of the forms of organized life ultimately decay, and are resolved into inorganic aggregates; and the same elementary substances, differently arranged, are contained in the inert soil, or bloom, and emit fragrance In the flower; or become, in animals, the active organs of mind and intelligence. An artificial operations, changes of the same order occur: substances having the characters of earth, are converted into metals; clays and sands are united, so as to become porcelein; earths and alkalies are combined into glass; acrid and corrosive bodies are formed from tasteless substances; coJours are fixed upon stuff's, or changed, or made to disappear; and the productions of the mineral, vegetable, and animal kingdums, are converted into new forins, and made subservient to the purposes of civilized life. To trace, in detail, these diversified and complicated phæ nomena, to arrange them, and deduce general laws from their analogies, is the business of Chemistry."

507. The ancients conceived that there were but four elements, or first principles--Air, Water, Earth, and Fire.

The moderns have analyzed these four elements, and have discovered other elements of those elements, viz. Oxygen, Hydrogen, Nitrogen, Chlorine, Carbon, Caloric, (or atomic motion) Sulphur, Phosphorus, nine Earths, and twenty-eight Metals,

Obs. 1-Atmospheric AIR is now found to be a componad of Nitrogen or diote, and Oxygen, which are preserved in a gaseous state by Calorie,

WATER is found to be a compound of Oryges and Hydrogen:

EARTH is a compound of niue different substances, now called Earths. (See 521.)

And Firr is found to consist of mere atomie motion.

2.-The forms of matter are ell arranged into three distinct classes, by SIR H. DAVY. The first class consists of solid which compose the great known part of the globe. Solid bodies, when in small masses, retain what

ever mechanical form is given to them: their parts are separated with difficulty, and cannot readily be made to unite after separation; some solid bodies yield to pres sure, and do not recover their former figure when the compressing force is removed, and these are called nonelastic solids; others, that regain this form, are called elastic bodies. Solids differ in degrees of hardness; in colour: in degrees of opacity or transparency, in density, or in the weight afforded by equal volumes; and when their forms are regular or crystallized, in the nature of these forms.

The second class consists of Aquids, of which there are much fewer varieties. Liquids, when in small masses, assume the spherical form; their parts possess freedom of motion; they differ in degrees of density and tenacity; in colour and degrees of opacity or transparency. They are usually regarded as incompressible; at least a very great mechanical force is required, to make them occupy space perceptibly smaller.

The third class, elastic fluids or gases, exist free in the atmosphere; but they may be confined by solids, or by solids and fluids, and their properties examined. Their parts are easily moveable; they are compressible and expansible; and their volumes are inversely, as the weights compressing them. All known elastic fluids are transparent, and present only two or three varieties of colour; they differ materially in density

3.-Besides these forms of inatter, which are easily sul mitted to experiment, and the parts of which may be considered as in a state of apparent rest, there are other forcas of matter which are known to us only in their states of motion when acting upon our organs of seuse, or upon. other matter, and which are not susceptible of being confined. They have been sometimes called ethereal substances, which appears a more unexceptionable name than imponderable substances. It cannot be doubted that there is matter in motion in the space between the sun, the stars, and our globe; though it is a subject of dis cussion, whether successions of particles be emitted from these heavenly bodies; or motions communicated by them, to particles in their vicinity, and transmitted by

muccessive impulses to other particles. Eiherval matter difors, either in its unture, or in its affections, from mos tion, for it produces different effecta adiant heat,

and different kinds of light.

SON. CALORIC, say many chemists, is a more name of that element or principle, which, comBixed with various bodies, produces the sensation of heat; but, according to the theory of Sir Richard Phillips, there is no such element, and all the phenomena are mere effects of atomiO

MOTIONS

Obs. 1.Body, says he, is susceptible of two varietias of motion: (1) a motion or impulse of an aggregate, which occasions it to change its place in regard to other Aggregates; and (2) a motion of the atoms of an aggregate, created when any impulse from any cause cannot produce commensurate change of place in the aggregata and diffuse the motion, so that, by re-action, the impulse terminates within the body in the mutual actions of ite component atoms

