‘HEA FT. 
whilft the air, from which the metal derived all its heat, was whereas it is feen, that the eirculation ma be amazingly 
only unpleafant. * From thefe experiments, it if concluded quickened, whilft there is little increafe of “6 animal heat. . 
nclude in general, from t e experiments and 
e of the air in fummer and 
» confequently, changes 
Loge es See 4q 
ving a name to a own caufe 1s power, how- his fituation on the furface of the globe with much lefs 
ever it aéts, feems to attend life very univerfally ; Mr.Hun- inconvenience or injury than he could otherwife have. done. 
ter found a ‘carp preferve a coat of flui water round him fame power likewife ha 
and with their clothes on ; nor was the heat of Dr. Blag- tached from the air, the arterial blood, when it returns by. 
den’s body: at all invreafed, though the velocity of his pulfe’ the pulmonary -vein, will have its fenfible heat greatly. di- 
A blaft of , 
heated air from'a pair of bellows was feareely to be endured veffels which are in contaét with it, and from the parts ad- 
for the following obvious reafon : when the fame air re- jacent. And thus the fame procefs, which in one cafe fup- 
mained for any time in contaé& with the body, part of its plies the animal with heat, according, to Dr. Cra s 
heat was deltroyed, and, confequently, the body was fur- th ry, will now become the inftrument of producing cold ;, 
rounded with a colder: medi e air of theroom; and the quantity of cold produced will be in pro 
: portion to. 
whereas, when frefh portions of the air were applied to the the velocity of the blood throu gh the lungs, and the fulneis 
ody i i and frequency of the refpiration. Thus, in winter feafons,, 
main in contact a fufficient time' to be cooled, the heat and cold climates, the veffels on the furface of the body are 
t ua 
leafed, and brought again into the cold air, fhe appeared not nithed: betides, if. thee quantity of heat abforbed: by the 
to have received the leaft injury. - In the fame heated air,. vapour exhaled in. refpirati 
which they breathed, e gs were roaited quite hard in 20/, maining portion of the heat depofited by the air is not fuf- 
d din 33'; and by blowing theair ficient to fupport the temperature of the arterial bleod, fome 
upon fome of them,’ in 13/, — degree of cold will be produced in confequence of the change 
The effect of evaporation, in preventing certain bedies, which the blood undergoes in the lungs.. Martine’s. Eflayy 
and particularly fluids, from rectiving a degree of heatequal Eff. vi. Phil. Trang: vol. Ixy, part i. art. 12. Id.ibid- 
to that of the air, is thewn by fome of thele experiments to vo iil. pa 
be very confiderable. In the great ‘heat jut mentioned, art.2. Crawford on Heat, &c. P- 31. 80, & 
Pure water, expofed in an earthen veffel during an -hour and. Heat, in Geography. The diverfity of the heat of chmes 
a half, acquired only a heat of 140°, aid ate ifferen the: 
tinued ftationary above an hour, at a degree much! below the fun’ aes 
Boiling point ; but when its power of evaporating was It is. fhewn in mechanics, that a movin body friking 
checked, by dropping a {mall quantity of oil on its furface, perpendi ah as 
it boiled very brifkly. A faturated olution of fea-falt ac. and that a body ftrikin obliquely, aéts with the lefs forces’ 
quired a heat of 230°, and was, confequently,; brought into the more it deviates from the perpendicular. Now te 
za brik eb llition, on covering its furface. with a layer of. moving in right lines, muft obferve- the fame mechanical Jaw 
ae as other bodies; and confequently its aétion mutt be mea~ 
count of fimilar ex-. fured by the fine of the angle of incidence : 
. 
erwards con- and feafons arifes from the different angles under. which 
Wes hg . 
g-room of the ho ~ ftriking on any obftacle in a direétion para e thereto, has 2 
fenfible effet, beca ratio is ak D 
ees any aa 
that it is produced ‘by. the'attrition of the globules of the ateording to the eee of the angle of incidence, or to the 
— fluids againit the fides of the containing’ veffels’; perpendiculars let fall’ on~ the plane ; whence, the vert 
ui ° s i bb : So eye . ‘ 
