the summer: but was not seriously indisposed till within a few weeks of his death. He then became perfectly aware of the event that was approaching; and with his usual tranquillity and benevolence of nature, seemed only anxious to point out to the friends around him the many sources of consolation which were afforded by the circumstances under which it was about to take place. He expressed his sincere gratitude to Providence for the length of days with which he had been blessed, and his exemption from most of the infirmi ties of age, as well as for the calm and cheerful evening of life that he had been permitted to enjoy, after the honourable labours of the day had been concluded. And thus, full of years and honours, in all calmness and tranquillity, he yielded up his soul, without pang or struggle, and passed from the bosom of his family to that of his God!

GASPARD MONGE, so celebrated for his mathematical talents, and useful practical discoveries, was born at Beaune, in the province of Burgundy, in the year 1746. At the age of nineteen, he had so much improved the stock of knowledge which he received at the school of the priests of the Oratory, at Lyons, that he was appointed teacher of Natural Philosophy in the Military School of Mezières, and soon afterwards made a Professor. In order to bring him to Paris, Monge was in 1780 appointed assistant to Bossut, Professor of the Hydrodynamic Course, instituted by Turgot. The same year he was admitted into the Academy of Sciences; and on the death of Bezout in 1783, he was chosen to succeed that celebrated examiner of the naval service. In this situation Monge had been several times invited by the Marquis de Castries

to write an elementary course of mathematics for the youths of the naval service; but, from a motive highly honourable to his memory, he invariably refused to comply. "Bezout," said he, “has left a widow with no other fortune than her late husband's works, and I do not wish to take away the bread from the widow of one who has rendered important services to science and to his country." The only elementary work which he published was his Traité de Statique, which is a model of logical precision, clearness, and simplicity.

In 1792, when France was menaced with invasion, and when the public distress called for the talents and courage of the superior classes, Monge was created Minister of the Marine. In this new and difficult situation, he spent his days in giving instructions and superintending the workmen, and his nights in writing his Treatise on the casting of artillery (Fonte de Canons,) a book intended for the use of the directors of the public founderies.

Monge's next great work was planning a system of education, which should combine a general course of Natural Philosophy with the more practical studies of engineering, and which ultimately led to the establishment of the Polytechnic School. In the execution of this project, Monge spared neither time nor exertions, delivering lectures and giving drawings, with rules for the regulation of conduct, of time, different kinds of study, &c. As fellowlabourers in this design, we discover the names of Laplace, Berthollet, Fourcroy, Chaptal, and others.

After completing the arrangements of the Polytechnic School, Monge was sent into Italy with his friend Berthollet, now a Count and Peer of France, to superintend the

transportation of the prints, pictures, statues, &c. plundered under cover of the treaty of Tolentino; but these monuments had hardly entered Paris, when Monge was appointed to preside in the Commission of the Sciences and the Arts destined to accompany the expedition to Egypt. Here he was indefatigable in his exertions; visited the Pyramids twice; saw the obelisk, and the grand ruins of Heliopolis; studied the remains of antiquity scattered round Cairo and Alexandria; and during a tedious march through the desert, discovered the cause of that wonderful phenomenon known by the name of the mirage *.

After pursuing his labours, for some time, with unabated vigour and enthusiasm, Monge returned to France with Napoleon, who, when First Consul, created him successively a Senator and Count of Pelusia in Egypt.

When Napoleon abdicated, Monge

fell into disgrace with the new government, which expelled him from the French Institute, in opposition to an express ordonnance, which enacted that every member of the ancient Academy of Sciences should be of right a member of the newly regulated Institute. Monge, already seventy years of age, was so struck by this pitiful outrage, that he sunk into a state of mental depression, and soon after expired. He appears to have been a man of original talents, great activity, and indefatigable application; and in a political point of view, his gratitude to his fallen master renders him infinitely more respectable than many of his contemporaries, who had the dexterity to lay aside their old principles and habits when the tide of fortune turned, and to reconcile themselves to the Bourbon Dynasty, by traducing and vilifying the man to whom they had so often offered up the incense of the most servile adulation.

LIGHT AND HEAT.

On the interesting subjects of Light and Heat, no great quantity of additional information was brought into view during the course of this year. It will be recollected, that, some years ago, Morichini had performed a set of experiments, by which he professed to have discovered that steel wire, when exposed for a certain time to the violet rays of the sun, becomes magnetised. These experiments have been repeated by various philosophers, generally without success; though there are some who affirm that they have verified Morichini's discovery. The reality of this power of the violet rays was, therefore, very generally called in question, till it was nounced in the Bibliothéque Universelle, that the late Professor Playfair had witnessed a successful experiment of this kind. Since the time of this announcement, various other persons, and, among the rest, M. Dhombres Firmas, have tried this experiment, and have uniformly failed. The success of Morichini's experiment must, therefore, have, in all probability, been owing to the

position of his needles; for, if they had been placed nearly in the magnetic meridian, a certain temperature preserved for a certain time may be conceived to be capable of inducing permanent magnetism,

