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the steep, and perished together in the water of Lake Erie. Brigg.

NOTES ON SIR H. DAVY'S EIGHTH LECTURE ON ELECTRO-CHEMISTRY, DUBLIN, NOVEMBER, 1810.

The shades of night were now fast gathering-the wind howled dreadfully-and the angry Lake continued to swell. To find her way through the gloom which hung heavily around, she knew would be impossible, and she therefore determined to remain in her present position until the moon arose, the objects before her gradually faded from her view, yet still she kept her strained eye turned to the point where her beloved Onedia was.

Overcome at length with agitation and intense feeling, she sunk down upon the earth, and endured the killing suspense of an hour's watching, which appeared to her fevered brain an age, until the moon arose. Its light was only partial; heavy clouds rolled around, and intercepted its beams, giving an uncertain view of such things as in any degree became visible. During the long, long hour, she at last heard that her son was alive; but now his voice could no longer be recognized. The slanting light of the moon's pale rays fell upon the tree, but Onedia was no longer to be seen-his seat was vacant-the loved form after which Chia wildly gazed was not met by her searching vision. The distracting conviction pressed upon her, that he was lost! Despair seized her-she rolled on the turf, and called upon him with maniacal frenzy -when again the faint voice of her son met her quick ear;-the cry of "mother" reached her as he called upon her to help him. She sprang from the earth, looked wildly round, and beheld at a short distance from her, her child, struggling to gain the top of the bank. He raised his little hand for her aid-she rushed forward to save him-already had their hands met, when the earth gave way beneath her feet, and the mother and the son were dashed down

142.-VOL. XII.

trary, copper, which dissolves in sulphuric acid, will, on being made highly negative, refuse to act with that acid.

A bar of copper being put into the former solution of silver, after lying undissolved in sulphuric acid, the acid on it precipitated the silver, and the bar was silvered, because the copper was charged negatively. In this manner it would be easy to take dissolved copper from the acid by silver.

Potass and sulphuric acid in their junction cause great heat and effervescence: when the charcoal points of the Voltaic conductors join by their surfaces, they become hot: when they join only at a point, they are not hot, but emit a splendid light. Hence he argued, that heat and light are generated in proportion as there is a diffusion or concentration of combustion.

Copper is positive; sulphur negative. A plate of copper, and a cake of sulphur, make no heat or light, though the electrometer shews a charge; but filings of copper mixed with sulphur, and heated in a retort by a lamp, become luminous as soon as the sulphur melts. Oil of turpentine and aquafortis produce heat and light by their mixture. This should be carefully done under a chimney, in a small quantity, two yards at least from the person who unites them.

Oxymuriate of potass and sugar, makes a chemical action. The vapour is mephitic, but on adding sulphuric acid to the mixture, it blazes with an odoriferous vapour, which corrects the former bad smell.

That heat and light do not proceed from the absorption of oxygen, appears from the sulphur and copper in a shut retort, the neck of which was turned down into water. Sir H. Davy, therefore, supersedes Lavoisier's system, and says, COMBUSTION is generated in the equilibrium of electricity.

Acids contain oxygen, which goes to the positive side of the platina plate, between the conductors, and the base of the acid goes to the negative.

3 м

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Experiment. Acid of phosphorus soon shews a white scum, drawing towards the negative, which burns, being phosphorus renovated. The oxygen goes to the positive, and it is not inflammable.

Phosphorus, in a small retort standing by the neck in a glass vessel, wherein oxygen is generated, becomes gaseous, emitting unequalled splendour: the air left is acid, as proved by wet litmus paper.

The Metals. Metallic oxids, phosphorus, and ammonia, are negative; alkalies were concluded to contain inflammable matter, for the same reason. This suspicion was the origin of Sir H. Davy's discovery. At first he tried a strong solution of potass. It was in vain; it devolved oxygen and nitrogen : next he fused potass, and on the negative charge it appeared inflammable; but as it is a nonconductor when cold and dry, he moistened it with water, and on platina, made negative, he saw some globes of metal on the negative side, some of which burned away; others remained, and, being put into water, reproduced potass after combustion.

One hundred pair of plates in ten minutes made a peppercorn size of potassium. The turmeric paper proves the recomposition of potass, which is not only made in water, but in air, by strong heat.

Sodium requires so much water to make it a conductor, that it loses much by becoming soda the moment after it becomes metal. Sodium swims on water till it effervesces without combustion, and sinks into soda. On the 6th of October, 1807, Sir H. Davy made his potass and sulphur of barytes so heavy, that mineralogists thought it metallic. Lavoisier improved this idea, in supposing lime and other earths were metallic oxids. This led Sir H. Davy from potass and soda to strontites, lime, magnesia, &c. in which he employed an iron wire, and made an alloy of iron, and the metal of these earths, which he could afterwards separate in their reproduction to earth. He tried an amalgam of the earth and mercury, which led Swedish chemists to attempt it, and succeeded in making metal of earth.

