DENSITY. 
double force: it gel be split into half the pangs sf 
a treble force, y bec a into a third part o 
a n art has not been a 
It has alfo been obferved, that by removing the p 
quantity of air will be enabled to expand itfelf; nor has any 
limit been difcovered to this expanfion. Other bodies are 
compreffed, and become more denfe in confequence of the 
application of an adequate force; but they do not follow the 
fame regularity as air; nor do they recover their entire ori- 
ginal bulk when the preffure is fais All metallic bo- 
dics, by prcfling, laminating, or hammering, may be perma- 
nently reduced into a {malier ae or rendered more denfe; 
but itis «:t in our power to fay how far their denfity may be 
incre 
tive asia nie ie not be i » pert fe& contaé& with 
other; but that they aaah contain a great oa pores 
or vacuities ndeed, fir Ifaac Newton wa oe inion, that 
goid which is ‘the deulett bady pext to nee 18 
likely to contain more pores or vacuities a real folid mat- 
ter. It is, ome to be obferved, that this opinion is 
more verbal, than reai; for whe 1 in common lanzuage we 
talk of pure gold, or pure filver, or pure water, &c. we 
mean that the gold or the filver 1s unmixed with other me- 
tals. or that the water contains no folid extraneous matter j 
r prefling; as under that operation the :retallic fubftance 
is unavoidably heated. exift e ele€tric fluid 
in confiderable quantity is rendered more than probable 
ly I 
preffible, give 
e comprefiion of air produces heat fiscar to "fet 
fire to ‘ight combuilible bodie 
The denfities a7 ei are alfo sa teed i by cooling, or by 
‘the abftraction of heat. This law, however, is not general; 
and denfer by cooling, as far as about the goth degree of 
Fahrenheit’s thermometer; but below that degree the bulk 
of water is expanded by farther cooling; which is evidently 
owing to a rt cong ae viz. to the fade of water dif- 
pofing themfelves in a uliar order. The fame thing, 
under cia limitations, has been obferved in various other 
odies. 
able philofophers, as bein 
ng 
a fubject intimately connected with, and fubferviert to, | 
various inportant branches of natural paren» and to the 
s. The dentities of folids and fluids are, in fad, the ir 
fpecific gravities, the 
knows to be extenfively ufeful. iT 
The mutual prcffure of fluids upon each other, allo, of 
folids upon fluids, and vice verfa, Hoe are of the utmoft 
importance in hydraulics, in naval architeQure, &c. 1s en= 
tircly dependent upon their peculiar alee See Hy- 
prautics snd Navaut Arcuirecture. In chemical ope- 
rations, the devfitics of Buide, and Peet of faline folu- 
tions, are carefully attended to: for the cryftaliization, and 
the feparation of falts, ay depend ae the proper 
degree of denfity to yal the brine is ee See 
CHEMISTRY, Sats, and CRYSTALLIZATIO 
The inve tigation oF he various ‘denies of the atmof- 
phere at diff-rent times, and at different heights above the 
furface of the earth, ena ebike us, befides other ufes, to mea- 
fure altitudes by the barometer. 
With refpe& to the various ceafity of the atmofphere it 
will be necellary to give a general idea in this place, the- 
more intricate a of it being treated of under the articles 
PHERE, ATMOSPHERICAL LoGarirHMic, and 
Banomeren. 
Air a€tually taken in bottles, at different heights above 
the furface of the earth, (as far as human beings could af- 
cend,) one oo examined w ith all due precautions, has 
been found to be a 
greater height. h 
been performed on the compreffibility and clafict ty of io 
w 
t 
phere ; that it is lefs denfe according as the place is more 
diftant from the furface, becaufe the fuperincumbent air is . 
lefs high; and laftly, that it is impoffible for us to fay how 
far the atmofphere is extended, becaufe we are not ac- 
quainted with the utmoft limits of the air’s expanfibility: 
Befides the compreffion arifing from the weight of the 
fuperincumbent air, which undoubtedly is the principal caufe 
of the various denfity of the atmofphere ; other caufes con- 
In fhort all the con- - 
e admixture of vapours and other fluids; and, 5. The 
stration of the fun and the moon. 
he abovementioned faG&s, the denfizies, and of 
San. the preffures of the a atmofphere, for different alti- - 
tudes above the furface of the earths are calculated on the 
ne the barometer, b 
or preffures at different altitudes, will of courfe, indicate 
the correfponding seat AROMETER, and the. 
other articles above re 
DE 
NSITY of he Sin a Planets. To determine rs 
denbty. 
