New Experiments upon Heat. By Colonel Sir Benjamin Thompson, Knt. F. R. S. In a Letter to Sir Joseph Banks, Bart. P. R. S. Author(s): Benjamin Thompson Source: Philosophical Transactions of the Royal Society of London, Vol. 76 (1786), pp. 273-304 Published by: The Royal Society Stable URL: http://www.jstor.org/stable/106626 . Accessed: 17/05/2014 20:29 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. . The Royal Society is collaborating with JSTOR to digitize, preserve and extend access to Philosophical Transactions of the Royal Society of London. http://www.jstor.org This content downloaded from 91.229.248.141 on Sat, 17 May 2014 20:29:50 PM All use subject to JSTOR Terms and Conditions
Transcript
New Experiments upon Heat. By Colonel Sir Benjamin Thompson, Knt. F. R. S. In a Letter toSir Joseph Banks, Bart. P. R. S.Author(s): Benjamin ThompsonSource: Philosophical Transactions of the Royal Society of London, Vol. 76 (1786), pp. 273-304Published by: The Royal SocietyStable URL: http://www.jstor.org/stable/106626 .
Accessed: 17/05/2014 20:29
Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp
.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].
.
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XIVR New Experiments upon Heat. By ColonelSir Benjamn ThompSon7 Knt. F. R. S. In a -Letzer o Sir Jofeph: Banks, >Bsrt. P Re S.
Read Mar 9, I 7860
D E AR S TA,
HAVE at length be-gun the courfe of eexperimen-ts liparl heat whiclo 1 have fo loIlg had irl contemplation, azed I hav@
already made a diScovery, wilichX if lwot llesv to you, is perfed:ly fo to sme, >azd which;I think may leadto a furtherSkllowledge reEPeAi1lg the nature Of 11eat.
VOL. LXX. C)-o iExarnining;
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2 74 Sir BEND:M I N THOMPSON S: Examinitlg<the conduEtitlg power of air, at}d owf variou6
other fluid and Iblid bodies, withregard to heat, I wasu led to E . . ..
examille Vthe- collduAiizg power of the: firttcelD2n vacGume
Fr-oln tlae Rriking analogy betweell the eleEtric fl uid ard heat refpeditlg their conduEtors and Ilon-conduAors (havitzg found that bodies, itl general *hich are XcotlduEtors of the eleAric fluid, ae likewiCe good cotldudors of heat, and, on t-he coll- trary, ttlat eledric bodies, or fuch as are bad conduEtors of the cleAric fluidS are likewife bad conduEcors of lleat) I was led to imagine that tlae Torricellian tacuutn, which isknowll to
\ . .
affnvd fo ready a paiage to the eledcric fluid,3 would allb have aSorded a ready paIiage to heate
The common experiments of heating and cooling bodies ulader the receiver of an air-pump I corlcluded irladequate to deterrninillg this queRion; rzot only on account of the impof- fibility of making a perfeA void of air by mealls of the pump, but alfo on account of the moiI} vapour, which exhalitlg from the wet leather and the oil uSed in the machineS expallds under the receiverX and fills it with a watery fluid, which, though extremely rare, is yet capable of cotlduEting a-greatgdeal of heat: I had recourfe therefore to otheir coIltrivallces
I tooli a thermometer, utlfilled9 the diameter of wrlloSe bulb (which ras glol)ular) waswjuI} half an in-ch, Paris xneafure anci fixed it in the cetater of a hollow glafs ball of the dxam^eter of Ix Paris inchS ln fuch a mantler, that the Short l-weck or openlng of the ba11 being foldered faR to tlle- tube of tlle tElermcmeter yt lines above its bulb, the lJulb of the ehermomerer renlained fixed ill the center of tlle ball, alld conSequelltly was cut off from all cointnunication with the - external air. In t-h-e bottoml of tlle glaNs ball was Exed a finall h<)Ilovv tube or po;lt which projeding outwards was foldered
to
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ExperifrerGs span Mft 275 to the end of a common l)aroLncter tulJe atbort 32 inches in length} XaIld by means of this opening the Epace betwee-l the
ternaI i:urface of the glafs ball and the bulb of the tllermo- .... . . . , .. \
meter was filled with llot mercv?ry, wllicll had beetl prev-ioufly freed of air and moiRure l)y boiling. The ballX and alioE the barometrical tube attached to its beiLlg filled with l*ercury, tlle tube vvas calSefully iverted, atld its operl elld placed ill a bowl itl which there svas a quarlt:ity of mercury. The itlfirumellt now lDecame a lJarometer9 atld the mercury defcendi1zg from the ball (Xvhicll was now uppermoR) left - the fpace fur- rounding the l)ulb of the thertnotneter free of air. The mer- cury having totally quitted the glaSs lDall, and having funli itl the tube to the height of 28 itlches (being the height of the mercury ill the commorl barotneter at that titne), svith a lamp and a blow-pipe I meIted tlle tube together, or feaIed it l-ler- meticallyS about three-quarters of an illch bWlosr the ballS and CUttillg it at this plate with a fiIae file, I fcparatetl tIle eball from the long barometrical tube4 'lehe thermotutter being -afterwards filled with mercury itl the common wayX I now polEeff8ed a thermometer whoSe bulh was confined itl tlat eetter Sof a IJorricellxan vacuum arld urhich ferved at\ tlle falme time as
the body to be heated, and as the irlfirumetlt ior meaftlrirg the Iheat comulunicatedX
Experimenx N°- t.
X With this infiluluent (fee fig. I .Tab.VI.) E made the followlng experiment. Having plunged it into a veXel filled with water, warm to the 1 8th degree of R }Easbsux9s Scale and fufEred it to
remain there till it had acquired the temperature of the waterX that ;$ . . . .
