Слике страница
PDF
ePub

$

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 aggregete and diffuse the motion, so that, by re-action, the impulse terminates within the body in the mutual actions of its component atoms.

2.--Motion of both kinds, says Sir R. Phillips, continues to affect a body, until it has been imparted or transferred to ago gregates in contact, or has been diffused or radiated through the medium in which it is immersed; and this law of the equalization of motior, 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 phenomena of bodies are the results. As it acts on Aggregates by contact, or by impulse, on and through media, it constitutes the object of Physical Philosophy; and, as it affects compounds or structures of Atoms, it is the object of Chemical Philosophy.

4.-When percussion or collision does not produce an equal quantity of aggregate motion in a proportionate change of place in the aggregate ; or when the motion received cannot be transferred by diffusion, as when a piece of iron, laid on an anvil, receives the notion of a hammer, or when two pieces of wood are rubbed together, an intestine re-action of the atoms in the iron and wood takes place, accompanied by the perception of heat, and 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.

5. 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 perception to the atoms of the surrounding media, another converts the fixed mass into fuids, an acceleration converts the fluids into diverging gas, and a further acceleration, which exceeds the radiating powers of the surrounding media, recomposes those media, exhibiting flame and intense 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 parting with their beat or excited motion, become solids; and the diffusion of heat or atomic motion on such reconversion 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 Sir H. DAVY) is cooled, it occu. pies a smallır 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 motion, 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 a body of a lower temperature, that is, can give an expansive 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 temperature is uniform, the motion, if it exist, must be a vibratory or undulatory motion, or a motion of the particles round their axis, 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, in ethereal substances the particles move round their own axis, and separate from each other, penetrating in 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

found their axis, at the moment when the body becomes fluid or æriform, or from the loss of rapidity of vibration in consequence of the motion of the particles. Davy's Chemistry.

8. In fine, says Sır R. Phillips, Motions of matter subject to regular mechanical laws, acting absolutely or subordinately, generally or locally, on aggregates or atoms, and producing various densities and different degrees of locomotion and affinity in atoms of matter of different constituent forms, are the proximate causes of all phenomena ; and, as one series of phenomena depends on another, so all existing phenomena are, in regard to others, physically fit, compatible, and harmonious : and, as matter cannot originate its own motion, so, in considering motion as the proximate cause of all phenomena, we arrive, through the ascending series, at the sublime FIRST CAUSE of motion and all phenomena.

518. CARBON is the base of almost all vegetable and animal substances. Charcoal is impure carbon ; and diamond is pure carbon, except a small portion of oxygen with which it has been found to be combined. When combined with oxygen, it forms carbonic oxyde and carbonic acid gas.

Obs.-Carbon exists in large quantities in chalk, lime, stone, &c. From these it is procured in the form of gas, by adding sulphuric acid in a certain apparatus, and sold under the name of aerated or soda water, which is merely water impregnated with carbonic acid gas. Carbonic acid gas is the choke-damp of mines. Oils, fats, &c. are compounds of Carbon and hydrogen.

519. OXYGEN is an element or simple substance diffused generally through nature ; and its different combinations are essential to animal life and combustion.

Combined with caloric, it becomes oxygen gas: 100 parts of atmospheric air contain 28 parts of oxygen gas; and 100 parts water consists of 85 oxygen and 15 nitrogen.

Obs. Oxygen gas is distinguished from all other gaseous matter by several important properties. Inflammable substances burn in it under the same circumstances as in common air, but with infinitely greater vividness. If a taper, the flame of which has been extinguished, the wick only remaining ignited, be plunged into a bottle filled with it, the flame will be instantly rekindled, and will be very brilliant, and accompanied by a crackling noise. If a steel wire, or

thin file, having a sharp point, armed with a bit of wood in combustion, be introduced into a jar filled with the gas, the steel will take fire, and its combustion will continue to produce a most brilliant phenomenon.

2. Oxygen gas is respirable; a small animal, confined in a jar filled with this gas, lives four or five times as long as in an tequal quantity of common air;-hence, it has been

called vital air.

520. During the burning of any combustible body, the oxygen leaves the atmospheric air, and combines with the calx or residuum, adding to its weight, and forming what is called an oxyde or an acid.

Obs. 1.--This process is called oxygenation ; and if oxy. gen be combined with sulphur, phosphorus, carbon, or any other substance in various degrees, it will produce oxydes or acids of strength proportioned to the degree of oxygenation; which are distinguished by the terminations ous and ic; thus in regard to sulphur and phosphorus, we vary, 1. Oxyde of sulphur; 1. Oxyde of phosphorus; 2. Sulphurous acid;

2. Phosphorous acid; 3. Sulphuric acid,

3. Phosphoric acid; 2. Combined with metals in various degrees, oxygen pro, duces oxydes of different colours; as grey oxyde of lead, red oxyde of lead, &c.

521. HYDROGEN is one of the most abundant principles in nature; and 15 parts of it combined with 85 of oxygen, form water.

It is only to be met with in the gaseous form; and, being twelve times lighter than atmospheric air, is employed to fill balloons.

It is also inflammable, and is the gas called the fire-damp, so often fatal to miners. It is the chief constituent of oils, fats, spirits, ether, coals, and bitumen.

Obs.--Hydrogen is always produced from water, and WATER is formed by the union of oxygen with HYDROGEN. Its existence in water is manifested by water in a state of vapour being made to pass over iron wire made red-hot, the vgen of the water then combines with the iron, the

r disappearing, and the hydrogen gas remains.

The process for filling balloons, is by mixing five parts of water with one of sulphuric acid; and, by pouring the mixture on iron filings, the light gas, by the decomposition of the water, will rise into the balloon; and the balloon, being. 12 times lighter than the atmospheric air, will rise through it.

3. Carburetted Hydrogen gas is now very extensively used in lighting the streets of London and other towns. It is distilled from coals, and purified by passing through lime-water. It is then conveyed into a reservoir, called a Gazometer, and from thence through pipes, to light streets, houses, churches, theatres, and shops.

AIR-BALLOON

[graphic][ocr errors]

522. NITROGEN, or AZOTE, is a substance generally diffused through nature, and particularly found in animal bodies.

Nitrogen is not to be found in a solid or liquid state; but, when combined with caloric, it forms azotic gas, in which no animal can breathe, or any combustible burn.

Seventy-eight parts combined with 22 parts oxygen, form 100 parts of atmospheric air. In a higher degree of oxygenation, as 30 to seventy, it produces nitrous gas; and still higher, nitric acid.

Obs. 1. -As oxygen is absorbed during burning or bre ing, and as soon as the 22 parts, or nearly, of oxygen are av. sorbed, the remainder is nitrogen, and becomes mephitic, or deadly, being incapable of sustaining life or flame.

« ПретходнаНастави »