A peculiar medium is formed within a fire, towards the composition of which the fuel contributes more or less of its elements; which is made manifest in a piece of wood or paper when held within the fire, being brought to the state of combustion, and without touching the fuel, (heat, be it remembered, is no more physical than shadow.) The like medium is formed from the elements contributed by flame, and whatever of elementary matter the atmosphere may contribute beside. High above the flame of a lamp combustion and fusion are effected the same as within, or in contact with the flame. Between the cupped hands this medium is receivable, and may be carried from the flame of a candle to the wick of a different candle just blown out, which it re-illumines. There being little or none of the medium of fire attendant on a detached ignited body, favours the conjecture that the fuel during combustion contributes somewhat of its elements towards the formation of the medium of fire. Hence, although not included in the nomenclature of chymistry or any other, the medium of fire should have place on the list of realities. As all bodies include more or less of free elementary matter, which excludes its equal in volume of the medium of space, so to admit medium of space in order to cause change in the constitution of a body, the body must undergo previous de-electrisation: the law is general. The medium of space being the expanding and decomposing cause, by means of its centrifugal pressure within bodies, to prevent its being in excess and effecting such changes spontaneously, productive of the decomposition of all things, all bodies are protected or retained in their present condition by the electric matter within them, which excludes the decomposing cause. Within the medium of fire all kinds of bodies become de-electrised; all suffer loss of electric matter, which is succeeded by influent medium of space, the centrifugal pressure of which affects the several changes to which bodies are liable previous to ultimate dissolution into the elementary state. In promoting the de-electrisation of every kind of body, and to the extreme, which no other individual medium or menstruum can effect, consists the universal utility of the medium of fire. EXPANSION. The theory of expansion is of easy comprehension; it consists in previous de-electrisation, succeeded by influent medium of space, which, by acting with centrifugal pressure, produces the phenomenon of expansion. The general pressure is the expanding cause, by reason of the portion of medium of space within all bodies being continuous with the medium of pressure in general space.