002 to
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r fay, till the mercury in the incIoSd thertnometer Roodsat t8° I took it 0a3t of tbis teflel -atlds pl\Xtaged it fuddellly into a tflel of lsoiling water, and holding it in thewwater (which tras kept cotlAuntly boiling) byw the end of ttle tubet in fuch a manner tllat the glaSs ball} in the cQter of which wasAthe
bulb of the thernzonerer, was juf} fubmergHfi Is obSerared:* tht
nurnber of degrees to whicll tbe mercury in- the thermouleter
hal:arilin at dEerentpeliodsvo£ time counted fibm thE moZ
ment of its immerIlon. Tllus, afier lt had rematlied in the
boilitIg water X min. 30 {ic. I fbutuds the mercurg Wad riin;
firom 18° tO Z7t Afier 4 nlitlutes had elapfed,, it had rllEn t
44°<T 3+ and At e CI1d Of S S1UUTeSit hAd SiX11 TQ 48°T%T.
Eerxmvnx w 2+ ..
TAkingitllowtof the boiltngwaterfIiSredittccoIt
gradually itl the air, and after it hXad acquired the temperatuw
of the atmobhere, whlch was thatof X 5Q R. (the weaths
lbeitag periEtly fitle), I broke off a llttle piece im the polllt of the MaIl tulze wlisSrmained atYthes bottn of the glafi ball, where it had been hermetsally;iZaled, sat-d of werfi the atmoI9heric air ruffied immediately into the ball The ball Iiirrounding the bulb of tlle thermometer being now filled with
air (inRead of ltiilg emptwda of air as it- was in the befom
mentioned experimealt I iated the end of the Iinall tube at
the bottom^d the gXafs leall hermeticallyy and by thatsmeans cut off all communication between the aior confined in the ball }nd sthe externaI air; anclewitvh the XinRrument B prepared I repeated the experiment befbre-mentoned, that is to fsty, I put
e into water warxned t t8°> alld when it-had acquired the tem-
peratum
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p;era:ture-of the watery I plunged it irito Iloillllg v7ater and obServed the times of the aCcent of tlle mercury- i<-n the thermo meter. They were as follosvs-..
Time Heat; eIapfedw acei}Sred.
Eleatatthe moment of beongplunged lnto} 18°1P<,., the bolling waters . * ,
R:om the refblt of theSe experTrnents it appears evidelltly, t:liat the*Torri£t11ian vacuumy which aSords fo ready a.palqage to the eleAric fluid, fo far from being a gxd coiadudor of heat?
:;
is a much woirSe one :than commotl airS whicll of itftif is recliolled atnotlg the wo-rR :- -fSr in the la{} experimentS whetl the bulb of the thermometer was furrounded with air, and the inRrument-N^rxas Wullged into- boiling; Watele the mercury roSe frc)m 18 to 27° iSu 45 Seccjnds, but irl the fol*ner expesSSxellt9 whel1 it sras furrotlnd-ed by aeTorricellian vacuumS it rewired r:o rerrwain ils the lJoilil1g<--waterF I xBiZute 3Q tCOlldS = 90 feCOlld$
to acquire that degree of Ileat. I11 the vactum it 1equired 5 minutes to riIc to 48o<2v; but in air it roId to that height in 2 minutes 40 feconds, and the proportioll of the ttnes in the otl1er obServations is n¢arly-the fame -as will appear by; th; follosvulgJableO
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The bulb of the thermortreter placed in> itlylo cerlter of the glafs ball, and
t_" t 4 _
Torricellian vacuum. gfurrounded by atr
(Exp. N° 1.) (Exp. N° 2.) lime Heat Time - Heat
Elapfed. acquired:. eIapfed. - acquired Uponbeingplunged into} E go I 8°
lsoila>g water Kg ; .S Ar*;s s O
. . . .
tffter remalV1tlg 11: lt I 30 Z7 ° 45 27 _ - I - O 3 Q1 w
4 0 44a9-<5 2 I ° 44o-Q
5 48 C 2¢ 40 48 I o
- 4 ° 56zv - _ 5 0 6O>9
-tRheSe expezritne-nts were- made at- Matlheimg upoll the iirR day of 3uly laR, in the prefetlce of vP*toRffor Hz:MMER, of the Eledcoral-Acade;my of Sciences of Manheim>-and -CHARL-ES ART ARIA, j Meteorological IrwR-rumenttmakeSr to the Academyw by whom I was- allJX:Lled.
Fil<ditlg the corsIlruEtion -of the inRrument made uSe -of ill thefe experiments:- attended with -much trouble-alld riIjue, on account of the difficulty of folderirlg the gl-afis- ball- to the tube of the therlnometer without at the fame tiale: either clofolzg up or otherwifeiinjurings the bore of thel tube, I had recou-^rfe to another contrivance much more colnmodious, atld- much cafier ill the-executiotls
At the etld of a glafs tu-be or cylinder ten or eIeven inches in length, and near three-quarters of an illch in diameter inter- nally9 I cauSed a hollow globe to be blowxl xi inch in dia
meteb
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meter, wii a-tu- opetlillg in tlle bottoln of it correfi?otlding: . i
with the bore of the tube, and equal to it in diameterX leaving
to the opening a lleck or {hort tube, about sn ith of three
quarters of all itlch in length. Having a thermolneter pre-
pated, w}aofe bulb was juR half an itlch ill diameterX alld
wlsofe freeziilg point fell at about 23 irlches alJove its bulb, I
gradua-ted its tu-be aoccordinzg to REA7:MURX?S ScaleX begi-lltling ats o°, and marking that point7 alld alfio every tenth degree above iti to 80° with: thzreads of fine filk bound rourld itX wllicll; being moiRened with lac varnilh adhered firmlyf to thegtulJeO Thtis-thermometer lfintroduced in-to the glaX cylinder and globe- juI} defcribedX l)y theeopetlitlg in th-e bottom of the globe, having firA choaked ttle cylinder at about 2 inches from its jurldrion with the globe by lleatingit, at-ld cro+vdring its fides illwards towards its axis, leaving only atl opening fufficient to ad1nit the tubeitf theethermome-ter. ?, The thermolneter beilg introduced into the cylitldefr in fuch a matlner tlaat the center
