degree of metallic fplendour. It is opaque, brittle, and lightr it foils the fingers, and, in its hardest ftate, can be cut with a knife. In a chemial view, it comes very near the plumbago.

It is in the green glimmer of the Saxons that M. Klaproth Has found his new metal the uranite, or, as he has fince called it more correctly, the uranium. This glimmer is yet little known; we find the best mineralogists will not admit it among the copper ores, and it must be referved for farther enquiry. The uranite we have not yet had an opportunity of deteribing more particularly; and, as it has not hitherto been taken into any fem, we fhall now mention what has been discovered by M. Klaproth, the only chemist whofe particular attention it has attracted.

What has been styled the pech blende was at one time inferted among the ores of copper, and M. Werner first showed that it was not properly a blende. He ftyled it therefore an ore of iron, by the name of ferrum ocraceum piceum; and he afterwards fuppofed it iron united to tungsten. Our author shows that neither opinion is correct. The pech blende, in mais, is of a blackish colour verging on the grey, having little brilliancy, breaking irregularly and concave in fome of its parts. It is perfectly opaque, fufficiently hard, and gives, by rituration, a black powder. Its fpecific gravity is 7.500. The other variety, which is found in veins, is of the colour of brown iron ore, or hæmatites, commonly accompanied by a yellowith or brownish earth, in which is a green fubitance crystallized in quare lamina: this fubftance was taken for green glimmer. The regulus was imperfectly fufed, and the colour appeared of dead filvery white, feemingly arifing from minute coherent globules. It is, from our author's experiments, to be confidered as a new metal, but they have not proceeded far enough to establish this polition It fecms from its intractibility to contain the phofphoric acid, and may at last prove an old metal in difguife. Our author has given three fpecies of it, uranites fulphuratus, mineralized by fulphur: this fpecies is what we firft defcribed, and is of a deep grey, mixed with galena; or more black, refembling charcoal: the fecond is the uranites ocraceus luteus; and the third the uranites crystallized in fquare lamina. In the fubfequent account, where M. Klaproth tells us that he has changed the name to uranium, he lays that when diffolved in the nitrous acid, he obtained very beau tiful cryftals, three-fourths of an inch long, and one-fourth of an inch large, in hexagonal laminæ, of a fine green colour, The green glimmer (argilla calcolitas) fuppofed by Bergman to be a copper ore, contains the uranium, and has only a very minute proportion of copper.

It was a bold decifion, when M. Romé de l'Ile confidered the jargon of Ceylon as a peculiar kind of ftone, from the peculi mity of its crystal, which is a tetraedial prifm terminated by two obtufe pyramids of a fimilar form, refting on ifofcules tri

angles.

angles. The accuracy of cryftallography was a little fufpected when M. Wiegieb extracted from it only the ufual primitive earths: M. Klaproth thinks, on the contrary, Romé de l'Ifle's opinion just, as it contains a large proportion (68.in 100) of a peculiar, at least an intractable earth. M. Wiegleb's crror, he fufpects, was owing to his powdering the jargon in a glaf: mortar. Befides the earth of Ceylon, it contains fome flint, and a very minute proportion of nichel.

As the defcription of mineral fubftances is not a generally pleafing fubject, we shall at prefent add but one other; it is a filvery feld fpath, called the fishes eye, found in the black mountains of Languedoc, defcribed by M. Dodun. Our author gives a very good defcription of this mountain, and of the fpar which is the object of his enquiries. From an lyfis he found it to contain nearly one half of flint, and almost as much argil, with above onc-fixth of calx of iron. The analysis of other chemists differs from his, and there is great reafon to fuppofe that in different fpo's the nature of this foffil is different. The fifles eye preferves its brilliancy in very great heat. M. Dodun has added a fupplement to his memoir, in which he defcribes this foffil according to the natural method of M. Wer

ner.

