longer enumerated as a British genus of plants. The Braffica muralis and Menenfis of Hudíon, are returned to the genus Sifymbrium; as Cardamine petrea is to Arabis. In the fame manner, the Hedypnois hieracoides, tectorum, and biennis of Hudfon, are returned to the Linnæan genera from which that botanist had removed them, namely, Pieris and Crepis. In the clafs Cryptogamia, the removals are ftill more numerous.

We have thus related the principal improvements which Dr Smith has introduced into the British Flora. A comparison of this work with fimilar ones, will fhew the most careless obferver, the great fuperiority it poffefes over them. The species are more accurately determined, and, in many cafés, referred to more proper genera. The fynonyms appear to have been examined with great care; and Dr Smith profeffes to have quoted none, except fuch as he had himself afcertained to be right. If to thefe we add the complete defcription given of every fpecies, the botanist will eafily conceive the highly finished state in which the work is given to the public. We have, therefore, no doubt but that Dr Smith will receive from all quarters, the praise to which he is fo justly entitled.

ART. VIII. Memoires de l'Academie des Sciences de Turin. An

née 1792 à 1800. Tom. VI. 2 Parties. pp. 600. 4to. Turin, 1801-2. De l'Imprimerie Nationale.

THIS volume contains many interefting and original productions

of the various learned Italians who belong to the Turin Academy. The papers which struck us as peculiarly worthy of attention, belong to the chemical, mathematical, and electrical departments of fcience. In each of thefe claffes, we find much to admire; and after fhortly noticing the fubjects of thefe tracts, we fhall proceed to lay before our readers a more detailed account of their contents, beginning with the chemical papers.

I. The chemical papers which principally deferve attention, are three- On the phosphoric light of certain ftones rubbed with a feather or a brafs pin'- Examination of hydrogenous gas after it had been kept many years,' both by Count Morozzo; and a tract upon

In one inftance, however, we have found an erroneous reference, viz. in p. 280, Kali fpinofum cochleatum, Raii Syn. 107; this ought to be 159. In Prunus inftitia, the fynonyms of Hudfon are omitted; in the first edition, it bore the fame name; but in the fecond, it was joined with P. domeftica, under the name of P. communis.

upon the combuftion of fulphur and the metals, by the Chevaliers St Real and Maistre.

II. The mathematical papers are of great ingenuity, and their fubjects very important- On the refolution of numerical equations of all degrees' On a problem of difficult analyfis, (viz. to defcribe the greateft poffible ellipfoid in a papezioid or irregu lar folid), both by the Abbé Calufo- On the refolution of equations of all orders,' by the Abbé Franchini- On the divifion of circular arcs,' by M. Michelotti-and An effay on the problem, An integral number being given for a fide of a right-angled triangle, to find all the pairs of integral numbers which form the other two fides,' by the Pere Saorgio.

III. The electrical papers are likewife valuable On the law of Volta,' by Dr Canali- Solution of fome questions in electricity,' by the Abbé Eandi- On the utility of conductors,' by Abbe Vafalli On the muscular attractions produced by animal electricity,' by Meffrs Julii and Roffi.

I. We begin with the first of thefe divifions, referving the other two for a future opportunity.

Of the Phofphoric Light which fome Stones give when rubbed with a Feather or a Brafs Pin, and particularly of the Phosphoresrence of the Tremolite and the Cyanite, with fome Obfervations on the Pofitive and Negative Electricity of different Stones. By the Count de Morozzo.

After reciting the facts formerly obferved on this fubject, with which our readers are fufficiently acquainted, Count Morozzo proceeds to detail fome circumftances which prefented themselves in the course of his experiments upon thefe curious appearances. Thefe experiments were chiefly made with a very delicate electrometer, invented and conftructed by the Abbé Vafalli, defcribed in the last volume of the Turin Memoires, and preferred by Count Morozzo to every other.

With this inftrument, good tremolite crystals gave, when rubbed, figns of confiderable pofitive electricity, as did alfo the Dolomie; but Cyanite Blende and Cadmie, though very Juminous, gave no marks whatever of electrifation. In this manner, our author was driven from his first opinion, that the phofphorescence of ftones is caufed by electricity; and he continued his trials, in order to difcover the true caufe. He found that marbles, and all calcareous fpars, when rendered luminous, gave proofs of negative electricity; that the barytic and gypfeous and felenitic fpars gave marks of pofitive electricity, as alfo the Bologna ftone; and that the fluoric fpars gave marks of neither the

one

one nor the other kind. He infers that the fpars containing carbonic acid contain negative electricity; while thofe which confift in part of fulphuric acid contain pofitive electricity. He confirmed this idea, by examining metallic ores, and finding pofitive electricity in proportion as the acid which neutralized the bafes was fulphuric; and negative electricity in proportion as that acid was carbonic. As a farther teft of his doctrine, he calcined barytic fpar and gypfum: the former, being deprived of its acid, gave negative instead of pofitive electricity; the latter, when deprived of its acid, gave neither. Our author adds, that thefe experiments are extremely delicate, and often fail, or give equivocal or contradictory refults. This he afcribes partly to the difficulty of finding fubftances perfectly homogeneous, partly to variations in the atmosphere, temperature, and manner of manipulating. But, in general, he thinks his experiments fufficiently consistent to authorise the inference, that there fubfifts fome connexion between carbonic acid and negative electricity; between fulphuric acid and, pofitive electricity. He concludes by noticing the experiments of le celebre Anglois M. John-read,' (meaning Mr John Read), with his doubler of electricity, and pointing out their coincidence with his own. This is remarkable in three points: first, that gentleman found, that atmospherical air, in a state of purity, is always pofitive; fecondly, that when corrupted by vegetable or animal putrefaction, it is negative; and, laftly, that refpiration in a clofe chamber renders the electricity of its atmosphere negative, when before it was pofitive. We extract the concluding fentence of this neat and interesting little tract, as a fpecimen of modefty not too common among philofophers, even among those of France and Italy.