of its bullD coincided with the center o-f the globe- I marked a
place in the cylinder about tllree-quarters of an ixlch above
the 80th degree or-botling poitit upon the tube of the incloWed
thermometer, and taking out the thermorneter5 I clloaked the
cylinder again in this place. Introductng 1Row the thertuorneter
br the laPc timen tI clofEd- the openirl->g at the bortom oiS the
t;lobe at the lamp, tatking: careg befiore ]; brougllt it to the fire
to tultn the cyliNder upf<de downv and to let the bulbt of the
thermometer fall iIltO thc cylinder till it reRed upotl the lower
ehoak in the cy:linder By this lnean$ tlae loull) of the thermo
meter was renooved more thalw 3 inches from the flame of the;
lamp, Tlle opening at the botto-m -of the globe lteing 1lour . ,
cloSed atld the bulb ofE t-he thermometer beitlg fuffiered to
teturn into the giobe3 the end Qf the cJ7lilldex vas cut off to 4 -nvithin
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-Nvitllin about Atlaulf all inch of the upper clleak. rllis beitolg deff^e,, i:t iS p9Aill that the tube of the thermfometer 0 proJeAed beywd the td;of- ;he cylilder. Taking hold of the erdSof the ;tub¢, I placed tile lzulb -of -tlze thermometer- as nearly as potIEllJle in tXhe celater of the globe, utld .olServitzg and marking a vl?ointo ill tlle tube ilntnediately alos7e tlae upper choak of tlle cyiinder, 1
turtled the cyliIlder upfide dowas aald I;lfferillg the bulb of the thermometer to etlter the ;cylillder, atld reIt upoll tlle firll or losver choak (by XYhiChf mcalls the elld.of the tube of the ther- memeter ccime fulther out of the Acylinder)Xd the d Qf the tube was cut off at th.e Inarli jull natntio-tled (htlving firl} taketl care to melt the itltertlal cavityi vr lsore of the tube togetller a-t that place), aild a ftnall folid ball of bglaSs a little larger thatl the interllal dialneter or<.opuling of the clloA was foldered to the elad.of -the tilb¢¢ forming a little button or .iL1Q5, wh1ctil
xding upotlvthe upper choak of tlae cylitider, ferved- to fuf- pend the thcrtnometer ill fuch a malltwer that the center of its bulb coilicided with tlze Jcetiter of t1le globe in whichfit was tfhut tlpo The end Qf the cylinder al)sve the tw1pperkchoak }vcing nosr heated and dlawn out to a pOisl-t, or rat:hersabeing forlned into the figure of the -fruRutn of a hollow cone the end of it was foldered to the end of a barometrical tube, l3y the help of which tlle cavity of the cylinder atld globe - containing the therrnoxreter was comi)letely volded of air with*.mercury 5
when, the end of :hetcylinder beirlg hermetically fealed, the baroxnetrical rllbe was detached from it with a file, alad the thermometer was left completely ihut up iIl a Torricellian va- cuum, the center of tlle bulb of the thertnometer being conZ fined in the cellter of the glafs glabe, without touching it in asly part, by means of the two choaks ilu the cylilldero tand the buttoll upon the elld of the tube.
O.
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Of thefe i1]Rruluetlts I provided mySelf Witil tWrt>> A$ Sle&fly as poffilble of tlle fame dimetlf1otis, the otlen svIlich I Ilzall call N° I. being voided of air, ill the nlanller above deScribed; the other, N° z. being filled with air7 and herrnetically fealed.
With theSe two irlfErume1lts (fee fig. 2.) I made the fiollossr iIlg experiments UpOll tlle I Ith of July lafi, at ManheimX be- ntweetl the hours of teIl and twelveX the weather beilzg very fille atld clear, the mercury ill the barometelo Rad-ig at z7 i11Che$ I I linesS REATZMUR'S thertnotmeter at IS°, aIld the quill hygrometer of theAcademy of Manheina at +7°*
ExperimenzsiN° 3 4 S atad 6.
PuttiIag both the inRrumelltS iIltO naeltiIlg iceg I let them :remain there till the mercury ill ttle-illcloWed thermometers reIled at the poirvt ot, that is to fay till they had acquired -exa2ly the tempera;ture of fleezing water or meltirlg ice, alld then taking thenz out of the ice I plullged them fuddetlly into a large veXel of boiling waterS and obServed the tinwe required for the mercury to rife in the thermometers frotn ten degrees to ten degreesS from oO t:o So° taking care to keep the srate corRalltly boiling during the whole of this time, and taking
care alfo to keep the illArumetlts immerSed to the fame depth, -that is to fayX juR fo deep- that the point o° of the itlelofed thermonzeter svas everi with the furfiace of the water.
Thefe expe^itnents I repeated twice svith the utlnoR care!
atad the followillg table g;ives thc refllt of tllemt
Vti LX\Ie w 4
} Sp ' L tS
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X 2 o 54 70 o 58 X s 60 I I7 I 18 30 I 46 1 37 4C) 2 5 2 6 3° 3 14 3 10 o 5 4A 5 59 IO
Nct obierved. Not obierved o
-* - - w-
TiIne elapied.. n
- < Heat 1oR,
:F; N° g Exp N° X o.
......... .
80° A1* S. M. S
: 0 33 ° 33 7Q ° 39 ° 34 60
, o 4d, o 44 50
O 55 55 4° I I7 I IS 30
s X 57 I 57 ro 3 44 3 A° I O
40 IO Not obferved. o
+ \ 1 v , ; . ; W b , X: *, 8 _ :! .. ; 0 \ f > t s; W * t .-_wX.+ ti r. ;GF
L8erzzzetts upon HeazO z8;3 equal, the ;tltenfity of the <comtnunicationiis as t1At titnes lnverfely.
