The loss, or matter of loss which fire promotes to fluids, appears as air-beads on the sides and bottom within the vessel on the fire, before the water comes to ebullition: these beads cannot be made to rise in the water by any manner of agitation, which is proof they have not come from the fire, and through the rigid bottom, or ascent and escape are inevitable. When the bottom has been sufficiently de-electrised by the fire, they are pressed through it to the fire; or if the vessel be removed and placed on the ground, they become dispersed through the water insensibly. The like spherules collect on an egg while boiling, which cannot be anything issued from the fire to the surface of the water, then precipitated on the egg. On the bottom of a glass-retort suspended over a lamp, the like spherules collect, from which it is supposed that water never touches the bottom of any containing vessel; it must touch that which it wets. That air suffers loss to fire, is made evident by the air being deprived of, or losing its oxygen during combustion; and from both fire and flame becoming extinguished in a limited quantity of respirable air, in consequence of having lost its oxygen to the combustible, while in the state of fire. Solids, as polished metals and glass, when they experience no change of weight, lose to the fire imponderable elementary matter only. So is it when the hand is presented to the fire, it loses electric matter, and the loss it suffers promotes the sensation of heat: when the hand afterwards touches a body, supposed to be cold, it acquires elementary matter from that which is touched. In every instance the body, solid or fluid, supposed to be _heating_, is losing elementary matter; and that which is said to be _cooling_, is acquiring the like matter; the hand _loses_ to the former and _receives_ from the latter electric matter. THE MEDIUM OF FIRE.