Minus-pressure means exist in other than the elementary form, as in blotting-paper, candle-wick, pledgets of lint. Within the cupping-glass, which is empty of air only, it is the minus-pressure matter obtained from flame which promotes the rise of blister. Within the vessels of the vascular system, as mucilaginous lining, minus-pressure matter assists the circulation of fluids, on the foregoing capillary principle. The slime on deep-water fish, seems provided to lessen the pressure of the water on the inhabitants of those seas. Minus-pressure matter on one side only of a body, destroys the equilibrium, and promotes the motion of the body; and generally, the partial action, implied by motion, of the medium of space on bodies or their parts, is promoted by interposed minus-pressure matter in every instance of physical change. Only in minus-pressure means, which serve as a partial vacuum in some cases, to disturb the equilibrium of pressure, is motion, or change of place of the elements of bodies, or of bodies themselves promoted: without such means there is nothing to promote the blowing of a wind, or to put the medium of space into action. Cause being given, the _General Pressure_ in the production of every physical effect, the sole province of philosophy consists in tracing out the minus-pressure means which promote the occasional and partial action of the medium of pressure. FIRE. Fire is not hot, although it burns the flesh and promotes pain. Matter, which is unalterable, cannot be made hot or cold, neither is there anything to make it so. If a limb be made rigid, or the nerves of sensation be removed, or the function of the nervous fluid be obstructed, the limb may be burned off unconsciously. Heat is a sensation effected through excitement of the brain; out of the brain there is neither excitement nor heat. The fire does not excite the brain, but the nervous fluid; and although the sensation is not hot, it is imagined that the cause must be hot, which is false reasoning. The chymist finds heat creviced in all things, even those which he admits are destroyed by heat--gunpowder and ice. How can flame be hot, when just obtained from the gases of decomposed ice water? or, if hot, _sui generis_, it must have been hot frozen flame in the original ice.