: 
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Jg-7, which is made of tin, and painted with oil colour, to 
prevent ruft. When this machine is employed, the middle 
owed to drain 
a aay and the fubftance fubmitted to experiment being 
placed in the interior cavity, it is inftantly clofed. r 
filengaged during the cooling of the included body, as the 
heat difengaged is evidently {pent in converting part of the 
Interior ice into water, atthe rate of 135° or 140° for eac 
pound of water. i 
@ pound of ice 
fubftances to be operated upon are in 
cket, fig. 8, the cover of which has an Cm fitted with 
a cork, into which a fmall thermometer is fixed, or fome- 
times ama . 10, with a fimilar thermometer, which 
flands in the interior cavity upon the fmall cylindrical fup- 
port RS, fg. are mu taken that no communi- 
cation fubfift between the middle and external cavities of the 
calorimeter ; left the ice melted ir fhoul 
erformed. en the in‘trument is to be ap- 
P d the heat given off by animals, and by com- 
ultion, &c. two f ubes are neceflary to be connected 
with the inftrument, the one to convey frefh air into the 
imterior, and the other to take off the ufed air. Wh 
the i for heat are 
periment is p 
lied to fin 
Pacity of the cal 
the nag Seriya of 32°; then the weight of the melted ice 
dene. und = qw, and the weight of the body being — 
ated by 5, and the number of degrees of temperature it 
Js reduced by a, we have this formula ; “ee = the capa- 
S, 
Lavoifier and La Place found 7.7Ibs. of iron heated to. 
207-5, melted 1,11lbs. of ice; here w = 1.11, ¢ = 77s 
and m = 2077.5" — 327 = 1467. whence ensured sata 
7.5 3 Fraas 175+5 x 77. 
the obitruétion of its defcent by an agglutination of the 
fragments of ice in the lower part of the veffel. See 
Communication 4 Heat, including its radiation, refradion, 
hy ; 
e communication of heat from one body 
ters. Many important facts have recently 
been afcertained on this fubje€&t by count Rumford, Dr. 
> 
and that the refleéted heat is conveyed omen a the air by 
i es not feem 
their heat in every direétion, when furrounded by an elattic 
medium or a vacuum ; the other, the. flow and gradual com- 
munication of heat, fuch as is experienced along a bar of 
iron when one end of it is put into a fire; the heat appears 
to travel from one molecule to another till it arrives at the 
extremity, and is then thrown off or radiated into the air. 
“he laws of the radiation of heat and the fubfequer 
refleGtion of it, have lately been inveftigated with great {kill 
by Mr. Leflie, and fome new and unexpected 
been obtained. e his * i 
paper, &c. it will radiate eight times as much 
i If the bulb of a 
infoil, the impreflion 
black paint, r, glafs, &c. are difpofed to: 
jefleee it but when elevated in temperature 
