book isinglass.

The thin skins will, of course, require less dipping than those of a thicker substance. After this process they must be dried, either in a stove or in the sun, and when so dry they are fit for use. "The staples," says the patentee, "are merely fanciful, although an artful idea hitherto used to avoid detection of the original consistency. To make the cake isinglass, the cuttings arising in the manufacture of staples are warmed in a pan over a slow fire until they combine, but great care must be taken that they do not burn."

MR. S. BENTHAM'S, (HAMPSTEAD, MIDDLESEX,) for a new Mode of exclu ding Water of the Sea, of Rivers, or of Lakes, during the execution of underwater Works of Masonry; or for the Security of Foundations applicable to the Construction of Sea-Walls, Wharfs, Piers, &c.

The method employed by the patentee for excluding the water, whether temporarily or permanently, for the purposes above referred to, is by means of a dam, constructed according to the manner de scribed in the specification, the principles of which will now be given.

The dam is to be made either in one piece of sufficient extent and suitable form to enclose the whole of the spot from which the water is to be excluded; or it is formed in several separate pieces, but in both cases in such manner as that Ii 2 the

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