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tains a rexio, and a substance peculiar to bile, bamed piaromet, #whitila kolid substance formed into globules, with water and salis, chiefly phosphate of lime, muriate, sulplate, and phosphate of soun.

Definition 1. When mie chemical substance decom. poses another. It is called a chemical tout,

2.- Il salt be mixed in water, it is said to be in Wition, and the water is called the menstruuin. :)

3.--Il no more sult will dimulve, the water is said, so be saturated,

4.-II' we would extract the salt, we must evaporate the water by hrat, with a still, or retort, or aloubit, and if the varour from either of these pass through a splne! tube or worni, to the receiver, we shall have distud water, and the residuum of sale will remala in the will

5. Solid substances are reduced into powdent My tri turation, pulverization, and levigation; brittle substances are pulverized by meaus of linnmers, pescles and mat. tara, stones and mullore,

0.-The separation of the Aper parts or bodies from the coarser is performed by means of sing or reasons

7.-- Filtration is a faer species of 'Think, performed through the pores of paper, dannel, Ant linen, vand, &r. It is used only for separating Buldu froin polide.

8.- Fusion, or the melting of a solid body, by the action or heat, requires, according to their several naturen, triva cibles of diferent kinds strong enough to resist the pres made of curthenware, porcelain, or a nixture of clay and powder of black lead, or of black-tead altogether,

9, Sounctimes crucibles have covers made of Carthicowate, but in other cases the fused metal must be erponed tv a current of air, for this purpose the crucibles are broad and shallow, and are called ćupris.

10.- Blow.piprs are med for directing the fame of candle or lamp against any piece of ore or other substance required to be examined and when the mod mdr Mle Chirs are used lustead of common alr, tito heat tr molt powerful

11. The various degrees of heat which are required for the performance of chemical operations, eenderit te Conary ibat the chemist nirould also be pomersed aldur 416,- Soe Grammar of Philosophy.

XXII. Electricity and Galvantsm. 534. If a piece of glass, or sealing-wax, be rubbed on a piece of dry woollen cloth, or silk, and instantly held over any light substances, they will be attracted towards it, raised on an end, and otherwise put in motion.

The power thus excited is called electric; and if the experiment be made in the dark, the glass and the wax will exhibit faint signs of light; which light is called the dectric fire or Suid.

535. If the glass be of larger dimensions, and surned rapidly round by a winch and a wheel, instead of being rubbed backward and forward with the hand, and be provided with a piece of silk to rub against it during its rotation, streams and large sparks of Auid fire will be elicited, which will fly round the glsss, attract light bodies, and produce a pungent sensation.

Obs. 1.-By attracting light bodies, it is meant, that light bodies move towards the electrified body; but it is to be presumed, that that which is called attraction, is in truth some impulse from without or beyond the light body. The mechanical action of attraction supposed to exist between distant bodies, seems to be an absurdity, and ought to be expunged from science. The term repulsion is even more absurd than attraction.

2.Sir Richard Phillips in his Essays, page 92, proposcs to substitute for the active verbs attract aud repel, the passive ones accide and discede ; and their nouns acci. rion and discession, as implying the mere facts of going to. gether and separating.

536. This glass, its cushion of silk, wheel, &c. are called an electrical machine. The fluid,

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or power produced by it, is one of the most wouderluh in nature.

It is found, that it will pass along some on dies, and not along others, that it may be re. ceived and diffused by sharp points; that a superabundance of it, in one place, acts as a repellant in the parts iuimediately adjoining : and that it has a constant and violent tendency to restore its own equilibrium in all bodies

THE ELECTRICAL MACHINR
Prime Conductor, Glan Cylinder

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637. The bodies, over which it passes freely are all animals, most animal and vegetable substances, water, &c.; all which are called con-' duetons of electricity,

But it will not pass over glass, sulphur, charcoal, will, baked woods, or dry woollen sub. alaseos; nor through air, except by foree, in sparks, to short distances.

All these bodies, therefore, are called non conductors.

838. The power of exciting it, receiving it on points, and contining it to bodies, over which

it freely passes, by placing these on bodies, over which it will not pass, gives rise to all the paenomena of practical electricity.

llence a metallic conductor, provided with brass-points, und elevated on glass-legs, is placed opposite the revolving glass cylinder, to receive by its points the electric power, which is condeused on the cylinder, but unable to es cape on account of its being surrounded only by air, and supported by glass legs, both which are Non conductors.

630. If the hand, or a metallic knob, be held within three or four inches from this metallio or muin conductor, a large spark will escape, which, in the dark, will be forked, and of the colour of lightning:

There will also be a snapping noise ; which, increased by large quantities, would be likely to produce ihe noise of thunder.

In fact, lig hening and thunder are effects of electricity in the clouds.

A flash of lightning is simply a stream of the electric power passing from the clouds to the earth; from the earth to the clouds; or from one cloud to another cloud ; and thunder is the report, and the echoes of the report, between the clouds and the earth.

010, But the most wonderful effect of the electric fluid, is its power of suddenly con tratting the muscles of animals when it violently passes through them from one place to another, to restore its equilibrium.

It will not pass through glass; il, therefore,

a plate of glass, in the form of a jar, or otherwise, be conted on both sides, with either gold, silver, or tin-foil, and one side be brought into contact with the main conductor, the other side will instantly part with its electricity, and the plate of glass be said to be charged.

041. If one hand be put to the under or outer side of the said charged plate, and the other hand be brought into contact with the other or charged side, the equilibrium of the two sides will be restored through the body; and á violent contraction, or blow of the muscles will be felt, producing a shock peculiar to this operation.

The severity of the shock, is proportioned to the size of the plate or jar. Whey many jars are joined together, and charged in this way, they are called a battery: and some bat. teries have been made so powerful, as to kill an ox, melt gold, and produce all, the surprising plienomena of real lightning,

542. Philosophers amused themselves, for a century, with experiments on the electrical ap. paratus; but a new mode of exciting this power, was discovered by Galvani; and the expo riments made in his way, are called Galvanian.

It is found, that there are two classes of conductors : --perfect, as the metals; and imperfect, an water and the mineral acids: and if these are laid alternately, two perfect and oue imper. fect, or two imperfect and one perfect, the two ends or sides, will constantly produce an electric shock.

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