In thefe experiments the heat paCed through the fulroXtldil meditlm izito the bull) of the tllelXmometer: itl order to reverfe the experiment, alld luake the heat pafs out of the tilerrno- meter, I put the inLtrumetlts into boiling vater, atld let then remaial thertill till they had acquired the temperature of tl}e waters that is to IltyX till the mercury in the illclofed therno- xzleters Rood at 80°; and then, takiltlg them out of the boiling water, I plunged tllem fuddellly into a mixture of uTater and pounded ice,-alld lnovitlg them al)out continually in tlis mixF ture, I obferved the times employeel in coolifltlg as fbllovvs.
Cherfnoo)eter No I. Surrollnded by a i'orricclliar sacvx4m. aZen ovz of boiZing waarX v7wd jslzzgged
i?to freezing water. |
ChernsotneteriNo 2 : - Surroundcd lDy air.
Cakez out of boilitJg qaxer, vX plZaged z#to freeSing Water
Totat time of cooling from So° to I0°e Me S,
InExp.N°7.=16 4 F InExp*N°8.=16 s6
-
Mediu m=X6 Io
Total time of coollIlg Som SO° tct 3EC>9e M. S.
s
In Exp. No 9* =9 49 _ . n rlvhxp. > l>)*=9 4 i r k
MedJum = 9 45
y p p 2
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Surrollnded by air. HeatedSto 80°> vxd J4zwJ9ended ia the opezo
cxir vrm to I 6O.
, i M
- ^ .
Szr 13 E NJ A WiX I N rSoMP SON s
By thele experttuetlts it appears tllat rlle co1wduRilog po^7er- f air is to thclt of t}Xe lflo1^ricelllatl vacuum as 9Ww to x6X itlverfely, or as t oss to So3.
To detet^mitle svhether tEae fatne lanv would llold good svI1e the heated rllel tuonletet^59 illReadof l)ei1lg plunged into freez
g wrater9 rere fuSeled to cool in the open air I made tile followig experilnents. The thermometers N° I. allcR N° 2. I)eing agaitl heated in boilirag waterX as in the laI} experimentss I took them otlt of the- water, allel fufpersded thern in the middle of a large roomv svhere the air (which appeared to lze perfeEtly at reR the !windaurs atld doors beitlg all {hut) was warm to the x 6th degree of REAUMUR'S thertuometer7 atld the times of coolitlg svere obfervel as follows.
i (Exp. N° 1 I .) Thermometer N° I.
itirrollnded by a 'rorrice! l xarl vacilum. tHeatecS ta 80o aX2d j?zlpendeX in the opea t zir woB,rm f o I 6°.
Time elapiecl.
MX S. Not obServed;*
44
8
+ 16 _
] O I 2 -tota
Heat 1(30i, 80°- -
cz 7o 6c) 5o q.o
3o
1 time employed
rF;me elapfed. -
Ad1. S. Not obSelvei;
o 5I I 5
34
I
Heat lo.
8Oo
.
7o 60 5 4 20
6 s 1-stot:al t;Ine
ill coolint, from 7 of] to 30t O in cooting from 7 OQ t0 30°.
Here the diffieretlce itl the condud:ting powers of air and of the Torricvellian vaconm appears to lJe nearly the fame as in the foregoiIlg experimelats9 beirlg as 6TT to Ioo illverfelyS or ^as Iooo to 6eS I could nov obServe the tme of coolillg from
x 8OO
employed
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Bsperinzerzls gton HeatF 285 Soo to 705 beilig at that time buEied in-fiufpending the infiruments
As it-mightapozlzly be obje-Eted to theconclufiolls dravera Dom thefe experiments that9 notwithfianding all the care that was taken in the coIlIlruEtitlg of the tz^70 inLtruments made uSe of that they thould be perfeAly alike, yet they might iI1 reality be fo far diffieretlt, either itl ihape or fize as to occa Elon a very fenf1ble error in the- refult of the experiments; to remove theITe doubts I made the follosving experiments.
In the ulorning towards eleven o'clock, the weathe-r being remarkal)ly fille5 the mercury ill the barometer Itatlditlg at z7 inches I I 1ilReS5 RESAUMUR'S thermometer at ISOX and the hye grometer at 47°S I repeated the eXPerimeI1t N° 3. (Of heating tlle thernuometer N° . iIl lDoiling Waters &c.) atld imme- diately afterwards openil:lg the cylinder colltaining the thermo
ter Gt its upper etld5 where it had been fealedS and letting the air into itS I re-Sealed it hermetically, and repeated the ex- periment again s^7ith the fame inRrumetlt, the thermometer beitlg now furrounded with air, llke tEle thermometer N° z.
The refult of thefe experiments, which tnay be feen ill the following tableS Ihews evidently, that the error ari&ng from the diSeretlce of the {hapes o-r dimenfions of the two inIlru- ments ial queRlon vas lncorlfiderablea if not totally imper ceptil31et
xP%;
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Its bull) half ta inch al dia- ;-rneter {hut vlp irl tlle $etlter of a g;lafs ;lobe Is illch in dia- tneters voided of ;?sr, atld her- tnetica]ly fealecl.
faken oiat nf frerSt'ng water,
nd plzgnged to bsili, water.
Time elapfed. iSeat acquired. , ,, }, . 0 4 t O
A1. sSs-., O
q 55 lo ° 55 2° I- 7 3° I fS 4Q ; I 29 SQ
Z 2 60
3 21 70 I 3 44 8-
F. . ^ . ..
24 48 = total time of heating frorn oO to 80° Tota1 titne fi-om oO to 70O=
I I o 4"
Che tne Chermometer (N° I-.)
The glafs globe, cotlStaillixlg the bulb of the thermorneterj being; nowJilZed tvizh air and hermetically fealed. -
Ca-ken 0u of freez.ing water, agd plusged into bozliag water.
Time e-lap-fcd. Heat ac-quired. .. Oo
Mb S. 0 0 32 0 32 X0 0 43 30
5 4 ° 1 I \ 50 ;
. . I 24 60 z 38 70
10 25 80 <, n.
