liant period, than that, in which it is our honour and happiness to live. Systems. Although there have been many schemes and hypotheses concerning the heavenly bodies, yet there have been only four which have attained to any thing like authority and permanence in the world. The first of these is the Ptolemaic system, so called from Claudius Ptolemy, a native of Pelusium, in Egypt, who made bis last astronomical observation, on Wednesday the 2d of February, 141. The system which is distinguished by his name, is contained in his celebrated book, called "The Great Syntaxis;" which book reduces to order the observations of the ancient astronomers, and is, I believe, the first book which ever set forth regular tables of the sun, moon, planets, and fixed stars. The Ptolemaic system supposes the earth to be at rest in the centre, and that the heavens, solid and incorruptible, revolve round it from cast to west, carrying along with them all the planets and fixed stars. The diverse motion of the planets, this system accounts for, by assigning to each of them its respective orb; and the outermost orb, the primum mobile of the ancients, was supposed to communicate motion to all the rest. Although philosophers of the present day smile at this system as absurd and impossible; yet it should be remembered, that the world was content with it for many ages; and that it was once looked upon as founded on invincible demonstration, and as placed beyond the reach of controversy and the fluctuations of opinion: a circumstance this, which calls for a degree of modesty and hesitation, about much, very much, of our knowledge. The second system is called the Tychonic system, from its inventor, Tycho Brahe, a noble Dane, who acquired great celebrity as an Astronomer, in the latter half of the sixteenth century. In this system there are supposed to be two centres; the earth, the centre of the universe or firmament of stars, around which they revolve in 24 hours; and the sun, the centre of the orbits of Mercury, Venus, Mars, Jupiter, and Saturn; around which they are carried in their respective periods, the same as the sun is supposed to be carried round the earth in its solar year. This hypothesis was so embarrassed and perplexed, that few persons have embraced it; and no wonder, if, as some of the biographers of Tycho intimate, his vanity to become the founder of a system, had too large a share in its production. The third system is denominated the Cartesian, from its author Des Cartes, a French philosopher, of the seventeenth century; and a man of a speculative, bold, prodigious genius. His reputation in foreign nations appears on his monument, which consists of four faces, inscribed with so many encomiums. It was erected at Stockholm, where he died in the year 1650. The system of Des Cartes, though very artfully contrived, yet carries with it more of the air of a ROMANCE, than of a just and solid philosophy. It supposes the planets to be driven round the sun, in a vortex or whirlpool of subtile matter; and that the vast regions of space being full of this subtile matter, there is an infinite number of planetary vortices, every fixed star being the centre of its distinct vortex. That this whirlpool scheme of the Cartesians is a mere fiction, is evident from the following considerations. 1. That comets, which pass very freely in the heavenly spaces, taking their prodigious journeys to and from all parts, move in orbits which intersect the orbits of the planets at all angles. So that if the comets move in a vortex, as well as the planets, there would be two vortices, moving in different, perhaps in opposite directions, in one and the same place, at one and the e time; which is absurd. 2. According to the laws of me. nics, it is evident, that if'tter of any kind move in a vortex, which is elliptical, it must move the swiftest in that part of the ellipse which is the most strait, narrow, and conressed. But according to the laws of Astronomy, the planets which move in elliptical orbits, when in that part of their orbits which is the most contracted and compressed, viz. in aphelion, then move the slowest. 3. This doctrine of vortices is not supported by any phenomena of nature, with which we are acquainted. "If," says Sir Isaac Newton, "three equal round vessels be filled, the one with water, the other with oil, the third with molten pitch, and the liquors be stirred about till they have alike acquired a vorticle motion; the pitch by its tenacity will lose its motion quickly; the oil, being less tenacious, will keep it longer; and the water, being least tenacious of the three, will keep it longest, but yet will soon lose it. Whence it is easy to understand, that if many contiguous vortices of molten pitch were each of them as large as those which are supposed by some to revolve around the sun and fixed stars; yet these and all their parts, would, by their stiffness and tenacity, communicate their motion one to another, until they all rested among themselves. Vortices of oil, or water, or some more fluid matter, might continue longer in motion; but unless the matter were destitute of tenacity, and attrition of parts, and communication of motion, (which is not to be supposed,) the motion would constantly decay, till finally there would be an universal rest." It would have been a waste of time thus to combat the Cartesian