We fhall purfue our sketch with fome chemical accounts, which may appear more interefting. Of the more fplendid appearances of chemistry, phofphorifm, and the different properties of the phofphoric acid, form a very confiderable proportion; and this property is now found to be very extenfive, for many fubftances receive light, which they feem to throw off again in the dark, and we begin to be accustomed to light without heat. In fugar, this property is well known: and it has lately been difcovered in roten potatoes, and in vitriolated tartar. This light is, however, always to be distinguished from the electri cal fluid on one fide, and from fmall animals on the other; many of which on their motion throw out fome phofphorefcent partices. The phofphorifin of rotten potatoes, which was difcovered by accident in the barracks of the foldiers at Strafburgh, is not exempt from the fufpicion of animal origin. It may be at any time tried by cutting a potatoe of a yellowish colour, not fo wholly rotten as to lofe its farinaceous appearance. The phofphoric light of vitriolated tartar cannot be owing to either caufe. The appearances are related in a memoir of M. Giobert, read to the Royal Academy of Sciences on the 4th of January of last year. They occurred in the preparation of magnelia, after the earth was wholly feparated; the falt had accidentally crystallized in part, and, in the moment of decanting the liquor, the light being accidentally taken away, the bottom of the copper vellel was covered with phofphoric light, which, on disappearing, was renewed by the flightest motion of the cryitals, or dropping other cryftals into the velf 1. If a point was drawn along the furface of the cryftallized mafs,

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its

its traces were distinguished by a blue phofphorefcent light. The experiment fucceeded alfo in veffels of tin, of earth, of porcelane, of Durch deift, and of pewter. The furface of the veffel mutt be large, the evaporation not carried farther than will barely admit of crystallization; the cryftals mult fhoot in the cold, and the earth be entirely feparated. The water is abfolutely neceffary to the appearance. The folution of the falt, in any degree of concentration, is not at all phofphoric; nor does the light affect the nicest electrometer. Light is, as may be expected, eflential to the fuccefs of the operation, and the crystals, forined in the fun, are most phofphorefcent. Other vitriols, fea-falt, and alum, have not this property.

Photphoric air affords at times fome fingular phænomena. It feems to refemble hepatic air, in being the inflammable body combined with inflammable air. M. Gingembre found that it detonated with pure air, though this property is not common, and is loft when the phofporic air has ftood on water. It mixes quietly with common and pure airs, but with nitrous air a thick cloud is for ned, and probably the phofphorus precipitated. When nitrous air is admitted to phofphoric and pure airs, this phosphorus takes fire, and explodes with violence.

A lefs degree of detonation follows the mixture of regulus of antimony and charcoal, thrown into dephlogisticated marine acid air. Oyfter-hell lime inflames in it, probably from the admixture of fome phofphorus; and volatile alkali, added to this air, forms a fea of fire. Cinnabar of antimony, kermes mineral, golden fulphur of antimony, and regulus of antimony, of arfenic, bifmuth, nichel, cobalt, tin, lead, copper, and iron, inflame by being put only into a jar of this air without any

heat.

M. Sage has again noticed the fulminating power of the neutral, formed of dephogifticated marine acid and fixed alkali. It fulminates, however, with fo little friction, that the preparation of it, and its application inftead of falt-petre in the manufacture of gunpowder, are very dangerous. In this memoir, he gives a long account of manganefe and oxygenated marine acid, mixing many of his own peculiar opinions; but, at the fame time, defcribing the preparations with very confiderable accuracy.

We have received a curious application of the modern chemical theory of airs, from M. Girtanner, an author of no inconfiderable ability, who endeavours to prove that irritability is in proportion to the oxygen in the blood, and the contrary. His memoirs are extenfive: they contain many facts of importance, fo that we fhall give as concife an account of them as

we are able.

The firit memoir is an extract from a larger work. It con tains facts without proofs, and affertions without arguments: in the outline, our author approaches very near to Dr. Brown, and is, in fome refpects, as fingular and eccentric as that zealous

3

reformer.

reformer. M, Girtanner divides fibres, into the earthy fibre, that of the bones; the fentible fibre, the nerves; and the irritable or mufcular fibre. Every fibre he confiders as fimilarly organized, and differing only in the fubitance or the fluid which is connected with it. In this refpect, he seems to have fallen into a fundamental error; but, as he has referved his proofs, we must referve our objections, till we fee his future work. The mufcular and nervous fibre are reprefented as diftinct in their functions, and one may be confidered, in our author's opinion, as difeafed, while the other is found. Yet thefe two kinds of fibres are reprefented as mutually acting and reacting on each other; and thefe motions are faid to be the occafion of voluntary exertions of convulfion, and nervous dif eafes. The irritable fibre is found in every animal and plant; and, in Dr. Girtanner's opinion, is the fame in each, differing only in form according to its functions. Thus in the extre mities of animals and of plants, we find the strait fibre; in the inteftines of animals and the trachea of vegetables, the fpiral; and in the fphincters, the circular fibre.

