6 THEORY oF 
This fluid may pofflibly be the fame with that which 
being attracted by and entering into other more folid mat- 
ter, dilates the fubftance, by feparating the conftituent par- 
ticles and fo rendering fome folids fluid, and maintaining 
the fluidity of others; of which fluid when our bodies 
are totally deprived, they are faid to be frozen; when they 
have a proper quantity, they are in health, and fit to per- 
form all their funétions; it is then called natural heat ; 
when too much, it is called fever; and when forced into 
the body in too great a quantity from without, it gives 
pain by feparating and deftroying the flefh, and is then 
called burning; and the fluid fo entering and ating is 
called fire. 
While organized bodies, animal or vegetable, are aug- 
menting in growth, or are fupplying their continual wafte, 
is not this done by attrating and confolidating this fluid, 
called fire, fo as to form of it a part of their fubftance ; 
and is it not a feparation of the parts of fuch fubftance, 
which diflolving its folid ftate, fets that fubtil fluid at lib- 
erty, when it again makes its appearance as fire? 
For the power of man relative to matter, feems limited 
to the feparating or mixing the various kinds of it, or 
changing its form and appearance by different compofiti- 
onsof it; but does not extend to the making or creating 
of new matter, or annihilating the old: thusif fire be an 
original element or kind of matter, its quantity 1s fixed and 
permanent in the univerfe. We cannot deftroy any part 
of it, or make addition to it. We can only feparate it 
from that which confines it, and fo fet it at liberty, as when 
we put wood in a fituation to be burnt; or transfer it from 
one folid to another, as when we make lime by burning 
ftone, a part of the fire diflodged from the fuel being left 
in the ftone. May not this fluid when at liberty be capa- 
ble of penetrating and entering into all bodies, organized 
pr not: quitting eafily in totality thofe not organized, and 
quitting 