Place a globule of mercury in a hole of paste of earth, and the conductor soon makes the mercury take up some of the earth. The mercury is then sublimed from it in a retort with naphtha, and as soon as the naphtha passes over, seal the retort, and place it in 600° Fahrenheit; the remainder of the mercury rises in clouds, leaving behind the metal of the earth. These earths are metallized by the conductor in

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a moist paste, with a continual light, but they recompose the earth as fast as they form the metal. Fifty pair of plates will do it.

From these experiments, Sir H. Davy divides ALL chemical bodies, according to their states at the time, into positive and negative relatively, which in chemistry are always found to unite.

Potasium and sodium may be useful portable forms of pure alkali.

A DISCOURSE ON THE THEORY OF THE PLANETARY SYSTEM.

(By Thomas Cooke, Draycoth, near Derby.) VARIOUS reasons, from time to time, have been assigned, to account for the cause of the planetary motions. Des Cartes supposed that the universe was filled with an ethereal fluid, and that the planets were whirled about the sun in vortices. This system gave way to the doctrines of Sir Isaac Newton, and observations continually prove that the speculations of this great man were correct; but as he only treated of the effects, without explaining the cause, the system of nature cannot yet be considered as completely discovered.

Whether the universe is, or is not, filled with a fluid medium, has much divided the opinions of philosophers. There are two things that tend to throw some light on this subject. The first is, that the fixed stars are suns; that their number, as far as our limited faculties can discover, is incalculable, and that these suns are continually diffusing through space, a medium which produces the sensation of light, or otherwise creating activity in an elastic medium which fills all space, and produces that sensation, by causing vibrations or impres sions on this fluid. Hence it is clear, that space is filled with a fluid substance, and we know not but this fluid may be essential to the phenomena of attraction.

Secondly, it is a well-known axiom, and certainly true, that matter cannot act upon matter when it does not touch it, and when there is no medium between; but that the planets do act upon one another is certainly true, from the observations of the best astronomers. Hence there must be a medium, to cause this action. And as elasticity seems to be essentially necessary to such a medium, we may rationally and fearlessly assert, that the universe is filled with a subtile elastic fluid, by which the planets, &c. are moved.

It has been clearly demonstrated by Sir Isaac Newton, that all matter has a tendency to other portions of matter, and that

17

is tendency or gravitation is inherent in very individual particle. Now, if two odies be placed at a distance in space, urrounded by the elastic medium before mentioned, it will cause a pressure on each f them in proportion to the elasticity of he medium; but this pressure can make O alteration of the medium, its elasticity ausing its density to be the same at all listances from the bodies; hence they could have no tendency to each other. I believe it might also be demonstrated, that o theory can account for the universal endency of matter, but by a continual current of the elastic fluid, flowing from all directions to the bodies, which current can be no ways affected but by allowing the bodies continually to absorb the fluid. I shall, therefore, admit, that all matter, in proportion to its quantity or density, continually absorbs the fluid of the universe; and by this absorption is caused that universal property of matter, termed attrac

tion.

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co-efficients, expressing the distance, will in every case be squared, while the quantity px2 remains unaltered.

In order to comprehend the nature of absorption more clearly, it will be necessary to suppose the universe to be diminished. Therefore, instead of the sun's diameter being nearly 900,000 miles, suppose it to be 1 inch, and the distance of the nearest fixed star cannot be less than 19,400,000,000,000 miles, according to astronomical observations; but as the sun's diameter is taken a little too great, it will be as well to take the round number, 20,000,000,000,000, for the distance of the stars; then by proportion, as 900,000 × 1,760 × 36: 20,000,000,000, 000:

1: 350.7 miles, the proportional distance of the stars; and if we take half this distance for the radius, or the whole for the diameter of the spherical space belonging to the diminished sun or sphere, whose diameter is 1 inch, it will give us an idea of the greatness of the portion of space allotted to so small a quantity of matter, and of the probability of absorption.

It is certain, that this spherical space may be divided into any given number of parts; admit, then, that the number of

And since this current from all directions tends towards the centre of the planetary spheres; and as the quantity of the flowing fluid increases at any distance from the centre above the surface, in proportion to the surface of the sphere whose radius is that distance, the flowing power of the fluid must decrease as the surfaces of the spheres increase, which is as the square of the distance. For if we put x = the diameter of any planet, and p3.1416; then pxxx x=p x2, the surface of the planet; and, at the distance x from the centre, the surface of the sphere is 4px2, the diminished force of the fluid; and if the distance be 3, the surface of the sphere is 9 px, the diminished force at the distance of thrice the radius; and if from these expressions we take the common quantity, we have 1, 4, 9, for the diminution of the force of the fluid, at the distance of 1, 2, and 3 times the radium from the centre. And this is the same as Sir Isaac Newton has demonstrated of the principle of attraction.

