The heating of a pound of water by one degree has its exact mechanical equivalent;[13] and a given store of elevated temperature will overcome the same weights, whether applied directly to lift them, or turned first into a thermo-electric current, so as to perform its task by deputy.[14] The inference drawn from the phenomena of which these are samples is no less than this: that each kind of force is convertible into any other, and undergoes neither gain nor loss upon the way; so that the sum-total remains for ever the same, and is only differently represented as the proportions change amongst the different forms of life, and between the organic and the inorganic realms. Hence arises the argument that, in having _any_ force, you have virtually _all_; and that, assuming only material atoms as depositories of mechanical resistance and momentum, you can supply a universe with an exhaustive cosmogony, and dispense with the presence of Mind, except as one of its phenomena. [Footnote 13: Viz., the fall of 772 lbs. through a foot. See Mr. Joule's Experiments in Grove's Correlation of Physical Forces, p. 34, 5th ed.] [Footnote 14: See Grove's Correlation, p. 255, 5th ed.] To test this argument, let us grant the data which are demanded, and imagine the primordial space charged with matter, in molecules or in masses, in motion or rest, as you may prefer. Put it under the law of gravitation, and invest it with what varieties you please of density and form. Thus constituted, it perfectly fulfils all the conditions you have asked; it presses, it moves, it propagates and distributes impulse, is liable to acceleration and retardation, and exhibits all the phenomena with which any treatise on Mechanics can properly deal. In order, however, to keep the problem clear within its limits, let us have it in the simplest form, and conceive the atoms to be all of _gold_; then, I would fain learn by what step the hypothesis proposes to effect its passage to the _chemical_ forces and their innumerable results. _Heat_ it may manage to reach by the friction and compression of the materials at its disposal; and its metal universe may thus have its solid, liquid, and gaseous provinces; but, beyond these varieties, its homogeneous particles cannot advance the history one hair's breadth through an eternity. It is not true, then, that the conditions which give the first type of force suffice to promote it to the second; and in order to start the world on its chemical career, you must enlarge its capital and present it with an outfit of _heterogeneous_ constituents. Try, therefore, the effect of such a gift; fling into the pre-existing caldron the whole list of recognized elementary substances, and give leave to their affinities to work: we immediately gain an immense accession to our materials for the architecture and resources for the changes of the world,--the water and the air, the salts of the ocean, and the earthy or rocky compounds that compose the crust of the globe,