That electricity, on the other hand, does not act in length merely, is clear, from the fact that every electric body is electric over its whole surface. But that electricity acts both in length and breadth, and _only_ in length and breadth, and not in depth; in short, that the (so-called) electrical fluid in an electrified body spreads over the whole surface of that body without penetrating it, or tending _ad intra_, may be proved by direct experiment. Take a cylinder of wood, and bore an indefinite number of holes in it, each of them four lines in depth and four in diameter. Electrify this cylinder, and present to its superficies a small square of gold-leaf, held to it by an insulating needle of gum lac, and bring this square to an electrometer of great sensibility. The electrometer will instantly show an electricity in the gold-leaf, similar to that of the cylinder which had been brought into contact with it. The square of gold-leaf having thus been discharged of its electricity, put it carefully into one of the holes of the cylinder, _so_, namely, that it shall touch only the bottom of the hole, and present it again to the electrometer. It will be then found that the electrometer will exhibit no signs of electricity whatsoever. From this it follows, that the electricity which had been communicated to the cylinder had confined itself to the _surface_. If the time and the limit prescribed would admit, we could multiply experiments, all tending to prove the same law; but we must be content with the barely sufficient. But that the _chemical process_ acts in _depth_, and first, therefore, _realizes_ and integrates the fluxional power of magnetism and electricity, is involved in the _term_ composition; and this will become still more convincing when we have learnt to regard _decomposition_ as a mere co-relative, _i.e._ as decomposition relatively to the body decomposed, but composition _actually_ and in respect of the substances, _into_ which it was decomposed. The alteration in the specific gravity of metals in their chemical amalgams, interesting as the fact is in all points, is _decisive_ in the present; for gravity is the sole _inward_ of inorganic bodies—it _constitutes_ their depth.