As matter now exists, not only its ultimate atoms, but even its constituent molecules, are as inconceivably minute, as its aggregations are vast. Taking an exemplification, from organic matter, we find that a single drop of a strong solution of indigo, in which at least 500,000 parts are rendered distinctly visible by the microscope, colors 1,000 cubic inches of water, and as this quantity of water is at least half a million of times greater than the drop of indigo solution, the particles of indigo must be smaller than 2,500,000,000,000, the twenty-five hundred millionth part of a cubic inch. If we dissolve a particle of silver, of 0.01 of a cubic _line_, in size, in nitric acid, it will render distinctly milky 500 cubic inches of a clear solution of common salt; and, consequently, the magnitude of each particle of silver thus divided and diffused, must be somewhat less than the billionth part of a cubic _line!_ So great a number as a billion being but imperfectly conceivable, it may render the idea of this minute division more distinct, by stating that to count a single billion of seconds, by a watch, every day and night without ceasing, would require 31,675 years. In gilding silver wire, it is found, by calculation, that a grain of gold is spread over 1,400 square inches; and as, when examined by a microscope, the gold upon the thousandth part of a linear inch is distinctly visible, it is demonstrated that gold may be divided into particles of at least the billionth, 400 millionth, of a square inch in size, and retain the color and all other characteristics of a California prize. If a grain of copper be dissolved in nitric acid, and then in water of ammonia, it will give a decidedly violet color to 392 cubic inches of water; and, therefore, if there was but one particle of copper in each portion of the water of the size of a grain of sand, of which one million make a cubic inch, it would show that the original grain of copper had become divided into 392 particles. This extreme tenuity of matter, however, is far surpassed in some examples which may be adduced from organic sources. It is upon authentic record that an Irish girl has spun linen yarn, of which one pound was 1,432 English miles in length, and of which, therefore, 17 pounds and 13 ounces would have girt this world; and yet less than the 127 millionth part of this thread would have been distinctly visible, and must have contained other filaments still finer, each of which must have been composed of an indefinite number of smaller particles, themselves, in all probability of complex organization, and containing certainly, minuter atoms of carbon, besides those of gaseous matter.