The fluids of animals and plants are equally irritable with the folids, and their irritability is faid to contift in their coagulability, and to be fubject to the fame laws as the irritability of the folids. This our author adds, is a new difcovery, and the bafis of many brilliant truths. The degree of irritability varies; its proper ftate is called, in the language of Stahl, the tone of the fibre; the fecond is the state of accumulation produced by the abstraction of the ufual ftimuli,' which we fhould call too great irritability, and it is followed or attended by nervous debility, and the ftate of exhauftion,' produced by the action of a too powerful ftimulus. The tone confifts in a just balance between the excitability accumulated, and that which is deftroyed; the fate of accumulation in an excess of irritability, and of exhauftion, in its defect. A fibre, when its excitability is leffened by action, does not immediately recover it, and this is the reafon, in our author's opinion, why the heart does not immediately act on a return of the ftimulus of the blood, and other actions do not follow the stimu lus, except after fome interval. All these are, however, inftances taken from hollow mufcles, which it is now known, do not act from any chemical ftimulus, but from diftenfion. One proof of this is, that a glyfter of the mildeft kinds is as fuccesful, as one compofed of the most active materials, if the bulk be fufficient to fill the rectum.

The exhauftion of irritability by too great stimulus is a fact well-founded in the phyfiology and pathology of plants and animals, and feems to fhow that irritability really depends on a peculiar fluid, which appears to be communicated to the exbauited fibres from thofe adjacent. The application of this doctrine, that poifons, thofe utually diftinguished by the name of fedative poifons, kill by exhaufting the irritability, in confequence of too great ftimulus, is more fufpicious. The ftimulant

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poifans

poifons may have this effect, but the power of the others is cer tainly of a different and oppofite kind. The irritable fibres have, in our author's opinion, a differente apacity of irritability, in proportion to their distance from the heart; and one of these fibres, when affected by any ftimulus, foon affects the others. Thus he accounts for fympathy, independent of nerves; though if we understand him rightly, be confines fy mpathy to the connection between fibres equally diftant from the heart; but how will this explain the connection between the feet, or the ligaments of the joints and the ftomach?

Difeafes are confequently divided into thofe of accumulation and of exhauftion. All poifens, we have obferved, act by ex. hauftion, according to this fyftem; and the fluid alkali, our author fays, instead of curing the effects of the poison of the viper, will act exactly in the fame manner, if applied in the faine way. M. Girtanner next examines the effects of the habitual ftimuli, and the confequences of their increase. Heat, he fays, produces difeafes of exhaution; cold, thofe of accumulation. After cold the irritability is fo great, that a flight flimulus exhauts the excitability; limbs imprudently warmed mortify; the leaft motion fatigues. When the fimulus is properly and regularly applied, vegetation, as is teen in the arctic circle, is rapid; the circulation is carried on with vigour; and the whole flem is in the best flate. It is remarkable that fleeping animals come out in the fpring, when the weather is colder than that which drove them to their retreats; a circumstance accounted for by our author from the accumulation of irritabi lity. Another habitual fimulus is light; and here, we think, the fyftem fails, for excitability must be accumulated by the privation of light, but, in every inftance, it injures the health of a plant. Nourishment, another habitual ftimulus, is in part ufeful, we are told, to deprive the stomach of is accumulated irrritability. In this way the various fedatives act in presenting hunger; and, according to the fyftem of accumulated in itability, are explained the fatal effects of giving food too quickly to those who are almost famished. The circulation of the fluids is another ftimulus; and the blood, in paffing through the lungs, takes in vital air, which is imparted, in different organs, to the fibres, after having depofited its heat. When the circulation is more rapid the irritability increafes by the addition of vital air; but, at the fan e time, the excitabil ty is leffened. The modo of relieving fever is, therefore, to prevent a fupply of pure air, or to lefien the quantity of blood, and to check the too great irritability. The nervous ftimulus, that is volition or paffion, is alfo habitual. The depreffing patlions are only abftractions of fimulus, and occafion accumulated irritability; fo that joy after if is fatal, for the irritability is very rapidly exhausted by this powerful ftimulus. The abitraction of many of the habitual stimuli produces fcurvy,

Dr. Girtanner's fecond memoir is defigned to fhow, that the principle of irritability is the oxygen. During refpiration, he

obferves