2.--Motion of both kinds, says Sir R. Phillips, confinues to affect a body, until it has been imparted or transferred to aggregates in contact, or has been diffused or radiated through the medium in which it is impersed i and this law of the equalization of motion, by the contact of moving aggregates and atoms with others susceptible of receiving and diffusing the motion, is the proximate cause of all varieties of material phenomena

3.--Motion appears, therefore, to constitute the life, power, and energy of matter; and is the active soul of the Universe Matter is its patient, and the relative phenomens of bodies are the results. As it acts ou Aggregates by contact, or by impulse, on and through media, it con atitutes the object of Physical Philosophy, and, as it af. fects compounds or structures of Atoms, it is the obices of Chemical Philosophy,

4.When percussion or collision does not produce an equat quantity of aggregate motion in a proportionate ohange of place in the aggregate; or when the motion

received cannot be transferred by diffusion, as when a plece of iron, laid on an anvil, receives the motion of a hammer, or when two pieces of wood are rubbed together, au intestine re-action of the atoms in the iron and wood takes place, accompanied by the perception of heat, und by a series of phenomena depending on the quantity of motion thus concentrated, and on the acceleration of the same by reiterated blows, rubbings, or transfers of motion, 3.This intestine motion produces various phenomena of the several component atoms of the affected body in regard to one another, and to the heterogeneous media in which they are situated: thus, one quantity creates a perception of heat, another sensibly imparts that percep tion to the atoms of the surrounding media, another con warts the fixed mass into fluids, au acceleration converts the feuds luto diverging gas, and a further acceleration, which exceeds the radiating powers of the surrounding media, decomposes those media, exhibiting flame and jutense heat, in the solidification of the oxygenous part of the media, and producing subtle radiations on the rare medium which fills space, thereby affecting the nerves of the eye, imbued with that medium, with the perceptions of light.

6--The parting with each degree of atomic motion produces a contrary series of phenomena: thus gas, on parting with its heat or atomic motion to other bodies, becomes liquid, and liquids, by patting with their heat or excited motion, become solids; and the diffusion of heat or atomic motion on such re-conversion is sensible, when the oxygenous part of atmospheric air, solidified by respiration, gives out what is called animal heat; and when the same, solidified by combustion, or reduced in volume by compression, gives out heat, and excites the pulsations of light. Phillips's Synopsis,

7--When any body (says Sin H Davy) is cooled, occupies a smaller volume than before; it is evident, therefore, that its parts must have approached towards each other; when the body is expanded by heat, it is equally evident that its parts must have separated from each other. The immediate cause of the phenomena of heat, then, is mation, and the laws of its communication

are precisely the same as all the laws of the communication of motion.

Since all matter also may be made to occupy a smaller volume by cooling, it is evident that the particles of matter must have space between them; and since every body can communicate the power of expansion to s body of a lower temperature, that is, can give an expan sive motion to its particles, it is a probable inference that its own particles are possessed of motion; but, as there is no change in the position of its parts as long as its tem perature is uniform, the motion, if it exist, must be a vibratory or undulatory motion, or a motion of the particles round their axís, or a motion of particles round each other.

It is possible to account for the phenomena of heat, if it be supposed that in solids the particles are in a constant state of vibratory motion, the particles of the hottest bodies moving with the greatest velocity, and through the greatest space; that in fluids, and elastic fluids, besides the vibratory motion, which must be conceived greatest in the last, the particles have a motion round their own axis, with different velocities, the particles of elastic fluids moving with the greatest quickness; and that, m ethereal substances the particles move round heir own axis, and separate from each other, penetrating n right lines through space.

Temperature may therefore be conceived to depend upon the velocities of the vibrations; increase of capacity on the motion being performed in greater space; and the diminution of temperature during the conversion of solids into liquids or gases, may be explained on the principle of the loss of vibratory motion, in consequence of the revolution of particles round their axis, at the moment when the body becomes fluid or æriform, or from the loss of rapidity of vibration in consequence of the notion of the particles, Dary's Chemistry;

8.-In fine, says Sir R. Phillips, Motions of matter subject to regular mechanical laws, acting absolutely or subordinately, generally or locally, on aggregates og stoms, and producing various densities and different de trees of locomotion and affinity in atoms of matter of different constituent forms, are the proximate causes of all