Elementary co-relation is conspicuous in the opposite polarities of the loadstone, magnet, and crystals, and all bodies subject to polarization, which includes the animal frame. Similar co-relation is evinced between the galvanic fluids, those of the pile, and those named electricity; likewise between oxygen and hydrogen, the oxygenating element and nitrogen, acids and alkalies and all mutually neutralizing substances. Still it is not meant that all the general elements are so paired; doubtless, there are several ratios of size between the atoms of the different elements, for the purpose of multiplying variety among formations, the substance of which is of the same species throughout. Possibly the correlative principle gave rise to the ideal scale of _chymical affinities_, subsequently refined to _affections of matter_. Naturally, correlative elements will be found together, as are nitrogen and the imponderable element; also the magnetic fluids common to iron. MAGNETISM. Were attraction a property of the atomic substance of the loadstone, it could be neither transferable, receivable, nor liable to be destroyed by fire. A magnet is a work of art, the substance is inert, it can no more attract than think. Magnetism is an accident of matter; it consists in the correlatives of an iron bar having become separated, and drawn one to each end of the bar: separation and transition to the extremities of the bar, are what the rubbing on the poles of the loadstone effects. Two paving-stones hanging a short distance asunder and touched by nothing but the tranquil air, remain at rest; but should attract each other had "every atom in creation" the property. Were a vacuum, partial vacuum or air much rarer than atmospheric, now placed between the suspended stones, each would be in motion towards the other the same instant. Here both _causes_, the general pressure, and the minus-pressure, or motion _promoting_ means, are given; the latter are sensibly present, and the absence of attraction is as evident as the inutility of anything of the kind to effect the mutual approach of the two bodies. Not so is the approach of two magnets understood, because the intermediate minus-pressure means _present_ are not sensible. That iron magnets do not move together by attraction, or that attraction is not the cause of the phenomena imputed to it, is proved in the case of iron-filings dropping from a bar, when the connection of the bar with the galvanic battery is broken; and it will not be contended that the galvanic current is attraction.