union of a particle of each of the salts which enters as a constituent. Thus tartrate of potash and soda, or Rochelle salt, is composed of a particle of tartrate of potash united to a particle of tartrate of soda..

In the same way the metalline salts admit of analysis. They are usually composed of a particle of oxide united to a particle of acid. But to enter into particular details would oblige us to extend this article too far.

Such is a short sketch of Mr Dalton's most curious and important theory. It applies to all the compounds which have been analysed, especially to the salts, with such uncommon precision, that it is impossible for the most sceptical chemist, who takes the trouble to examine the subject with sufficient care, to refuse his assent to it. For further details respecting this theory, we refer the reader to Mr Dalton's New System of Chemical Philosophy, two volumes of which have been published; or to the third volume of Dr Thomson's System of Chemistry, 3d or 4th editions, where the subject is stated at considerable length.

13. Some additions have been re

cently made to our knowledge of animal substances, and of some of the animal functions, which deserve to be noticed. Mr William Brande has analysed a considerable number of urinary calculi, which are deposited in the Hunterian Museum in London, and has corrected some errors of preceding experimenters, and contributed some additional facts of his own. Preceding experimenters had detected a considerable number of substances in urinary calculi; the principal of which are uric acid, phosphate of lime, phosphate of magne sia and ammonia, oxalate of lime.

Fourcroy and Vauquelin had announced also urate of ammonia as a pretty common constituent; but Mr Brande has shewn that they were misled, partly by the urea, and partly by other alkaline salts, with which the uric acid was mixed. Urate of ammonia, it would appear from his experiments, is never found in urinary calculi.

The calculi formed in the kidney are usually composed of uric acid; though, when they lodge in that organ, they are sometimes coated over with the phosphates. Calculi composed of oxalate of lime are much rarer than any of the other species.

Mr Brande has shewn that the me dicines usually prescribed do not act as solvents, but often produce an additional deposite of calculous matter; the alkalies diminish the proportion of uric acid in urine; but they tend to increase the deposite of the phos, phates. Acids, on the other hand, promote the depositions of uric acid.

14. The phenomena of respiration, have attracted the particular attention of chemists, ever since the discoveries in pneumatic chemistry enabled them to ascertain the changes produ ced upon the air by drawing it into the lungs. Priestley, Goodwin, Menzies, Lavoisier, and Davy distinguished themselves particularly in these inquiries. It was ascertained that a portion of the oxygen of the air drawn in disappeared, and that a quantity of carbonic acid gas was found in its place; but doubts were entertained whether the bulk of the air inhaled was diminished, whether the azote which it contained was diminished, and what was the proportion of the carbonic acid formed to the. oxygen withdrawn. A very accurate set of experiments has been made by Messrs Allen and Pepys to elucidate

these particulars. The apparatus used was simple and ingenious, and every precaution was taken to ensure accuracy. The following may be considered as results established by these experiments.

The bulk of the air is not altered by respiration; the azote is not altered, but remains invariably the

same.

The carbonic acid formed is just equal in bulk to the oxygen which has disappeared. The air drawn into the lungs comes out loaded with about nine per cent. of carbonic acid gas. The quantity of this gas given out by a middle-sized man is 302 cubic inches in eleven minutes, which amounts to rather more than eleven ounces troy of carbon in 24 hours. When oxygen gas is breathed, a portion of it is replaced by azotic gas. This singular result cannot be accounted for in the present state of our knowledge. It is possible that it may have made its way into the oxygen by some unknown means through the body. When a mixture of hydrogen gas and oxygen gas in the same proportion as common air is breathed, the animal exhibits no symptoms of uneasiness, but always falls asleep. It would appear, therefore, that hydrogen produces a soporific effect when it comes in contact with the lungs. The experiment was made upon a Guinea pig.

Such are the most material discoveries in chemistry that have been made during the period to which our history extends. We deem it unnecessary to collect the insulated facts which have been added to different departments of the science, because it would be impossible to render them intelligible, without entering into much greater details than are consistent with their importance.