hypothesis, but for the very recent attempts which have been made to revive it. The temerity with which Sir Richard Philips has discarded the Newtonian philosophy, and substituted that of Des Cartes, has led some to doubt whether the philosophic knight-errant be in reality sincere. But whether Sir Richard, and the rest of the Cartesian astronomers, be sincere or insincere, it is manifest their situation calls for our philosophic commiseration: the poor fellows having got into a whirlpool, from which they cannot get out, are carried round and round a centre of absurdity, in a vortex of nonsense! The fourth system, which we do not | hesitate to pronounce the true one, is that theory of Astronomy which now almost universally prevails, and which is certainly destined to be received as the rule of the sun, moon, and stars, as long as sun, and moon, and stars, endure. This system has sometimes been classically denominated the Pythagorean system, because it was understood and taught by Pythagoras, an ancient Greek philosopher. It is a remarkable fact in the history of science, that the true scheme of the universe should have been known and published by Pythagoras, more than 500 years before the Christian æra; and then that it should slumber and be superseded for two thousand years. The true theory of the heavens was revived in the sixteenth century, by Nicholas Copernicus, a prebend of Thorn, in Poland; and hence is called the Copernican system. Copernicus died in the year 1543: he was an excellent classical scholar; a profound mathematician; and a most acute and laborious observer of celestial phenomena. His book, "De orbium cælestium revolutionibus," which contains his theory, was a work of long and arduous toil; it was printed under the management of two of his philosophical friends, and a copy of it was put into his hands just before he expired. But the denominating terms, Pythagorean and Copernican, are now giving place to the more Anglicized, and perhaps more significant appellative, Newtonian. In the latter part of the seventeenth century, it pleased the Almighty, in pity to the darkness of mankind, and to throw a stronger light upon his own matchless and amazing works, to visit our hemisphere with that bright and steady luminary, the great Sir Isaac Newton. Endowed with a compass of soul, high, and vast, and profound ;--with a penetration which could look through nature, and scan her mighty laws ;-with an intellectual industry equal to the most gigantic enterprise; -with a temper calm, tranquil, and devout,-the immortal Newton rose far above the common level, even of learned and scientific men; and by his single power, reared a fabric of mathematical and experimental philosophy, which must for ever stand the boast of true wisdom, and the terror of idleness, ignorance, and pride. (To be concluded in our next.) ADVANTAGES OF CONCESSION. IN great matters of public moment, where both parties are at a stand, and both are punctilious, slight condescensions cost little, but are worth much. He that yields them is wise, inasmuch as he purchases guineas with farthings. A few drops of oil will set the political machine at work, when a tun of vinegar would only corrode the wheels, and canker the movements. CHEMICAL ESSAYS,-BY STUDIOSUS. MR. EDITOR. Sir,-If you think the following Essay on Oxygen, worthy a place in the columns of your valuable miscellany, for which it has been purposely written, an early insertion will gratify. Should it meet your approbation, it shall be followed by a second, on Nitrogen, and a third on Atmospheric | Air. I am Sir, With the most profound respect, Essay 1st.-Oxygen. manner. collected over water in the following The pneumato-chemical, or pneumatic apparatus, was first invented by Dr. Priestley, which consisted of nothing more than a common tab, with a shelf in it. used a most elegant apparatus, which He afterwards the Duke of Rochefoucault sent him. This trough may be made of any size, but should not be less than a foot in depth; the shelf is to be placed on one side only, and about three inches from the top. Having filled the whole with water, for at least an inch above the shelf, we are next to fill a jar or glass receiver with common water; and having placed the open end of it the beak of the retort into the pneuupon the shelf, we are to introduce mato-chemical, immediately under the open end of the receiver, when airbubbles will be seen to arise through the water into the receiver, and displace the water. In this way we may proceed till we have obtained a sufficiency for use. 3d. From the Hyperoxymuriate of soda, or potass. Put into a retort any quantity of either of these salts, apply the heat of a lamp, and Oxygen, in the greatest purity, will be liberated, which may be colA-lected over water, as previously described. Nitrate of potass is another substance which is frequently used for obtaining Oxygen Gas; but trusting that the foregoing processes will be found sufficient, we will now proceed to investigate its properties. THE word Oxygen is of Greek extraction, and signifies to generate acidity. Oxygen Gas was first discovered by Dr. Priestley, in 1774, who called it dephlogisticated air. In 1775, it was discovered by Mr. Sheele, without any previous knowledge of the discovery of Dr. Priestley. Mr. Sheele gave it the name of empireal air. It first received the name of vital air from Condorcet, and that of Oxygen Gas from Lavoisier. We are acquainted with many substances, from which Oxygen Gas may be obtained. mongst others, it may be procured from the green leaves of vegetables, from the oxydes of manganese, lead, or mercury, from the hyperoxymuriate of soda, or potass. 