Page images
PDF
EPUB

however, the colour of which it destroys, as that of the red rose. The effect of the gas upon these colours is similar.

The saturated solution allows the gas to escape at a very moderate heat, and by boiling, the greater part is expelled, though the liquor remains acid, apparently from the presence of sulphuric acid. It is singular that it is not expelled by freezing, but still remains combined with the ice, and renders it so heavy that it sinks in water. This act shows that that this has, comparatively with others, little tendency to pass into the aeriform state. The freezing of the solution takes place at a few degrees below 32.

When two parts of the gas are mix. ed with one part of oxygen gas, if the mixture is kept over mercury, they do not act on each other. But if a small portion of water is introduced, they gradually combine and form sulphuric acid, a fact explained by Mr. Murray, on the supposition that the water exerts a strong disposing affinity to this acid, or, to speak more intelligibly, according to the explanation of disposing affinity given under our article CHEMISTRY, the water attracts the sulphurous gas, and, by depriving it of its state of elastic fluidity, renders it capable of more readily uniting

with the oxygen, which is also effected by a like action of the water; and as these combine into sulphuric acid, which is more soluble than the sulphurous, the process is still more facilitated, and goes on progressively until the effect is completed. By passing s mixture of oxygen gas and sulphurous acid gas through a tube heated to redness, they instantly combine, and sulphuric acid is formed.

This acid combines with facility with the alkalies, forming salts denominated sulphites, which differ considerably from the salts formed by the sulphuric acid. Their taste is sulphurous; they are decomposed by a high temperature, their acid being either expelled, or a portion of sulphur being driven off, in which case they become sulphates; they are also decomposed by the greater part of the acids, and then the sulphurous acid is disengaged with effervescence. The alkaline sulphites are more soluble than the sulphates in water, the earthy sul phates less so. All these salts are converted into sulphates by exposure to the atmospheric air, or by the action of any snbstance capable of affording them oxygen. They suffer this change, for example, by deflagration with nitre. See SULPHUROUS ACID.

TABLE,

Showing the absolute Weight and specific Gravities of Gases, and the Quantity of each absorbed by Water.

Temperature of 60° Fahrenheit, Barometer 29.8.

B. Brisson; Cr. Cruickshank; D. Davy; Dal. Dalton; Dei. Deiman; H. Henry; K. Kirwan; S. Shuckburgh; T. Thomson; Th. Thenard; Tr. Tromsdorff.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small]

Of temperature 100° Fahrenheit, and force = 30 inches of Mercury.

† Of temperature 190° Fahrenheit, and force

[ocr errors]

30 inches of Mercury.

GASSENDI, (PETER,) in biography, a very eminent philosopher and mathematician, and one of the most illustrious ornaments of France, in the seventeenth century, was born in the year 1592, at Chanterseir, about three miles from Digne, in Provence. He afforded early evidence that he possessed a lively and inquisitive genius, and a happy memory, which determined his parents, though they were but in moderate circumstances, to bestow upon him the best education in their power. When he was only four years of age, in consequence of the pious impres sions which had been made on his mind, he was accustomed to act the preacher among his playmates; and soon after wards he began to discover his taste for astronomy, by taking delight in gazing at the moon and stars, when the atmosphere was unclouded.

The pleasure which he took in contemplating the heavens often led him to retire to unfrequented spots, where he might feast his eyes without being disturbed; by which means his parents were frequently obliged to seek for him, under anxiety and apprehensions for his safety. When he was of a proper age to be sent to school, he was placed under the instructions of an excellent master at Digne, where he made a rapid progress in the knowledge of the Latin tongue, and also acquired a pre-eminence over his school-fellows in rhetorical exercises. Afterwards he was sent to study philoso phy for two years, under an able professor at Aix; and at the expiration of that period returned to his father's house at Chantersier.

He had not been long at home, however, before he was invited to teach rhetoric at Digne, when not quite sixteen years of age; and about three years afterwards he was appointed to fill the vacant chair of philosophy in the University of Aix. During his residence at Digne, he had sedulously prosecuted his studies in the learned languages, mathematics, and astronomy, and after a dili gent examination of the different systems of philosophy among the ancients, embraced that of Epicurus, of which he afterwards proved himself the most ingenious defender in modern times. When he entered upon his philosophical professorship at Aix, notwithstanding that the authority of Aristotle was still acknowledged in almost all the public schools, Gassendi, after the examples of Vives, Ramus, and others, ventured publicly to expose the defects of his system. VOL. V.

