5. Hence the nonconductors of electricity are of two kinds; such as are combined with vitreous ether, as resin, and sulphur; and such as are combined with resinous ether, as glass, air, silk. But both these kinds of nonconductors are impervious to either of the electric ethers; as those ethers being already combined with other bodies will not unite with each other, or be removed from their situations by each other. Whereas the perfect conducting bodies, as metals, water, charcoal, though surrounded with electric atmospheres, as they have neither of the electric ethers combined with them, suffer them to permeate and pass through them, whether separately or in their neutral state of reciprocal combination. But it is probable, that imperfect conductors may possess more or less of either the vitreous or resinous ether combined with them, since their natural atmospheres are dissimilar as mentioned below; and that this makes them more or less imperfect conductors. 6. Those bodies which are perfect conductors, have probably neutral electric atmospheres gravitating round them consisting of an equal or saturated mixture of the two electric ethers, whereas the atmospheres round the nonconducting bodies probably consist of an unequal mixture of the electric ethers, as more of the vitreous one round glass, and more of the resinous one round resin; and, it is probable, that these mixed atmospheres, which surround imperfect conducting bodies, consist also of different proportions of the vitreous and resinous ethers, according to their being more or less perfect conductors. These minute degrees of the difference of these electric atmospheres are evinced by Mr. Bennet's Doubler of Electricity, as shown in his work, and are termed by him Adhesive Electric Atmospheres, to distinguish them from those accumulated by art; thus the natural adhesive electricity of silver is more of the vitreous kind compared with that of zinc, which consists of a greater proportion of the resinous; that is, in his language, silver is positive and zinc negative. This experiment I have successfully repeated with Mr. Bennet's Doubler along with Mr. Swanwick. 7. Great accumulation or condensation of the separate electric ethers attract each other so strongly, that they will break a passage through nonconducting bodies, as through a plate of glass, or of air, and will rend bodies which are less perfect conductors, and give out light and heat like the explosion of a train of gunpowder; whence, when a strong electric shock is passed through a quire of paper, a bur, or elevation of the sheets, is seen on both sides of it occasioned by the explosion. Whence trees and stone walls are burst by lightning, and wires are fused, and inflammable bodies burnt, by the heat given out along with the flash of light, which cannot be explained by the mechanic theory.