then the flame should be blown towards the point in one cafe, and from it in the other.

So the electric fly, as it turns horizontally, recedes from the direction of the points of the tangents, whether it be electrifed with vitreous or refinous electricity; whereas if it was supposed to receive electricity, when electrised by refin, and to part with it when electrifed by glass, it ought to revolve diffe- i rent ways; which also forcibly opposes the theory of pofitive and negative electricity.

As an electrifed point with either kind of electricity causes a stream of air to pass from it in the direction of the point, it seems to affect the air much in the fame manner as the fluid matter of heat affects it; that is, it will not readily pass through it, but will adhere to the particles of air, and is thus carried away with them.

From this it will also appear, that points do not attract electricity, properly speaking, but fuffer it to depart from them; as it is there less attracted to the body which it furrounds, than by any other part of the furface.

And as a point presented to an electrifed conductor facilitates the discharge of it, and blows the flame of a candle towards the conductor, whether vitreous or refinous electricity be accumulated upon it; it follows, that in both cafes fome electric matter paffes from the point to the conductor, and that hence there are two electric ethers; and that they combine or explode when they meet together, and

give out light and heat, and occupy less space in this their combined state, like the union of nitrous gas with oxygen gas.

IV. ACCUMULATION OF ELECTRIC ETHERS BY CONTACT.

The electric ethers may be separately accumulated by contact of conductors with nonconductors, by vicinity of the two ethers, by heat, and by decompofition.

Glafs is believed to confift in part of confolidated refinous ether, and thence to attract an electric atmosphere round it, which confifts of a greater proportion of vitreous ether compared to the quantity of the refinous, as mentioned in Propofition No. 4. This atmosphere may ftand off a line from the furface of the glafs, though its attractive or repulfive power may extend to a much greater diftance; and a more equally mixed electric atmosphere may stand off about the fame diftance from the furface of a cufhion.

Now when a cushion is forcibly preffed upon the furface of a glafs cylinder or plane, the atmosphere of the cushion is forced within that of the glass, and confequently the vitreous part of it is brought within the sphere of the attraction of the refinous ether combined with the glass, and therefore becomes attracted by it in addition to the vitreous part of the fpontaneous atmosphere of the glafs; and the refinous part of the atmosphere of the cufhion is at the fame time

repelled by its vicinity to the combined refinous ether of the glass. From both which circumftances a vitreous ether alone furrounds the part of the glafs on which the cushion is forcibly preffed; which does not, nevertheless, resemble an electrised coated jar; as this accumulation of vitreous ether on one fide of the glass is not fo violently condensed, or fo forcibly attracted to the glass by the loose refinous ether on the other fide of it, as occurs in the charged coated jar,

Hence as weak differences of the kinds or quantities of electricity do not very rapidly change place if the cushion be suddenly withdrawn, with or without friction, I fuppofe an accumulation of vitreous electric ether will be left on the surface of the glass, which will diffuse itself on an infulated conductor by the affiftance of points, or will gradually be difsipated in the air, probably like odours by the repulfion of its own particles, or may be conducted away by the surrounding air as it is repelled from it, or by the moisture or other impurities of the atmosphere, And hence I do not fuppofe the friction of the glassglobe to be neceffary, except for the purpose of more eafily removing the parts of the furface from the preffure of the cushion to the points of the prime conductor, and to bring them more eafily into reciprocal contact,

When fealing wax or fulphur is rubbed by a cushion, exactly the fame circumftance occurs, but with the different ethers; as the refinous ether of

the fpontaneous atmosphere of the cushion, when it is preffed within the spontaneous atmosphere of the fealing wax, is attracted by the folid vitreous ether which is combined with it; and at the fame time the vitreous ether of the cushion is repelled by it; and hence an atmosphere of refinous ether alone exifts between the fealing wax and the cushion thus preffed together. It is nevertheless poffible, that friction on both fealing wax and glass may add fome facility to the accumulations of their oppofite ethers by the warmth which it occafions. As most electric machines fucceed beft after being warmed, I think even in dry frofty feafons.

Though when a cushion is applied to a smooth furfaced glass, fo as to intermix their electric atmofpheres, the vitreous ether of the cushion is attracted by the refinous ether combined with the glass; but does not intermix with it, but only adheres to it: and as the glafs turns round the vitreous electric atmosphere ftands on the folid refinous electric ether combined with the glafs; and is taken away by the metallic points of the prime conductor.

Yet if the furface of the glafs be roughened by fcratching it with a diamond or with hard fand, a new event occurs; which is, that the vitreous ether attracted from the cushion by the refinous ether conbined with the glafs becomes adhesive to it; and ftands upon the roughened glafs, and will not quit the glafs to go to the prime conductor; whence the furface of the glafs having a vitreous electric atmo

fphere, united, as it were, to its inequalities, becomes fimilar to refin; and will now attract refinous electric ether, like a ftick of fealing wax, without combining with it. Whence this curious and otherwise unintelligible phenomenon, that smooth furfaced glafs will give vitreous electric ether to an infulated conductor, and glass with a roughened furface will give refinous ether to it.

V. ACCUMULATION OF ELECTRIC ETHERS BY VICINITY.

Though the contact of a cushion on the whirling glass is the easiest method yet in use for the accumulation of the vitreous electric ether on an infulated conductor; yet there are other methods of effecting this, as by the vicinity of the two electric ethers with a nonconductor between them.

Thus I believe a great quantity of both vitreous and refinous electric ether may be accumulated in the following manner. Lét a glass jar be coated within in the usual manner; but let it have a loose external coating, which can easily be withdrawn by an infulating handle. Then charge the jar, as highly as it may be, by throwing into it vitreous electric ether; and in this ftate hermetically seal it, if practicable, otherwise close it with a glass stopple and

wax.

When the external coating is drawn off by an infulating handle, having previously had a communication with the earth, it will poffefs an accumulation of refinous electric ether; and then touching