1st. From the fresh leaves of vegetables. Fill a large receiver, or bell glas, with water, and invert it on a broad dish, which is to be likewise filled with that fluid; introduce fresh gathered leaves; expose the whole to the rays of the sun, and pure Oxygen will be disengaged, which will gradually displace all the water, and occupy its place. 2d. From the black oxyde of manganese. Put into a retort of glass any quantity of the black oxyde of manganese, add as much sulphuric acid as will form the whole into a thin paste, apply the heat of a lamp, and Oxygen Gas, sufficiently pure for all common purposes, will be liberated. If we are wishful to obtain it on a more extensive scale, the following process will be preferable. Procure an iron retort, and having introduced a sufficient quantity of the black oxyde of manganese, expose the retort to a red heat, and Oxygen Gas will be evolved in abundance, which may be No. 36.-VOL. IV. less, like common air. Like common Oxygen Gas is invisible, and colourair, it is also highly elastic, and capable of indefinite expansion and compression. Its specific gravity is 135°, it is therefore 740 times lighter than the same bulk of atmospheric air. Its weight to that of atmospheric air being as 1103 to 1000. It is not sensibly absorbed by water, though left in contact with that fluid for a great length of time. It is entirely absorbable by the combustible bodies, which, in consequence of disengaging its caloric and light, produce heat and flame. If combustible bodies be burnt in Oxygen Gas, and the experiments are conducted with accuracy, we shall find the product increased in weight just the quantity of Oxygen consumed. By experiments, which shall be noticed in a following Essay, it hath been proved that Oxygen constitutes about 22 in every 100 parts of atmospheric C air, or, if the calculation be made by the atmosphere, passes from its origiweight, 23 parts. It has also been ↑ nal yellow colour, through several difproved beyond a doubt, that no ani- ferent shades, till it assumes that of mal whatever can live for a moment, a dark purple; this I have had shewn in air previously deprived of all its me several times by an intelligent Oxygen; and that animals will live dyer, of Manchester; and it is a well six times as long in the same quantity known fact, that when woollen goods of Oxygen Gas, as in common atmo- are taken out of an indigo vat, they spheric air. Oxygen is therefore ne- are generally of a beautiful green, but cessary to animal life. in the course of one or two minutes they have absorbed a sufficient dose of Oxygen, to convert them into a dark blue. Oxygen necessary to combustion.—Introduce into a glass jar, or receiver, filled with Oxygen Gas, a lighted taper, and it will burn with great bright- Germination. That germination does ness, and produce a much greater not depend upon the seed alone, but degree of heat than if burnt in atmo- requires some external cause to effect spheric air. Blow the taper out, re- it, is now generally acknowledged. introduce it, and the flame will be in- Seeds will not germinate, unless a stantly rekindled. If we introduce a certain degree of heat and moisture lighted taper into a well-closed jar of have access to them; nor will they common air, it will be almost im- then germinate, unless atmospheric mediately extinguished; if we re- air be present. It has been proved peat the experiment, substituting Ox- by well-conducted experiments, that ygen Gas, we shall find it to burn seeds will not germinate in the vacusome time. We have said that Oxy-um of an air-pump, but as soon as gen is not absorbed by water; but, by means of strong pressure, however, it may be made to take up half its own bulk, which it will retain in solution. Though water thus impregnated does not essentially differ from common water, in either taste or smell, yet it has been administered in several diseases with decided success. Dr. Higgins caused a young man to breathe Oxygen Gas for several minutes, when his pulse, which was at 64, soon rose to 120 beats in a minute. It is upon this principle that pure Oxygen has been used with such success in suspended animation. Effect of Oxygen upon the blood. The blood when it has arrived at the lungs is of a dark purple colour, which is owing to the superabundance of carbon which it has received in its course of circulation through the body; it here becomes converted into a red oxyde, by the great quantities of Oxygen it is continually receiving through the agency of the lungs, and becomes of a bright and florid red. Put a little blood into a small vessel of Oxygen Gas, shake the vessel, and the gas will have become partly absorbed by the blood, which will assume a bright scarlet colour. Lavoisier has shewn that a man consumes, in the space of 24 hours, not less than 32 ounces, troy, of Oxygen Gas. Effect upon colours. The liquor made from Whelk, upon exposure to atmospheric air is admitted, they begin to germinate. Hence the wellknown fact, that seeds will not germinate if placed at too great a depth