[ I8 5 :_ total titne of heatitlg from Q° to 80°. Total time from o° to 70°=
7' 40" r
-- It appearsX tllerefore, from thefe experiments, -that the con;- duEtitlg ponver of cotnmon atmofpheric air is to that Qf the Torricellian vacuum as 74 to 1 1T4w inverfely, or as looo to -boz; which differs but very little from the refult of a11 the foregoing experilnents.
NotwithRaluding that it appeared from the refult of theSe laR experiments, that any difference there might poilbly fhave been in the proportions or dimenfions of the inflruments .5° I. and N° * could hardly have produced any fenrlble error
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ill the refult of the experimelltS in quetlioll; t was ivilliilag}
however, to fee how far any confiderable alteratiotls of Eze ia the illfirutnent wvould affed:t the experitnent: I therefiore pro- vided myfelf svith ataother inRrumetlt? thich I lhall call fbar- someter N° 3. different from thoSe already deScribed itl filze,
and a little different in its conRrud:tiotl, The bulJb of the thermometer uras of the fame form alld
fize as ill the infiruments N° I. and N° ;2 that is to fay, it was- globular, and half an inch in diameter; but the glafs globe, in the cerlter of which it was confined, was much largers leing 3 illches 72 lines in diamet-er; and the bore of the tube of the thermometer was muc-h finer, arld cotlfequelltly its length, and the divifions of its fcale xrere greater. Tlle divifions we-re marked upon the tube with- threads of filk of differellt colours at every tetlth- degree, from o° to 8o°, as in the before-lnen tioned inAruments. The tube or cylillder belollging to the glaEs globe sras 8 lines in diamerer a little longer thall tlle tube of the thDertnometer and perfeAly cylindrical wfrom itst upper end to its Jundion with the globes beitlg without any choak; the thermometer beillg confixwed in the cetlter of the globe by a different contrivanceX which was as- follows Tc) the opening of the cy3itlder was fitted a Ropple of dry woody covered with a coat or hard varrliSh-, through tla;e cerlter or asis o£ which paXed the end of the tube of the thermometer* this colzfined the tube in the axis of the cylinaler at its upper end To confirle it at its lower end, there sz7as fitted to it a fmall Reel fprillg, a little below the pOillt 0°; which, being conEned round the tube of the thermometerX had thtee elaIlic points progeding outwards which preIElng agairiR the inElde of the cylinder? confiIled the thermometer in its placea The total lexagtEl of this inItrument from the bottom of the globe
tO
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to the vlpper elld of the cylinder, was 1 8 itlches atld tlle freez illg pO;llt UpOll the thermometer i11 about 3 inches a-bove the bulb; conCequently it lay about I2 inch above the jund:tioa of the cylinder with the glote, wwhen the thermometer was confiled ill its place the center of ts bulb coiIlciditlg urith nt:he celter of the glol)e Through the Itopplo s^7hich cloSed the elld of the cylitlder palEed tsvo W;nall glafs tubes} about a line iol dianzeter, which beillg about a line longer than the Ropple were Itcapped up occafionally with fmall Ropples fitted to tEweir 13ores. tRheSe tubes (which were fitted exadtly in the holes bored ill the great dopple of the cylinder to- receive themt arwd fixed 1ta tlheir places with cement) ferved to collvey air, or any other fluid, into the glafs ball, withoit being uIlder a laeceflity of removing the Ilopple clofiilg the end of the cylinder X svhich< ill order to prevellt the pofi-tion of the :tElertnotneter fiom beingF eatiIy derangedt vas cernented in its place.
I have been the more particular in tshe defcription of theSe infiruinetlts as I CQtlCeiVe it abSolutely lleceXary to have a perfeA idea -of them iIl order to itldgse of the experiments made witla them.
W;th theo iIlfl{lllmellt laR rdefcribed (svlaich I have called Shermomerer N° 3.) I made the follossrinp; experlment. It-was upon tlle I8tll of July 1aR, in the afternoon the weather saZ riabIeS aItcrnate clouds and furl-lhille, wind Ilrong at S¢Eo with now aa;ld tllen a fprinkling of rain; barometer at z7 illChOS IO-m lines tilerrnometer at IS°+, atld hygromerer va riable fi:ozn 44 to extreme moiIlure
In order to compare the refult of -the experimetlt made svith ttliS thermotneter svith thofe made with tne thermotneter NO z. 1: have in tlle fol}owillg tablefi placed tElefe e:sperilueiat-s by the Iide of eacll othert
(Exp
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o - o 38 20 <) 54 3° o 51 4° . 0 I 7 5° I 28 - 60 2 28 : 70 9 ° 80
/ - .
I6 59- total time of , , . N J heating from o° tc) 8o.
Time from o" to 7 o° 7 ' 59".
Exp. N° 4* w_
M. S. o So
o 35 0 4I ° 49 I I
I 24 2 45 9 IO
Exp*N 5
M. S. ° 3° o 37 o 4 o 53 ° 59 I 'zo
5
9 38 _
Medillmw
M. SF ,
o 3o Q 36
.
O At O SI
I O I 22
2 35 9 24
I6 55 17 3 Is 59 time of heating frolll o° to 8c>°,
rime hom o° to 70°=n' g3
If the agreefment of theSe experimel-lts vvith the thermone- -ters 1!J°-^Zv Xatad N° 3. filrprifed me, I was ilot lefs lilrprifed with their difagreemetltlll the experimetaLt svlcla followsO
Experiznent P;° r-6.
