F I R 
matter •, but this is contrary to experience ; at leaft, the 
fire contained there is no hotter than the mercury itfelf; 
for if a drop or two of water be in a frofty feafon 
fprinkled both upon the upper part of the tube, fup- 
pofed to be full of fire, and on the lower that is full of 
mercury, they will in each place freeze alike ; fo that 
there is no more pure fire in a perfect vacuum, than 
in any other place. 
But whereas it has been faid, that fire is found in all 
bodies, to prove this, fet gold againft the vacuum be- 
fore-mentioned, and this gold, though the moft pon- 
derous of all bodies, will not contain more fire than 
Huygens’s vacuum, as appears from the thermo- 
meter. 
But the fire in gold, when ready to fufe, is pure 
fire ; for a mafs of this being once heated red hot, 
will retain this fire perfedtly for three days ; nay, the 
prince of Mirandola and others, have kept gold ig- 
nited for two months, without any diminution of 
weight. 
Mr. Gravefande, Phyf. Element, fays. That bodies 
of any kind, being violently moved againft one ano- 
ther, will grow hot by fuch fridtion ; and this to a 
confiderable degree, which fhews that all bodies have 
fire in them ; for fire may be put in motion, and fe- 
parated from a body by fuch rubbing, but can never 
be generated that way. 
Mr. Boyle, Mech. Prod, of Heat, fays. That although 
quickfilver is allowed to be the coldeft of all fluids, 
infomuch that many deny, that it will produce any 
heat by its immediate adtion on any other body, and 
particularly on gold ; yet feveral trials have allured 
him, that a particular mercury may by preparation be 
enabled fuddenly to infinuate itfelf into the body of 
gold, whether calcined or crude, and become mani- 
feftly hot with it in lefs than two or three minutes. 
Mr. Gravefande fays. That quickfilver contains fire, 
is evident hence, that if you lhake it about in an 
exhaufted glafs, it will appear all luminous. 
Elementary fire of itfelf always lies concealed ; nay, 
it may be perfedly undifcoverable, where it is in the 
greateft quantity * as is evident in the torrid zone, 
where the fnow never melts, notwithftanding the great 
abundance of fire. 
This fire, in itfelf thus perfedly latent, may difco- 
ver itfelf to be prefent by five effeds ; i ft, by rare- 
fying bodies, and particularly air •, zdly, by light •, 
3dly, by colour ; 4thly, by heat •, and 5thly, by 
burning. 
That there is a good quantity of fire even in the 
coldeft places, and in the coldeft bodies, is confirmed 
by the following experiment : if you take two large 
iron plates, and rub them brifkly together in Iceland, 
which is only twelve degrees fhort of the north pole, 
in the moft frofty feafon, and at midnight, they will 
grow warm, glow, ftfine, and heat to fuch a pitch as 
not only to rarefy the fpirit in the thermometer, but 
even to ignite, and at laft to fufe. 
. Now the fire here found is either created de novo, or 
it was there before, but nobody will affert its crea- 
tion ; and accordingly, unlefs it be furnifhed with a 
proper fuel, it will be foon diffipated again, but not 
annihilated ; and of confequence it pre-exifted, and it 
appears to be true fire by its rarefying the fpirit in 
the thermometer. 
From this, and many other experiments, it is evi- 
dent, that fire is always found in all parts of fpace, 
and in all bodies equally fpread on the utmoft top of 
the higheft mountain, as in the fubjedt valley, or in 
the deepeft cavern under ground, and in every cli- 
mate,, and at every feafon. 
The equable diftribu-tion of fire in all places being 
proved, it fhould thence follow, that there is the fame 
degree thereof every where ; which would really be 
fo, were it not that fire happens by one means or other 
to be more collected in one place than another. 
But, notwithftanding the equable difference, &c. of 
fire through all the mundane fpace does not hinder, 
but that, to our fenfes, it appears very unequal in dif- 
ferent places * and hence we have two vulgarly re- 
puted fources or funds of fire, viz. in the fun, and 
the center of the earth. 
As for the firft, we have the concurrent opinions of 
the philofophers of all ages, but one excepted, who 
held the fun to be cold. 
As to the fecond, the central fire, it is manifeft that 
there is an ample proportion of fire under ground ; 
and even, that fire appears much more abundant 
there than on the furface ; fo that at leaft, a fubter- 
raneous fire muft be granted. 
Thus they who dig mines, wells, &c. conftantly ob- 
ferve, that while they are but a little below the fur- 
face, they find it a little cool ; and as they proceed 
lower, it proves much colder, as being beyond the 
reach of the fun’s heat, infomuch that water will 
freeze almoft inftantaneoufiy, and hence is the ufe of 
houfes. 
But a little lower, about forty or fifty feet deep, it 
begins to grow warmer, fo that no ice can bear it ; 
and then the deeper they go, ftill the greater heat •, 
till at length it endangers the ftoppage of refpiration, 
and puts out their candles. If they venture yet farther 
with a lighted candle, the place ihall be immediately 
found full of flame, as once happened in the coal-pits 
in Scotland, where a hardy digger, descending to an 
unufual depth, with a light in his hand, the fumes, 
which were there found very copious, caught fire 
thereby, and burnt the whole mountain down. 
Therefore it feems as if nature had lodged another 
fun in the center of the earth, to contribute on its 
part to the giving motion to bodies, and for the pro- 
moting of generation, nutrition, vegetation, germi- 
nation, &c. of animals, vegetables, and fo fills. 
As to the origin of this fubterraneous fun, fome 
doubt whether it were formed there in the beginning, 
like the fun in the firmament, or gradually produced 
by a fecondary colledtion of vague fire into this place. 
What makes in favour of the former opinion, are 
volcanos or burning mountains, which feem to have 
exifted from the firft ages ; for the flames of mount 
iEtna are mentioned as of great antiquity, and there 
are likewife fuch mountains found in the coldeft re- 
gions, viz. Nova Zembla and Iceland, as well as the 
hottell, as Borneo, &c. 
It cannot be reafonably pretended, fays Mr. Boyle, 
that the fubterraneous heat proceeds from the rays of 
the fun, fince they heat not the earth above fix or fe- 
ven feet deep, even in the fouthern countries ; and if 
the lower part of the earth were of its own nature 
cold, and received the heat it affords only from the 
fun and ftars, the deeper men defcend therein, the lefs 
degree of heat and fleams they would meet with. 
The fun contributes much in bringing fire to light, 
by reafon of his rapid motion round his axis ; whereby 
the fiery particles, every where diffufed, are directed 
and determined in parallel lines toward certain places 
where its effedts become apparent. 
And from thence it is, that the fire is perceived by 
us when the fun is above ; but that when he difap- 
pears, his impuife or prefiion being then taken away, 
the fire continues difperfed at large through the ethe- 
real fpace. 
There is not, in effedt, lefs fire in our hemifphere in 
the night time, than there is in the day time ; only it 
wants the proper determination to caufe it to be per- 
ceived. 
The effedts of elemental fire may be increafed divers 
ways, viz. firft, by attrition, or a fwift rubbing or 
agitating one body againft another. This is very ma- 
nifeft in folids. The attrition of a flint againft a fteel 
produces fparks of fire •, and likewife in fluids, the 
violent agitation of cream, by churning, will produce 
a fenfible warmth, and feparate it into butter ; and 
this effedt is rendered ftill more difcernible by a ther- 
mometer. 
And the heat of animal bodies is owing to the agita- 
tion and attrition of the parts of thefe juices againft 
each other, and the ftdes of the veffels. 
The fecond manner of increafing the effedt of ele- 
mentary fire is, by throwing a quantity of moift or 
green 