II. The investigation of the ana

tomy and physiology of plants was begun about 150 years ago by Grew and Malpighi; and since their time, many eminent philosophers have devoted their attention to this delightful study. Dr Hailes and Mr DuHamel particularly distinguished themselves by their discoveries. The most successful cultivator of this study at present in Britain is Mr Knight. His discoveries have been numerous and important, and he has prosecuted the subject for more than a dozen of years with much zeal and assiduity. One of his dissertations published within the period of our history claims our notice.

It is well known that the sap of plants is absorbed by the roots, and that it moves upwards from these or gans to the leaves, where it is digested and converted into the peculiar juices of plants. In trees, it had been ascer tained that the sap moves through the alburnum to the leaves; and large vessels, called tracheas by Grew and Malpighi, and alburnous vessels by Mr Knight, were conceived to be the vessels through which the sap passed. But a set of experiments, recently made by Mr Knight, have rendered this opinion very doubtful, if they have not altogether overturned it. These vessels are always full of air, except during the season when trees bleed. Though they be completely cut through, the sap still continues to find its way to the extremity of the branch, and the branch continues to live. Hence Mr Knight concludes, that the sap moves not through the alburnous vessels, but through the cellular substance of the alburnum. The alburnous vessels he considers partly as reservoirs for the sap, and partly as intended to increase the strength and lightness of the plant, on the same principle as the bones of animals are hollow. The strongest

⚫bjection to this opinion is, the force with which the sap issues out at the bleeding season; a force, as Dr Hailes found, able to overcome a column of mercury 34 inches high. Now it is difficult to conceive how it could move with such force through the cellular substance of the alburnum, unless that substance were precisely similar to a vessel, and had the property of contracting.

III. The Linnæan society still continue their useful labours. The ninth volume of their Transactions, published during the period to which our history extends, contains a great number of valuable dissertations, both in the departments of botany and zoology. The botanical papers, as usual, relate, with a few exceptions, to foreign plants, hence they cannot well be abridged. We shall notice some of the most striking novelties in the volume.

The mosses, within these few years, have undergone a great change in their botanical arrangement. A great number of new genera have been invented, and the old genera, especially the brium, hypnum, and mnium, have been subdivided. These subdivisions must be admitted to be great improvements. They simplify the characters, and, by diminishing the number of species belonging to each genus, diminish the labour of finding the botanical name of every particular moss. Dr Smith has added a new genus to the number, to which he has given the name of Hookeria, in honour of Mr Hooker of Norwich. The characters of this new genus are the following:

The capsule is ovate, and finely reticulated, from a scaly, lateral perechetium. The peristomium has sixteen teeth, both internally and externally, and internally it is membrana

ceous. The calyptra is reticulated and entire.

There are ten species described, all of them foreign, except one, formerly called hypnum lucens, which is a native of Britain; the rest are chiefly from New Zealand and New Holland.

The genus lichen constitutes one of the most difficult and interesting among the cryptogameous plants. It is exceedingly numerous; no fewer than 360 species, natives of Britain, having been already described. Acharius has lately published a most interesting work upon these plants. He has subdivided them into a variety of new genera, which greatly facili tates their investigation, and has very much improved the method of describing these plants. His new division deserves to be adopted. Mr Dawson Turner, who has distinguished himself so much in the description of cryptogameous plants, has published an account of eight new British lichens, accompanied by very accurate engravings. They are all na. tives of the south of England, and were all first observed by Mr Burrer. Some of them are new species.

One of the most difficult genera of the syngenesia class of plants is the hieracium. Different species of it, ranked among British plants, have ne. ver been seen by any living author growing native in our island. The hieracium dubium, and auricula may be mentioned as examples. Dr Smith has published a historical detail of all the facts known concerning these two species, which are arranged among British plants on the sole authority of Hudson. The hieracium murorum of Linnæus is the variety B of the Flora Britannica. What has hitherto been described as the hieracium sylvaticum was placed among the

British plants on the authority of Ray, who mistook a variety of the cinerarea integrifolia for a hieracium. A new species of hieracium, the cerinthoides, has been found in the Highlands of Scotland by Mr Don. Various additions have beeen made to zoology, both British and foreign, the most remarkable of which we shall here notice. It will not be expected, however, that we should notice the different systematic works which have appeared in different countries during the period to which our history extends these must unavoidably be in a great measure compilations.