- Takingithe tllermotneter N° 3. out of the-boiling svater, X ammediatoly frIIbended it in tize middle of a large rooms where the airS which was quier, lladl the tempelature of ,;183,W SR. alld obServed the times of -cotlitzg; -as follovnrs>4
x-OLo aLXX5tIo ,'''Tllme
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9 55 totaltitne of coolillg fron-s80° to 3O°Xh0 Titne from 70Q to no°=8/O"; but in theesperimentW
SX. svith the thertnorIleter N° 2. the time emplbyed in moling-: :from to° to 30° svas ollly 6 lt/t0-- Iw thsexperitnellt, with the thermometer N° 3* the titne eruployed n cooling from 6O° to noo ssas 7t 48/ 9 I)ut itl the alsove-mentioned experimelltX with-- the ther£nometer NO it sras otaly 3X zo/. It Is trueX the air o£: the tooxz was fomesxthalDcDoler wvhP;0</the fbrmer experiment vas-made thatl svhen this latter sras made svith -the thermoo meter No 3t; but-^ this clifferet<ce ofs teruperatlreX lv1chS wa-s
eIlly z-oX (in tlle fbrluer caGe the thernometer ill the roorn Stalld-ing at I-6°, and in the lattel at I-8°4) certainly could l-aot have occafionetR the sshole of tIwe amareat difEcret1ce in tht reftllts of the experirnents
Does ait rective- heat more readitly tTian it parts sstith it > This is a quefiiot} highly defervln2)> of furtSes illveRigatiotz ,! and I
«all not f-ti to ginte it a fulI-examinatioll ill the conMe of Anzy projeEted irlquiries X lout leavtug it for the prelEllt, I Ihall proceed to give an aceount of t}ze tsperimetlts which I have already ^made $*
1t
$ -Concewing it t4 be a Rep of. confiderable -importaoce towards com*ang at a
filrther.
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E^pertmenzs tpX- Het. -Z<r Irt hating beell my ittentioll fron the bqgirlnitg to examitle
the conduaillg ponsers of the artifivlal airs or gaSesX the. tlaertnotnerer
Alrther-knowledge of the natur of I1eat, to aiertaxnX lJy intlibuta1oic evidoce: its pafEage through the torricellian vacullln, alld to deterllliLle, Witil 2S much precifilon as poilLJle, the law of .its nlotioL3s in t} at bedium; -and being appre- henfive that doubts might arife with refped to tEle experiments before de{bribed,,
on account of thescontaA of the tubes fofSthe incloSed thermometers in tl-le
infirtlments made uSe of with the containing glafs globes, or rather with theil cylirldets; by which means it migllt I)e fusfpeEted, that a certain qllantitr, if.n(st
all the heat acqvlired, might poflibly be Jcommunicated*:: to put this matter
-beyond all doubt, I luade the followilzg experiment.
In the middlc-of a glaEs bocly.9 of a pear-like forn, about*8 inches long, and
n3 irlches in its greateR diametel, I fuEpellded a fmall mercu;ial theralometer, 32 iaches loulg by a Ene thread of filk, iIl f<eh a manner that ntithel the bulb of
the thermomete-r? nor its tllbe, touched the contaitaing glafs hedy tn anypAt+te
1 he -tube of the thermometer was gradllated, and laIked vvith fine.thrsads.of I11t Qf diXerent colours lsound round it as .in tIle thermomerers belonging to the
other inIlruments already defcribed; antl the therinon eter was fufpended in its place-by means af a fmall fieel fpring, to which the exld of the thread of filk
which heId ahe thermometelz being attached, it (the fprang) was forced into R
fmall globular protuberance or cavity, blown in the upper extremity of the glaf$
bodaT, abollt half an inch in diamettr, w}were the fprirlg remaining, the-therino-
meter necelEarily remaitled fufpended in the axts of the glaEs body. TheIbe wad
arl opening at- the bottom of the glafs body, throllgh which the thermometer was
introduced; and a barometrical tube being folslercd to this opening, the infilde o£ the glafs body was voIded of air.by mealls of merctwly; and this openxng being aftelwards fealed herlnetically, and the;'Darometrical tul)e being tal{en away, th: therlnometer was left fufpended in a Torricellian.;vacllum.
111 this itlItrllmctlt7 as the inclofed thermometer did not touch the coutainilug glafs body ill any part, on the contrary, being diIta11t from its inter.nal filrface an snch or more in every part, it is clear, that whatever heat pafIed in:to or ogt of the -thtrmometer muft have pafled zhrovgZ the furrounding Torreicellaarl vacullm: fo1 at cannot be flppofed, that the fine -thread of filka by which the ther£xlometer
was fufpended7 was capable of condudting any heat at all, or at leaR any fenElble quan;tity I therefore flattered myfelE with hopes of I)eing able,, with thB
- Qq - afEftance
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tBermo-metEer- N° 3-. was conItruacd withs t vieW tb thoSb tpe- fiments n andi hurllig now pro-vided 3nyfe d wlth l o-&k- of Klafef diSrent klnds of airi I begaIi w-ith2hed airSr with which, by:<
. .