The lectures which contained his censures of the Aristotelian philosophy, de. livered in the indirect form of paradoxical problems, were published under the title of "Exercitationes Paradoxica adversus Aristotelem." This work, which gave great offence to those who still retained their predilection for scholastic subtlety, obtained the author no small degree of reputation with several learned men, particularly with Nicholas Peiresc, the president of the University at Aix, who determined to procure for him a situation in the church, in which he should be enabled to pursue his favourite studies at his leisure, and without any molestation. After Gassendi had entered into holy orders, through the interest of Peiresc, and Joseph Walter, prior of Vallette, he was promoted to a canonry in the cathedral church of Digne, and admitted to the degree of doctor of divinity; and afterwards received the appointment of warden, or rector of the same church. In consequence of these promotions, he resigned his professorship at Aix, and retiring to Digne, applied himself closely to his philosophical and astronomical pursuits.

Among his other works which he wrote in this place, was a second book of his "Exercitationes Paradoxicæ," intended to expose the futility of the Aristotelian logic. It was his first intention violent opposition which he met with to pursue the plan still further; but the from some of the zealous and powerful advocates for the authority of Aristotle, induced him to desist from all direct attacks upon his philosophy. Still, however, he professed his attachment to the system of Epicurus, and defended it with great learning and ability.

From Lucretius, Laertius, and other ancient writers, he undertook to frame a consistent scheme of Epicurean doctrine, in which the phenomena of nature are immediately derived from the notion of primary atoms. But he was aware of the fundamental defect of this system, and added to it the important doctrine of a divine superintending mind, from whom he conceived the first motion and subsequent arrangement to have been derived, and whom he regarded as the wise governor of the world. He strenuously maintained the atomic doctrine, in opposition to the fictions of the Cartesian philosophy, which were at that time obtaining great credit; and particularly asserted, in opposition to Des Cartes, the doctrine of

PP

a vacuum. On the subject of morals, he explained the permanent pleasure or indolence of Epicurus, in a manner perfectly consistent with the purest precepts of virtue. In the year 168, Gassendi, for the sake of extending his acquaintance with the learned, visited Holland, where his philosophical and literary merit soon procured him many admirers and friends. While he was in that country he wrote an elegant and judicious apology for his friend, the learned Mersenne, in reply to the censures of Robert Fludd, on the subject of the Mosaic philosophy. After his return to France, he continued his philosophical, and particularly his astronomical studies, pursuing, with great care, a series of celestial observations, in order to complete his system of the heavens. Being called by a law-suit to Paris, he there formed an acquaintance with the men most distinguished for science and learning in that capital, and by his agreeable manners, as well as reputation, secured the esteem of persons of high rank and quality, and in particular of Cardinal Richelieu, and of his brother the Cardinal of Lyons. Owing to the application and interest of the latter, in the year 1645, Gassendi was appointed regius-professor of the mathematics at Pa

ris.

This institution being chiefly in tended for astronomy, our author read lectures on that science to crowded auditories, by which he acquired great popu larity, and rose to high expectations.But the fatigues of that appointment were more than his strength, already reduced by too intense application, was able to bear; and having caught a cold, which brought an inflammation upon his lungs, he was obliged, in the year 1647, to quit Paris, and to return to Digne for the benefit of his native air. After having his health in some measure re-established by the intermission of his studies, in the year 1653 he returned again to Paris, where he published the lives of Tycho Brahe, Copernicus, Purbach, and Regiomontanus; and then resumed, with as much intenseness as ever, his astronomical labours. His feeble state of health, however, was now unequal to such exertions, which brought on a return of his disorder under which, with the aid of too copious and numerous bleedings, he sunk in 1655, when in the sixty-third year of his age. A little before he expired, he desired his secretary to lay his hand upon the region of his heart; which when he had done, and remarked on the feeble state of its pulsation, Gassendi said to

him, "You see how frail is the life of man!" which were the last words he uttered. He is ranked by Barrow among the most eminent mathematicians of the age, and mentioned with Galileo, Gilbert, and Des Cartes.

His commentary upon the tenth book of Diogenes Laertius affords sufficient proof of his profound erudition, and his deep skill in the languages.

We have already mentioned his opposition to the philosophy of Des Cartes, by which he divided with that great man the philosophers of his time, almost all of whom were either Cartesians or Gassendists. At one time a coolness took place between those two eminent charac ters, in consequence of irritating expressions which had escaped from both their pens, during the course of their philosophical warfare. The Abbé d'Estrees, afterwards Cardinal, with the design of bringing about a reconciliation between them, invited them both to dinner, in company with many of their common friends, among whom were father Mersenne, Roberval, the Abbé de Marolles, &c. At the time fixed, all the expected guests made their appearance, excepting Gassendi, who, during the preceding night, had been attacked by a complaint, which prevented him from venturing abroad. As the cause of his absence was explained after dinner, the Abbé d'Estrees carried his whole company along with him to Gassendi's apartments, where they had the pleasure of hearing the two philosophers make mutual acknowledgments of their improper warmth and irritability, and generously declaring, that whatever difference in opinion might afterwards subsist between them, it should produce no unfavourable effect upon their friendship.

severe

Gassendi was the first person who observed the transit of Mercury over the sun. Kepler had predicted that it would take place on the 7th of November, 1631. Gassendi, who was then at Paris, made due preparations to observe it, and after having for some time mistaken the appearance of that planet for a solar spot, became at length sensible of his error by the rapidity of its movement; and took care to calculate the time of its egress from the sun's disk, as well as its distance from the sun's vertical point.