Ce n'eft qu'un aperçu que je prefente à l'Academie. Ces experiences ont befoin d'etre beaucoup diverfifiées, et recevront par des mains plus habiles le degré de perfection que l'on peut defirer.' Part I.

P. 149.

The light given out by ftones, &c. may thus be thought by many to be an electrical phenomenon; and it may be fuppofed that this paper belongs rather to the laft of the claffes into which we have divided thefe memoirs. But, befides that the experiments of Count Morozzo do not by any means warrant fuch an inference, we have thought it proper to place his fpeculations in the prefent article, becaufe they refer directly, in our opinion, to a fubject which prefents important obftacles to the new chemical fyftem; and, in this particular, refemble both the other memoirs of which this clafs is compofed.

Phofphorefcence, in general, is by no means ranked among the proceffes of combustion, by the French system of chemistry. The

light,

93

light, unaccompanied by any fenfible heat, which certain ftones give out after expofure to the fun, or any very luminous body, and the inferior degree of radiation which is perceived in almost all bodies, whether inflammable or not, when placed in broad daylight, and suddenly transferred into a dark place, (fee Beccaria's experiments); these phenomena are commonly referred to the clafs of optical appearances, and are not fuppofed to have any connexion with inflammation. It deferves, however, to be remarked, that though the application of heat in all these proceffes greatly affifts the developement of light, ftill they refemble each other, and differ from ordinary cafes of irradiation in these two material particulars, that they are carried on without injury to the body, and fail if the body has not immediately before been exposed to the light.

But there is a clafs of phenomena which resemble more nearly the common appearances of combuftion, and which neverthelefs ought not, according to the French theory, to be ranked among thofe proceffes. We allude to the permanent phofphorefcence of certain fubftances in all circumftances, yet unaccompanied by any thing like oxygenation. Of this defeription, we fhall at prefent give only one inftance, but that a very remarkable one, and one which has not hitherto been examined with the attention it deferves. We allude to the infects commonly known by the name of fire-flies, and abounding in the fouth of Europe. They refemble, in their fize and external appearance, fome flies known in the north their fhape is oblong; their wings are covered with an outward fhell, like infects of the beetle tribe; the head is red, with a black spot in the centre. perch or creep, nothing is obfervable; but as often as they rife to In the dark, when they fly, a bright light is perceived. This is not conftant during their flight, but recurs every other inftant, as if it were difclofed by the opening of their wings at each fucceffive expanfion. When laid upon their back, they give out this light conftantly, and have much difficulty in turning themselves. The light, when thus examined, is a clear, phosphorefcent or lambent flame, of a green or light blue, inclining to yellow. It is very confiderable even in one fly; and the light of three or four is fufficient to render small ob jects around quite vifible. It is apparent in twilight. When thefe infects are examined by daylight, their bellies are perceived to be diftinctly divided about the middle, by a line paffing across the body. The under part is of a bright yellow, refembling in colour, fmoothnefs, and in every particular, a bit of fine clean ftraw: the rest of the belly is quite black; the yellow part alone is luminous. When the fly is dead, the luminous appearance still continues for two or three days. If the yellow part be cut off, it

thines as brightly as before; and if rubbed between the fingers, a luminous greafy matter, like the bowels, oozes out, tinging the fingers, wherever it touches, with the fame kind of lambent flame. This friction fpeedily terminates the phenomenon, apparently by exhaufting the supply of luminous matter. Air is by no means neceffary, or at all conducive to this procefs of phofphorefcence: on the contrary, under water, or other liquids, the Aies fhine as much as in the air.

Here, then, we have an animal procefs, at first fight refembling the flow combuftion of the blood in the lungs, rendered visible by the extrication of light. We find, however, that ne Oxygenation whatever attends it. In what manner, then, are we to draw the line between fuch phenomena ? This is not a cafe which can be explained by faying that light is absorbed, and then given out; for if the animal is kept alive for months in a dark place, the luminous appearance continues; and if it dies, that appearance furvives but a fhort time. Something is evidently fecreted, which burns or radiates with a lambent flame, and which does not owe this luminous quality to any previous contact with light. The flame is kept up without air exactly as well as with it. No oxygenation can therefore be fufpected. But no perceptible heat is evolved. Neither is any perceptible heat, or any perceptible light evolved in the firft ftages of combustion and oxygenation; yet the new theory never fails to fuppofe fuch an evolution of both; only adding, that it is fo flow as to escape the fenfes. Here, much light is given out; confequently, the process resembles combuftion much more than many cafes in which it is admitted to take place. In fact, it refembles combustion exactly as much as the first stages of common phofphoric inflammation. How fuch phenomena are to be feverally arranged and denominated in the theory of oxygenation, we are at a lofs to difcover. We fhall return to the same train of speculation, after analyfing the following papers.

Examination of Hydrogen Gas, which had been kept twelve years in a Bottle. By the fame Author.

Count Morozzo having been among the first to verify the celebrated difcovery of our countryman Mr Cavendish, happened to leave a pint bottle of hydrogen gas well fealed, with three inches of water under it, in his laboratory, from the month of February 1785, and to find it there in July 1797. He immediately tried fome fimple experiments, to examine the changes which it had undergone.

On opening the bottle under water, an abforption of two inches took place. It burnt exactly like common hydrogen gas. A fmall animal introduced into the bottle was feized with convul

fions,