aS;Rance of > this inflrument, to etermine pifitivet-y wwtth-- regerd to - thbipffige« of heat- an the Torrlceltian vacullm: and this, I th-5ilk- I h:ave dont notwitEind}ng>- t-hat an *ln-fort-llt}ate ac-cidenst ptlt it Oltt Of Sy pOWe to- ).ni it ti46m:tets fo:. hr as I intended
Thisv ilaRl lihient being teArto a fusal:l -hnd wi bot of totdt ins f bb as m-anner; that the glafs bo- remained; in a perpend-kculAr SuatroF; Ii piaced it i:n my room9; 13y the fide of another inclo@<:l thelmometer (N° 2.), wthi-ch was lirinde-d bar air, aiad ob$erved thXefReR of the valti-ation} of he-at in the atnrofherei 1 foo£t-;
.dikovered, by the aoron of: t-he merellry tm the iticlQcY therrnometer,. that th$.- h<eat paffed throlxgIl tlle Tort-icellian- vacuun1; but it appeted plainly from the; ilgg.illlgS O--r- great iafehflbility of sthe thrmomEer. t hat the; it--- pXtid tt;kJ. nlllch- greater difficulty in this m.e-¢lium than in commion air. I no:w pli^n>ted botS the thermorneters into a blIcket of cold water; andt I oSferted that the m:erctlrF iii the thermometer furrot1ndecl by atr defceIlded nltich: Her that that. i-n the- ttierxnometer furroun-ded lDy the T.olriceilian vaculllne I toolt tim out o£ the £old water, and pl<rlged them ixwto a veel cwf it-werl (-hasxng rle cortsvtiW1enciesi at hand to repeat- the expexltnent in form withg the;eKeZlng aizil with-the boiling mater)> and tlic therinometer fiXxloutlcled bf ffie lDorricell;lan vacullm appsare 5:lUl to be much nwore infenfilbie or {lilggif11 t}ann t-htt -XinwtoUtlded by a}}r
WIlelitlinlsivere quitefucieht teconvintemeoffthepafige;ofheind in tht ttorricellini:! siacuurn, atldf alfo of the greater difficulty^- of i-ts; pafl age ins that;; Jncdt.lln tllan ;n comrrioru a;r; but szot fatzisSed: t¢ r;eR rtly inquirics herd, letook tlle firR opporttlrlity that oSered, at1d it: qilf to repeat ti: tspe-riments which a had before made with-the inRruments g I and NQ 2. I plU£1gEdothtiso iniRrUa meI}t lnto freextrig waterX wllere I let- it reMail: tll the merellry: n the incloSed thermonleter had cleScended::to o9, whenX taking st out of::the heezingwaters I . pltlxaged it {SiddenEy ilatowa v eItel of; boil4in-g warerf . a2il tprepAredt nSyilf to obReisve the afcent of t-lle-ffiercuy is} the incloSed therniom-ever as i-n the:fore;going experlX
. \
ments; but nafortunately the mornent the tenidS of the gla- boZ tDuchea the boiling water, it cxiacltetl Witil tk beat at the- point sv--here- it had bech he;rmdically Sealed arud tlie water ruRling into tht boe, :loi-}- th experisfent :- and I h:ave- not filace-- liad an opportusiity of provldlng nny-seW vvltli- armtie1 iSri-Snte to
. repeat 1t. meallS
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- EwSier+nents skpot Raat z93 D-a&705 watYer I filled---the- glebe; and: cylinde:r containing ie thermometer ;* and Roppi*z<wg{ up theEXtvVo holes lt1 tho great Ilopr ple - clo-forlg theS elld- o-f the \ Clind400 I- e%pofed/ vlie inflrument il X freezing-water till: the- mercu-ry- in-the itlclofedw th-ermotneter hacl defcended- to o°; -whfell7 taltillg it outR of the freezitlg raters: t plut3ged itX illtO a lage-veflel of :bellitIg water>^X- and prepfared
myfelE to obServe the tin<es of flleatitlgsi atinf the former ca-IEs }.
but ani accident happelie-d, w-hich fucldeNlyw putFa ftop to tht experitne-llt. Itumediately upon pltlugiog the inflrumellt :snta the boilirig water, t:l3e lnefr-curg heptl to rife ilw/the t-hermometer-* xv;t11 fuch u£lcommor- cBleritt, tlait- iit hacl-; paffed the firflc diviw ; flon upon ther ttlbe (which marldvthet tot1wtdegltee- accorcli<1lg; tot ReAuMoR's- fcale) bef-ore l svasf tware of its bei-tlg - yet ill motiotl ; at-ld: havin,C, thus mi>ed;the oppOl-tUEtlity of c>bSer-vi]g tIle titne elap:fed; w:lata: tlle: mercury arrived- at that pfoint: i vvas- preparitlg to- olaferve i£s 03Fw0>05! the Xnext V wh-en- a11 of a- fuddet1 the Ropple- clofin-g th-e- et1d of tlle cfinder- sras blowt1; vlp the chimtiey sv-ith a greatiexplofiotl, atld :the thertnotnereryg hich, beillt; cemetlted to tt lly its--tube> srras tXakels alorlg svit
xt, and was ljrokell to piecesn tld deErged iIl its-fall.> This uli-rtu-nate txperiiment>; thoughfit pult a t for the;
tiine to-t-he illquiries propoIidS opened theX w;ay to other reZ fiarches not:lefs iLuterefRing. Su@eAing that the exploElon was-< tccafiiolled by tlwe- rarefahiotz- of 7: the: water: dich rernain@- attached to- the ;tlf1ele of the glob-e and cylinde^r after the ope- ratioil of filEtlg the£n withV fised air; and thitlkit1-g it^mor¢^
*thatl proba-13leS that the uncoulmo:n ce-lerity, with which-the mercury rofe itA -the--thertuorneterS was- principally owit3g tO-;
thx falne caufe; I>.-watsnledto ex5arni-ile the COiUaillg: pOWOttO
tW0S.aZi+, Q1 Wair faWrated¢XvSith svater<. .
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^ For this expelAitnent I provided lnyfeif with a laesr ther1z3oZ meter 3 *+-* the bulb of wili¢l? being zof the famge irnz as thei already defctibed tui; globular) sras; alSo-of the- rame flze,-- or half an incll itl -dialneter To receive this therin-otnet= ;azglafsicylitlder watpronridedg -8 lil<es ill diameter, alld alsout 4 illches lotlg aIad tertnilslated at eIle end by a globe tX inch in diameter 1t1 tlae center of this Fglobe the lJulb of the ther- mometer wras cotlfinedS ly lu-ns -of the llopple<svhich clofed- the- ied of the cylinder; svhich itoppleX being laear z inches lo1lgf re- ctived the end of the tube of the thermorneter illtO a ho:le bored tlaroughXlts cetlter or asis, and confil}ed the tilermometer ill its placg -withou-t the afiillatace o:f ally otiler apparatus.. ¢ Tllrough th-is £}opple -two other ftnall holes were bored, and lille(l with ;thin.gRaSs ttlbes as ill the thermometer N° 3* opening a paS- -fage*;nto the cylinder which holes welXe occaft:-lotlally itopped up with i:ome Ropples of cork, but tor preYent accidetwes, - ich as I had before experietlced froln an ex-plofion-, great care wa-s -taketl not to preii thefe fiopples irlto their places witll alky COll-
-flderable forceX that th-ey might the more cafity be I)10\VI1; out by aly cotlflderable eirt of -the colafiXacd aiz*¢
Though ein -thxs itlRrument the ;thermometer- was not alto- gether fo Ready;in its place asain the -;thertutm-eters N° t. :A4 2
alld- N° 3. the claflicity of Fthe tul)e alld the weight of the mercury in the bulb d the thermorneter, < occaE1olling a fm-all- vibration or tremluling of-tthze&thermometer upon any fudd-e motionortjar;-yet$I preirred-thistnethodsto the others, ot-l a£count of the;lower part of this ttherluometer being itltirely free, +or fufpetlded in fuch a matltacr as not to touch s or whave a;nyicotumunication with the lower part of the cylitlder or --the -globe: for though therquantity of heat -trec-eived by the- <tabs of the tbermometer at its colltaA w;th-the cylinder at its
choaks9
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Surro-unded - ly air rendered as tno as poSlble l;)y wettitlg the: ;itlflde of the\ cylinder and globe with water.