Mr Kirby, who had already distinguished himself by several valuable papers on insects, has published a description of a new genus of insects, to which the name of Apion has been given. He has described 61 species; most, though not all, of which are natives of Britain. Several of them are quite new. Most of these insects had been previously arranged under the genus curculio of Linnæus, or the attelabus of Fabricius. Mr Kirby has shewn that they possess a wellmarked generic character.

Mr Marcham, well known for his valuable writings on insects, has published an account of a new genus of insects from New Holland, to which he has given the name of Notoclea. He has described and given figures of 20 species. These insects, however, are not absolutely new. They are described in Latreille's Genera Crustaceorum,et Insectorum, published at Paris in 1807, under the name of Coccinalloides.

Colonel Montagu, one of the most distinguished and indefatigable of the British zoological writers, and well known by his ornithological dictionary and other valuable works, has made several important additions to

the stock of British animals. We shall mention the principal.

The cancer or crab genus comprehends a considerable number of species. Mr Montagu has described the following, most of them not previously known to occur upon our shores. They were chiefly found on the coast of Devonshire. Cancer floridus, tu mefactus, denticulatus, astocus subterraneus, astocus stellatus, astocus multipes, astocus gibbosus, gammarus locusta, gammarus pulex, gammarus saltator, gammarus littoreus, gam. marus grossimanus, gammarus talpa, gammarus rubricatus, gammarus fal catus; in all 15 species. He has likewise described the following species of phalangium and oniscus. Pha langium spinosum and aculeatum ; oniscus testudo, gracilis, thoracicus, and squillarum. He has also descri bed several species of British molusca, a tribe of sea-animals that have not been so much studied as they deserve. The following are those which he has described: Bulla hydatis. This is a very singular animal, not referable to any class in the Systems Naturæ. Doris longecornis and nodosa; Aphorodita clava; Amphitrite infundibulum; Terebella tentacula; Nereis pinnigera; Halothuria pentactes; and Lucernaria auricula. Of most of these animals he has given figures.

It has been generally believed that there are two species of the vespertilio ferrum equinum, or horse-shoe bat, differing chiefly in size. But the smaller species has been seldom seen, and by some has been reckoned merely a va riety. Mr Montagu has found both of these species together in the south of England, and has ascertained them to be quite distinct. He has published a description of both, confining the trivial name ferrum equinum to

the large species, and calling the smaller vespertilio minutus. He like wise discovered the vespertilio barbastellus in Devonshire. It was known to exist in France, but had not been suspected in England previous to his discovery.

The birds described under the names of falco cyaneus and falco pygargus, and called in English henharrier and ringtail, had been suspected to be only the male and female of the same species; but the conjecture had not been verified, and on that account they had been described by naturalists as distinct. Mr Montagu has at last decided the point, and ascertained that the birds constitute only one species, the hen-harrier being the male and the ringtail the female. A servant of the Rev. Mr Vaughan found a nest of these birds, containing three young ones and an addle egg. They were brought up by Mr Montagu till their sex and plumage were distinct, and the result was the discovery above mentioned.

Mr Montagu has found the sylvia Dartfordiensis, or Dartford warbler, in England, and has corrected some mistakes committed by Buffon in his

account of this bird, who described it under the name of Sylvia Provincialis, and affirmed that it was accus tomed to conceal itself among cabbages from its enemy the bat. Mr Montagu has discovered likewise, that the following birds are natives of England: Ardea Equinoctialis, little white heron; Tantalus Viridis, green ibis; Scolopax Noveboracencis, red-breasted snipe; Glancola Austriaca, Austrian pratincole.

These are the principal additions that have been made to British zoology. Some animals from the East Indies and South Sea islands have been likewise figured and described; as, for example, two new species of Didelphis from Van Diemens Island, by Mr Harris, and the Ursus Indicus, or Indian Badge, by Colonel Hardwicke.

Such are the principal improvements that have been made in Chemistry, Botany, and Zoology, during the period to which our history extends. In the other departments of science the improvements have been less striking; we may therefore, without any breach of propriety, reserve our account of them for the scientific department of our succeeding volume.