415. Electricity, as an aerial function, is terrestrial heat. Both are therefore conducted by the same rigid linear bodies and isolated by the same. The isolation of electricity coalesces with absence of form, or with the transition of denser bodies into air.
416. Electricity is an antagonism between air on the one side and water and earth upon the other. By these therefore two kinds of operation are posited in the air.
417. While electricity is the tension of air with the other elements, it is also the tension of the principles themselves of air. Electricity is a twofold character appertaining to the two principles of air. The tension of æther and of substance, thus the tension of fire repeated upon the two elementary bodies of air, is electricity. Electricity exists under two forms, as the electricity of the substance or body of fire, and as that of the planet. These two conditions are perhaps incorrectly named + E and-E, or positive and negative electricity.
418. The + E is the more energetic, active in itself, polar; it is the electricity of fire represented in oxygen. The-E is the weaker, that which has only been evoked, the basic; it is the electricity of the planet represented in nitrogen, hydrogen, carbon, sulphur. It may be said that-E is related to + E as planet is to sun, as periphery to centre. The sun is + E, the planet-E, the one the electricity of oxygen, the other of hydrogen.
419. These electrical conditions must always be changing in the air, according as the slightest influence is brought to bear upon them from without. The air consists in this change of electrical poles. Were the poles not to change, the air would be a solid element. The earth is an air with _fixed_ electricity, the water with extinguished or neutralized electricity.
420. The twofold character of the aerial principles is increased by every polarizing action from without, and therefore principally by the surface of the earth, which consists of two elements. Were there no surface to the earth, were simply air present, then there would be no electrical change of poles. The surface of the earth itself, however, produces no change of poles in the air, for it remains always neutral; but it becomes unequal or polar from the change wrought upon it by water and earth, by light, by heating and by chemical processes.