282 H E 
Water expands about the 24th part of its bulk between 
freezing and boiling; and glafs, in the fame interval, 
expands longitudinally the i20odth part, and confe- 
quently its dilatation, in all the three dimenfions,- mud 
amount to the 40odth part of its whole volume. The 
expanfioi: of water that correfponds to any temperature 
x is therefore denoted by (~^~) i and that of glafs 
'100/ 
by-. Equating thefe two expreflions, we obtain 
- 40,000 
— — * and therefore #=6°. This remarkable coin- 
24 4 
cidence feems to difpel every fhadow of doubt, and we 
may embrace it as an eftablilhed fa£t, that the fucceffive 
dilatations of water, counting from zero, are as the na¬ 
tural progrefiion of numbers.” 
The moft important queftion relating to this fubjeft, 
which has agitated the minds of philofophers, is, Whe¬ 
ther heat be matter or motion. The ancients undoubtedly 
conceived that heat was material; and this opinion ap¬ 
pears to have been, generally received till about the 
time of lord-chancellor Bacon, who in his treatife Dc 
Forma. Calidi, confiders heat as the effect of an expanfive 
undulatory motion in the minute particles of the body, 
by which they tend with fome rapidity towards the cir¬ 
cumference, and -at the fame time incline a little up¬ 
wards ; Which idea was, with fome modification, adopted 
by Defcartes, Newton, Boyle, and other philofophers 
of that and the fucceeding age. The modern chemifts, 
however, from their being more ufed to the obfefvation 
of the eff'e&s of this agent, in the innumerable experi¬ 
ments of more enlightened days, revived the doftrine of, 
the materiality of heat; which doftrine again became ge¬ 
neral, and continued fo, till fome recent experiments of 
count Rumford, which tended to prove that heat is impon¬ 
derable, and capable of being produced ad infinitum from a 
finite quantity of matter, again involved the queftion in 
confiderable doubt. It is an undoubted fadt that when 
water freezes, a portion of heat is given out by it dur¬ 
ing the congelation, which is fo confiderable, that if we 
were to conceive it to be imbibed by an equal quantity 
of water at the temperature of 32° of Fahrenheit’s ther¬ 
mometer, the latter would be heated no let's than 140 0 , 
or to 172 0 . If, therefore, heat were a ponderable fub- 
ftance, it might be imagined that a given quantity of 
water would become lighter when frozen in a vefl'el her¬ 
metically fealed. Count Rumford accordingly made 
this experiment with great care by the help of a balance 
of extreme accuracy ; but the refult was, that the ice 
produced appeared to be of precifely the fame weight 
as the water, had originally been of at the temperature 
of 6i°, viz. 4214-28 grains; from which he infers, that 
all attempts to difcover any effedt of heat on the appa¬ 
rent weights of bodies will be truidefs. 
The other deduction, of the poftibility of producing 
an inexhauftible fupply of heat from a given quantity of 
matter, leems to have been fuggefted to count Rum- 
ford’s mind, - by the refleftion that fire is produced by 
rubbing two pieces of dry wood fmartly againft each 
other. With this faift in view, the count procured a folid 
cannon rough from the foundery; and caufiug its extre¬ 
mity to' be cut off, he formed, in that part, a folid cy¬ 
linder attached to the cannon 7! inches in diameter, and 
9-gj inches long. It remained joined to the reft of the 
metal by a final 1 cylindrical neck. In this cylinder a 
hole was bored 3-7 inches in diameter and 7-2 inches in 
length. Into this hole was put a blunt fteel borer, 
which by means of horfes was made to rub againft its 
bottom ; at the fame time a finall hole was made in the 
cylinder perpendicular to the bore, and ending in the 
folid part a little beyond the end of the bore. This 
was for introducing a thermometer to meafure the heat 
«>f the cylinder. The cylinder was wrapped round with 
A T. 
