The quantity of gold which covers one inch of this wire will be twelve times less than that which covers one foot. Hence, this quantity will be the 8,640,000th part of an ounce. If this inch be again divided into 100 equal parts, every part will be distinctly visible without the aid of microscopes. The gold which covers this small but visible portion is the 864,000,000th part of an ounce. But we may proceed even further; this portion of the wire may be viewed by a microscope which magnifies 500 times, so that the 500th part of it will thus become visible. In this manner, therefore, an ounce of gold may be divided into 432,000,000,000 visible parts, each of which will possess all the characters and qualities found in the largest masses of the metal. It will retain its solidity, texture, and colour; it will resist the same agents, and enter into combination with the same substances. If the gilt wire be dipped in nitric acid, the silver within the coating will be dissolved, but the hollow tube of gold which surrounded it will still cohere and remain suspended. (15.) The organised world offers still more remarkable examples of the inconceivable subtilty of matter. The blood which flows in the veins of animals is not, as it seems, an uniformly red liquid. It consists of flat discs of a red colour, floating in a transparent fluid called _serum_. In different species these discs differ both in figure and in magnitude. In man and all animals which suckle their young, they are perfectly circular or nearly so. In birds, reptiles, and fishes, they are of oval form. In the human species, the diameter of these discs is about the 3500th of an inch. Hence it follows, that in a drop of blood which would remain suspended from the point of a fine needle, there must be about 3,000,000 of such discs.