That the force will continue to decrease as the square of the distance, is evident, from the consideration that the numeral

may not be greater than a common mite; also, any given quantity of matter may be divided into as many equal parts as the spherical space. Therefore, suppose that, in every division of this space, a particle of this divided matter is placed; and suppose that each of these particles, instead of being spherical, is made long, after the manner of hairs or fibres, each being longer than the diameter of its space, and of an elastic nature; by means of which, they will form a united whole; or an elastic fluid filling the space.

Let n the number of years since the creation of the world, and p= the number of parts into which the sphere, whose diameter is 1 inch, or solidity 5236, may be divided, such that one of them may not sensibly augment the sphere if added to matter to be converted into the elastic fluid; it. Also let x be the given quantity of and let it be of such a magnitude, that ⚫5236 5236. or x = ; now, admit that a quantity of matter, equal to that of the whole sphere or diminished sun, is, after the manner before mentioned, converted into a fluid medium, and diffused over its proper space; then it is evident that a quantity of fluid, equal to that made of the quantity of matter represented by x, may have been absorbed every year since

nx=

n p

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according to the law of John Kepler, who discovered that the squares of the periodical times of the planets, are as the cubes of their mean distances from the sun. Hence, their velocities must decrease the farther they are from the sun; and the velocity of Mercury in its orbit is many times that of the sun; yet, evidently, according to the foregoing rule, it ought to be less. But, from the appearance, termed the zodiacal light, it is very evident that the sun is surrounded by a dense atmosphere, which extends to a great distance from him; for this light extends farther than the orbit of Venus. Now, this dense and extensive atmosphere, like mighty oars, will dash upon the fluid of the universe, and whirl it with a much greater velocity than could be effected by the sun alone; and though the velocities of the planets decrease the farther they are from the sun, yet it is sufficiently evident, that the force by which they are moved must increase to a great distance from the sun; for it must be considered, that the sun and its atmosphere revolve together as one body. Hence, at the distance of one radius from the surface, the force will be twice as great; at twice that distance it will be three times as great as at the surface; and it will probably continue to increase in this way to as many distances of the radius, until the atmosphere gets too rare to carry on in this proportion. Therefore, it is clear that the sun, together with its atmosphere, is quite sufficient to give motion to the planets of the solar system.

I have hitherto only mentioned the motion of the planets as caused by the action of one force, which would cause them to revolve about the sun in circular orbits; but if we consider that they have a tendency toward the sun, it is obvious that the union of these two forces will cause them to make their revolutions in elliptical orbits, having the sun in one of their foci.

This would be the way that the orbits of the planets would be generated, provided that the increments were taken infinitely little, in which case the number of points of the curve would be infinite, and the lines uniting them, would be the diagonals of rectangular parallelograms; for though it must be observed that the whirling force would generate a circular curve, yet if this be diminished sine limite, it will coincide with the tangent; hence the increments would be rectilineal.

What is said of the orbits of the planets, may be said of the satellites, or moons attending them also. By the foregoing observations, every planet has a current of the elastic fluid of the universe continually

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flowing toward its centre, as well as the sun; and as they have a rotary, or diurnal motion about their axis, it follows, that they must have both a flowing and a whirling force. Hence, if any number of smaller bodies or planets be placed at proper distances from one of the primary planets, and from one another, and over its equator, or near thereto, they will be whirled round it, in orbits of an elliptical figure, in the same manner as the primary planets make revolutions round the sun, and will be carried along with it as it proceeds in its orbit. In this way, I suppose the moon to be whirled round the earth; the four satellites, or moons of Jupiter, to be whirled round Jupiter; the seven moons of Saturn, and the six moons of the Georgium Sidus, to be whirled about them, and to be carried along with them as they make their revolutions round the sun.

If other bodies, much smaller than the sun, be placed at an immense distance from him, so that they may be farther from being over his equator than the planets are; in this situation the whirling force of the sun will be much less than if they were placed over his equator. Hence, the flowing force will cause them to descend toward the centre of the sun with an amazing velocity, while the other force will cause them to describe curves of an elliptical figure, having the sun in one of their foci; and, on account of the great disproportion between the two forces, the orbits will be much more eccentric than those of the planets. In this way, I suppose those wonderful bodies, which we call comets, to perform their revolutions round the sun.

The reader may illustrate the motions of the comets by a diagram; in which it must be observed, that the increments generated by the whirling force, must be taken much less than those of the planets. It may also be observed, that the variation will be in proportion to the cosine of the distance from the sun's equator; but as the flowing force continually tends toward the centre of the sun, this rule will vary as it descends toward the sun. And if a comet revolves about the sun's equator, it must either be projected perpendicularly toward the sun, from the higher apsis; or in a tangent from the lower apsis.

My reasons for adopting the above theory, are, 1. All the planets make their revolutions in one direction, from west to east. 2d. They move the same way as the sun does. 3d. They revolve in the plane of his equator, or nearly so. 4th. The satellites perform their revolutions