below the earth's surface. The experiments of Sheele, Gouch, Archand, &c. fully prove that seeds will not germinate unless oxygen be present, and that it is not atmospheric air, but the Oxygen it contains, which is necessary to the process, for seeds will not germinate in either azote, carbonic acid, or hydrogen gas. Dr. Humbolt found that seeds which do not commonly germinate in our climate, even in our hot-houses, were capable of germinating after a few days immersion in weak oxymuriate acid. Oxygen combines with all the known metals, with every combustible substance, and with the greater number of substances of which the animal and vegetable kingdoms consist. When by this combination they become oxydes, they are said to be oxydized; when converted into acids, oxyginized. When speaking of atmospheric air, I shall say more on this important subject. (To be continued.) [We shall feel ourselves obliged if STUDIOSUS will forward the continuation of his Essays as soon as possible, that our arrangebeg all our other Correspondents, whose artiments may not be thrown into disorder. We cles are announced to be continued, to take this hint.] EDITOR. ON BALLOONS. tion, by furnishing a supply of heated air, in the room of that which is gradually condensed by cooling. It is ascertained from experiment, that the rarity of the air in these machines deMa-pends solely on its heat, and its property of cooling slowly. This Balloon is raised or lowered, while in the atmosphere, by increasing or diminishing the fire. MR. EDITOR. SIR,-If you think the following plain and easy observations on Air Balloons worthy a place in your excellent gazine, they are at your service. I remain, your's, &c. J. K -M. Small Balloons, of thin paper, raised on this principle by the flame of a sponge, or ball of cotton, dipped in spirits of wine, have been exhibited in every part of Europe. The Hydrogen Gas Balloon is preferable to the other, in the present early state of our knowledge. It is usually formed of thin silk varnished over. When filled with gas, its tubc of communication is usually closed, so that the air cannot escape. The adventurers are placed in a car, or small vessel, attached to the Balloon by strings, proceeding from a net which covers its upper part. They carry bags of sand with them to serve as ballast, and the end of the tube of communication, as well as a string, that by pulling, may open a valve in the top of the Balloon, are continued down into the car; by these means they have, for a limited time, the power of ascending or descending at pleasure: for the power of ascension is increased by emptying one or more sand bags, or diminished by suffering the gas to escape, either by the tube or through the valve. It may be ob THE Air Balloon is of two kinds; the one intended to contain heated air, the other inflammable. Hot air occupies more space when colder; and inflammable is much lighter at a given temperature, than the common air of the atmosphere. From this, it follows that any mass of either heated or inflammable air, if at liberty, will ascend in the atmosphere with a force of buoyancy equal to the difference between its own weight, and the weight of an equal bulk of common air. If the heated or inflammable air be included in a bag, and the weight of the bag be less than the difference just mentioned, the bag will be carried upwards, though with a less degree of force, namely, with a force equal to the difference lessened to the weight of the bag. This is commonly called an Air Balloon; which, though its figure is not essential to its property of ascending, we will suppose to be a globe. If the magnitude of a Balloon be increased, its power of ascension, or the difference between the weight of the included air, and an equal bulk of common air, will be augmented in the same proportion. For its thick-served, that the Hydrogen Gas, on ness being supposed the same, it is as the surface it covers, or only as the square of the diameters. This is the reason why Balloons cannot be made to ascend, if under a given magnitude, with cloth or materials of the same thickness. The first Balloon which was invented, was as follows,-it consisted of an immense bag of canvass, painted with a composition that might lessen its susceptibility to take fire. A net covers the upper part of its surface, from which proceed ropes, that sustain a gallery, to carry the adventurers and fuel. The lower part is affixed to the gallery, and open to receive the streams of heated and rarefied air, produced by means of fire, made in a proper apparatus in the ground; and the attached grate serves only to maintain the requisite degree of rarefac account of its great lightness, will not descend through the tube of communication, unless, either by its own expansion from heat, or by the diminished pressure of the atmosphere at great heights, it is made to escape while the balloon is fully inflated; but it will issue from the upper valve when open. The Hydrogen Gas produced in the large way, by the effusion of diluted sulphuric acid on iron shavings, is rather less than one-fifth of the weight of an equal bulk of atmospherical air. It is estimated that a cubic inch of iron, gives a cubic foot of Hydrogen Gas; and the strong sulphuric acid, sold in London, requires to be diluted by five times its bulk of water for this experiment. (To be continued.) |