It does not appear, however, that all bodies have an equal attraction for the matter of fire. If a rod of iron is put into the fire for a short time, the end which is at a moderate distance from the fire will almost burn the hand; but a rod of wood, of the same length will be consumed to ashes at the end which is in the fire, before the other end is sufficiently heated to burn the hand. A ball of lead, and a ball of wool, may be of exactly the same temperature by the thermometer, but they will not appear of the same degree of heat on applying the hand. If they are of a temperature below that of our bodies, the lead will appear much colder than the wool, because it attracts the heat more rapidly from the hand; if they are of a higher temperature, the lead will appear much hotter, from the facility with which it parts with its heat. This property in bodies is called their _conducting_ power; and those bodies through which the element of fire most rapidly circulates, are called good conductors. The power of conducting the matter of fire seems to depend upon the texture of bodies, that is, upon the contact of their parts; hence the excessive slowness with which heat is communicated to bodies of a rare and spongy texture. Thus flannel, wool, and feathers, are considered as warm coverings, not because they possess more heat in themselves--for they serve to preserve any cold body in a cool state better than other substances--but because they prevent the escape of the animal heat from our bodies. The matter of fire will exist in a state of combination, in a _latent_ state, so as not to be perceptible to our senses. It will be found by observation, that every body which exists contains a quantity of the matter of fire in a fixed or neutralized state, disarmed of all its active, penetrating, and destructive qualities, like an acid and an alkali in combination.