flannel to keep in the heat. The borer rubbed againft 
the bottom of the hole with a force' equal to about 
fo,000 lbs. avoirdupois, and the cylinder was turned 
round with the rapidity of 32 times in a minute. At 
the beginning off the experiment the temperature of the 
cylinder was 6o°; at the end of 30 minutes, when it had 
made 960 revolutions, its temperature was 130°. The 
quantity of metallic duft or fcales produced by this fric¬ 
tion amounted to 837 grains. Now, if we were to fup- 
pofe that all, the caloric was evolved from thefe fcales, 
as they amounted to juft ^5-part of the cylinder, they 
muft have given out 948° to raife the cylinder i°, and 
conf'equently 66360° to raife it 70° or to 136°, which is 
certainly incredible. 
Count Rumford contrived, with his ufual ingenuity, 
to inclofe the cylinder above defcribed in a wooden box 
filled with water, which effedtually excluded all air, as 
the cylinder itfelf and the borer were furrounded with 
water, artd at the'fame time did not impede the motion 
of the inftrument. The quantity of water amounted to 
18-77 lbs. avoirdupois, and at the beginning of the ex¬ 
periment wa$ at the temperature of 6o°. After the cy¬ 
linder had worked for an hour at the rate of 32 turns in 
a minute, the temperature of the water was '107 0 ; in 
jo minutes more it was 178°; and in 2 hours and 30 
minutes after the experiment began, the water a&ually 
boi/ed. According fo the computation of count Rumford, 
the caloric produced would have been luflicient to heat 
26-58 lbs. avoirdupois of ice-cold water boiling hot; 
and it would have required nine wax candles of a mode¬ 
rate fize, burning with a plear flame all the time the 
experiment lafted, to have produced as much heat. In 
this experiment all accefs of water into the hole in the 
cylinder where the friction took place was prevented. 
But in another experiment, the refult of which yvas 
precifely the fame, the water was allowed free accefs. 
“ By meditating on the refults of thefe experiments, 1 
(fays count Rumford,) we are naturally brought to that 
great queftion which has fo often been the fubjeiSt of 
Speculation among philofophers, namely, What is heat > 
—Is there any fuch thing as an igneousfiuid? —Is there 
any thing that can with propriety be called caloric? 
“ We have now feen that a very Confiderable quantity 
of heat may be excited in the friction of two metallic 
furfaces, and given off in a conftant ftream or flux in all 
direflions, without interruption or intermiflion, and with¬ 
out any figns of diminution or exhatiftion. From whence 
came the heat which was continually given oft’ in this 
manner in the foregoing experiments ? Was it furniflied 
by the fmall particles of metal detached front the larger 
folid maffes on their being rubbed together ? This, as 
we have already feen, could not poffibly have been the 
cafe.—Was it furnifhed by the air ? This could not have 
been the cafe; for in three of thefe experiments, the 
machinery being kept immerfed in water, the accefs of 
the air of the atihofphere was completely prevented.— 
Was it furniftied by the water ’which furrounded the 
machinery ? That this could not have been the cafe is 
evident; firft, becaufe this water was continually receiv¬ 
ing heat from the machinery, and could not at the lame 
time be giving to and receiving heat from the lame body ; 
and, fetondly, becaufe there was no chemical decom- 
pofition of any part of this water. Had any fuch decom- 
polition taken place (which indeed could not reafonably 
have been expedited), one of its corhpound elaftic fluids 
(moft probably inflammable air) muft at thejame time 
have been fet at liberty, and, in making its efcape into 
the atmofphere, would have been detected ; but though 
I frequently examined the water to fee if any air-bubbles 
rofe up through it, and had even made preparations for 
catching them in order to examine them if any ihoulcl 
appear, I could perceive none; nor was there any fign 
of decompofition of any kind whatever,, or other chemi¬ 
cal procels going on in the water. 
“ Is it poilible the heat could have been fupplied by 
means 