The most remarkable paper on the subject of heat is an early production of Professor Leslie, "On Heat and Climate," which had been read at two meetings of the Royal Society as far back as the year 1793, but was first published in the "Annals of Philosophy" for July 1819. The novelty of the views developed in this ingenious performance, its total deviation from the opinions generally received at the time, and the disregard of authority evinced by the author, appear to have startled the Committee of the Royal Society, and prevented them from inserting it in their Transactions. As far as Mr Leslie was concerned, this was perhaps fortunate. It induced him to re-consider the subject, and probably led to most of the investigations afterwards given to the world in his

found thinker and original discoverer. Into the peculiar doctrines develop. ed in this ingenious paper, it would be obviously superfluous to enter at present; but there is one operation which we beg leave to notice, because we consider it inaccurate in point of fact. Professor Leslie says, that, on descending into the deepest mines, no sensible increase of temperature is ever observed. Now, the fact is, that, in the copper mines of Cornwall, it is no uncommon thing to find the air hot enough to raise the thermometer to 100°; and that, in the salt mines of Cheshire, the miners work without their clothes, and rather complain of heat than cold. Dr Thomson supposed the temperature of the air in the salt mine at Nantwich to range between 80° and 90°; and it will be seen from a table published by Mr Bald, that the air and the water at the bottom of the deep coal mines in Durham, Cumberland, Northumberland, and Stafford, are from 12° to 19° higher than at the surface of the earth. Whether we attempt to explain this difference by the theory of subterranean or central fire, or by any other hypothesis, the fact itself is undoubted; and we are rather surprised that a philosopher so remarkable as well for the accuracy of his information, as for the delicacy of his experiments, and the originality of his views, should have fallen into such an error.

GALVANISM.

Dr Hare, of America, has published a theory of galvanism, differing considerably from all those hitherto started. According to him the galvanic fluid is a compound of electricity and caloric. The electricity is increased by the number of pairs of

plates; and when this number is very great, as in Deluc's column, the calorific effects become evanescent. The caloric is evolved, by the increase of surface; and he has shown that it may be very intense, even when only a single pair of plates is used. Upon this principle, he constructed a battery, which produced intense ignition without any electrical phenomena.

HYPOSULPHUROUS ACID AND ITS

COMBINATIONS.

But one of the most important in. vestigations connected with experimental chemistry, which this year produced, is that of Mr Herschell, on the hyposulphurous acid and its compounds. An accident first led him to the prosecution of the inquiry, which has conducted to some inte resting results. Having set aside, for a few days, a solution of hydrogu. retted sulphuret of lime, he was struck by observing a bitterness in the liquid when almost wholly decomposed and colourless, similar to that of magnesia, the presence of which he at first suspected, but was soon undeceived. The liquid had lost its property of precipitating iron or copper from their solutions in the state of sulphurets, though it still gave a copious precipitate to the carbonated alkalies, and of course retained lime in some state of union with an acid, which could not be either the sulphuric or sulphurous, neither of these forming double salts with lime. The inquiry now became interesting, and was pursued with great success by the ingenious chemist we have just named.

The hyposulphurous acid not being capable of a separate existence, or at least not being procurable in

that state in any quantity, or without great difficulty, its characters can only be ascertained by examining its combinations with different bases. Some of the principal of these will be here given. The hyposulphites are easily soluble in water, and their solutions have either an intensely bitter, or intensely sweet taste. When heated to a degree below redness, they are decomposed; and while sulphur separates, a sulphite, or in some cases a sulphuret of the base remains. The action of nitric acid, or a stream of chlorine passed through their solutions, converts them into sulphates. The hyposulphites and their solutions are decomposed by all other acids, except the carbonic, especially when heated with them. They precipitate lead from its solutions in white powder, which is hyposulphate of lead. Oxi-nitrate of silver, and nitrate of mercury, dropped into a dilute solution of any hyposulphite, precipitate their respective metals in the state of sulphurets. Nitrate of bismuth when heated, undergoes the same change; while solutions of manganese, iron, zinc, copper, tin, suffer no such precipitation. But one of the most remarkable properties of the hyposulphites is that which their solutions possess of dissolving muriate of silver, and retaining it in considerable quantity in permanent solution.

We shall now proceed to give a condensed description of the salts which Mr Herschell succeeded in forming, beginning with that of lime, which is the most readily obtained in a state of purity.

Hyposulphite of lime may be formed by exposing the hydroguretted sulphuret of that alkali in a flat vessel, for ten or twelve days to the air, or by boiling, for a considerable time, the sulphite of lime with sul

phur in a large quantity of water. This salt usually crystallizes into irregular six-sided prisms, whose faces are inclined to each other at angles of 141° 39′, 110° 45', and 107° 36′. They refract doubly, and dissolve readily in water at the temperature of 37°, that liquid dissolves nearly its own weight of them, and during the solution the thermometer sinks to 31°. At 50°, the specific gravity of a saturated solution is 1.300; and when the temperature is 60°, and the specific gravity 1.114371, the solution contains 0.2081 of its own weight. These crystals are not altered by exposure to air, unless it be very dry.

From Mr Herschell's experiments, this salt appears to be composed of

2 atoms hyposulphurous acid, 6.000 1 atom lime, 6 atoms water,

3.625

6.750

16.375

Hyposulphite of potash is readily prepared, either by precipitating that of lime by the carbonated alkali, or immediately decomposing hydrosulphuret or hydroguretted sulphuret of potash by sulphurous acid, and evaporating to a pellicle. It then crystallizes into a confused mass of spicule. It has a penetrating taste like nitre, succeeded by bitterness, and deliquesces readily when exposed to the air. When heated, it dries down to a white mass, then takes fire, and burns like a piece of tinder.

Hyposulphite of soda may be formed in precisely the same manner. On cooling, it crystallizes in silky tufts radiating from centres, which at length extend through the whole liquid, and become almost solid. Its taste is intensely bitter and nauseous. When heated, it first undergoes the watery fusion, then dries into a white mass, and at length takes