From Gassendi's letters, it appears that he was often consulted by the most celebrated astronomers of his time, as Kepler, Longomontanus, Snell, Hevelius, Galileo, Kircher, Bulliald, and others;

and his labours certainly entitle him to a high rank among the founders of the reformed philosophy. Gassendi possessed a large and valuable library, to which he added an astronomical and philosophical apparatus, which, on account of their accuracy and worth, were purchased by the Emperor Ferdinand III. and afterwards deposited, with other choice collections, in the Imperial Library at Vienna. The MSS. which he left behind him, and the treatises formerly published by himself, were printed together, accompanied by the author's life, and published by Sorbiere, in six volumes folio, 1658.They consist of the philosophy of Epicurus; the author's own philosophy; astronomical works; the lives of Periesc, Epicurus, Copernicus, Tycho Brahe, Purbeck, Regiomontanus, John Muller, &c. a refutation of the meditations of Des Cartes; and epistles, and other treatises.

GASTEROSTEUS, the stickle-back, in natural history, a genus of fishes of the order Thoracici. Generic character: body carinate on each side, somewhat lengthened, and covered with bony plates; dorsal fin single, with distinct spines between it and the head; ventral fins behind the pectoral, but above the sternum. There are thirteen species. G. aculeatus, or three spined stickle-back, is found in almost all the fresh waters of Europe, and is about three inches long, and in the beginning of the summer displays the most beautiful combination of bright-red, fine olive green, and silvery whiteness. It is extremely active and rapid, and is particularly injurious in fish ponds, as it devours the spawn of the fish. It is highly voracious, and is reported to have swallowed in the space of five hours, seventyfour young dace, about a quarter of an inch in length. In the fens of Lincolnshire, these fishes appear in immense numbers, and have been frequently sold at the rate of a halfpenny per bushel. They have been often most successfully applied as manure for land.

GASTRIC juice, a fluid of the utmost importance in the process of digestion. It does not act indiscriminately on all substances, nor is it the same in all animals, nor does it continue always of the same nature, even in the same animal; it changes according to circumstances. No certain facts have yet been established as to the nature of the gastric juice: it is however completely ascertained, that it acts with a chemical energy in dissolving food it attacks the surfaces of bodies,

unites to the particles of them, which it carries off, and cannot be separated from them by filtration. It operates with more energy and rapidity the more the food is divided, and its action is increased by a warm temperature. The food is not merely reduced to very minute parts; its taste and smell are quite changed; its sensible properties are destroyed, and it acquires new and very different ones. This fluid does not act as a ferment, it is a powerful antiseptic, and even restores flesh already putriefied. Two things are well known with respect to the substances contained in the stomach. 1. They contain phosphoric acid; and 2. they have the power of coagulating milk, and the serum in the blood. What the coagulating substance is, has not been discovered, but it is supposed to be not very soluble in water, since the inside of a calf's stomach, after being steeped in water six hours, and then well washed, still furnishes a liquor, on infusion, which coagulates milk.

GASTROBRANCHUS, in natural history, a genus of fishes, of the order Cartilaginei. Generic character: mouth beneath, furnished with pectinal teeth, in a double row on each side: body eelshaped, carinate beneath by a soft fin, two ventral spiracles. G. cœcus, or the hag-fish, is about five inches in length, in the European seas, but, in those of India, attains the length of a common cel. Its appearance is very similar to that of the lamprey. It is characterized by the circumstance of exhibiting no traces of the existence of such an organ as the eye. It is reported by naturalists, that the hag-fish will often enter the mouths of fishes fixed on the hook of the angler, and gnaw a passage through their bodies, devouring all but the bones and skin. Its substance is so highly glutinous, that a large vessel of sea water will, in a short time after the living cœcus is placed in it, become of the consistence of jelly.

GATE, in architecture, a large door, leading or giving entrance into, a city, town, castle, palace, or other considerable building or a place giving pas sage to persons, horses, coaches, or wagons, &c.

GAVELKIND, a tenure or custom belonging to lands in the county of Kent, by which the lands of the father are, at his death, equally divided among all his sons; or the land of a deceased brother, in case he leaves no issue, among all the brethren. This is by some called

« PreviousContinue »