Cafien ot of Jreezxng quaerX and planged inza boilxg twfaer.
,, , :^ Ih. , _ r , ,, . , . .5. } . . | 6 - _ t ^> L w A
Experxmeegfs upan HewtlQ 29-5-
thoaks,- in the itlfiruments N° I and N3 2. or with the brallches of the lleel fpr;tlg in N° 3. al;ld from theaace comrxlu- micatedto the l:)ulb, muI} havc been exceedingly ftnall; yet I xvas defirous to prevent ev¢ts that and every otlzer poffilble crror or -in-accuracy7 however iTna11} that might ariSei.
Does humidity augment the conduEtitlg povrer of air > . .
To determine this quelliotwi I made thc iliowingtexper* lnentsX the weather inciv}g- clear atld firles the tnercu-ry itl the barornete.r *allding at 37 inches 8>- litw¢s,i the thermometer at X 9° alld the hygrometer at 44s°*
(fSxp. Ao x7 ) - Ske^rzomeZer NO 4^
Surroutaded Ly aip dry to the 44th degree of tlle kfuill hy- ,ronleter of the atihelm Academy % TSakeg ovz of fiseezzg wter, and plvagefX int- boilang -wter
Time elaplUd. eat acqTlired Time elapid EIeat acWquir O
Q s Me S qD (3 6 1 O
O 4 t0
O 9 40 tO 1 8
i t3 2 6 < 6C i
° 43- - -7 7 4S - 8
__ _
I 5t-total timze heating Scsm oo to 70t .
ed,
;}- At sF o
- 0 34 t° O 39 2:)
ffi ° 44 o Ri - o 5t 4° X 6 5°
) ; ,,#
I 3S so >< 2 4° 70
not obIervedO 80 . . ,. . . ......................... ;
<5 8, 9 = total titne of heating fiom rJo to ^-o°*
of b:
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* 4 k . X k i s x k _ R 4 ., ,, , _ t v , ,. . s . * s < = i 4 * i * B- * a t- r$- , . . 4
Sr -BEN3 AMIN tHOM;P$:ONS .
aor 9
Ftotn thefe experiments it appear$, that the <ctI4)U-&it
possei: o£- air is YCley LIlUCh iX5rtae w humiditJ To ke W the i;inae lkeilt wouXld obaln^-k-wietl ffie;^¢Xp;crimellt--wasm- verSed -I--llo-w-tok the the;rmomear with- wthexoH dxr:out of the boililig water, alld plunged it iinto fEeezing -ter; -a;tld movitlg it about cotltinually fiom place to place in the freezillg waver, I obServed fthe times o-f-!coolillg, at -Set down ni- the bIIowilzg table 19. -13 -To colzi?a-m -the-tefult;of-this experis ment -svith thowSe made with dry an, I have placed orl one fide in the foliowirg;-table the experimellt in queRion!, aand on the other {ide tlle experimetit 1t 9-* made w--th;;tlie therrno-
.... . . 1s .
meter L) o 3.
(E;#xp. NQ 9.) : TerwoaoXet¢r-BJ° 4*
Stlrroundecl 18 sn ver qZken ot sf boiltig q ter,
and plza>ged ;Ntofzezzag wter * _ _- t; tj
Tilne elapfal. + Heat loR. .t . . *n
g 4 i fu¢Oo
Mv SQ ,4)
'O '4 S fe,< > ;sIdJ %t
.sO $0
-Q :; 3 4O
I -37r
-3 3 -kO . .
- ^-4 I O
..,
^9 8>;<-ztotal tivue of conling fronz 80 to O o*
(Exp N° I 0^) iAher7W>onvweter No -2.
S!lrrou.lwded by dry ar. -
,-Vz 1 r * * :
aten ovz ff tofig waer d planged ssto freezxng fwater
Wiale ela}ied. }Ieat toRX '' 80°
M. S. o2
t 33 iO ° 34 6o t 44 59 }3 55 4° , l g i3O
.
I 57 2
J S . so , .
9 ] Z total tlme of cooling fitln 8Oo to 10°*
- Thougll- theediffere-rlce of the whole times of cooling fFotn Bo° to Io°in thefe two ex3perimetlts appears to have lzeen very
S MmallX,
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X711? yet Zthe fdiffierence of the times;;taken up t)y Tl1G firk t..wet,.lty or.thirty,<3egreestfrorn,..the 'ho;1illg poillt.is steryrew
markable al}d Ihows with how much 8,-reater facilityiheat- l paSs in moiR air than in dry air. Even the i[lowtlefs with whlch the mercury Sin the thermotneter NO 4* deScended :in this ewesriment firom the 3othto the 2sth} and fromsthe zoth tQ the xoth degree, I attribute iri forne meafure to tlle great conduEtionag power of the =nzoiR air witll whish it was: I;Xr- rounded; zEor the cylinder containing the thermometer and rlle
moiR air1s being not;.wholly IBbmerged in the ofreezing water, thXat tprt qf -ittwhitch remaitled out of the water was neceICarily
fursrour¢ded by ithe air of the ati:nofphere-; whrich being much warmer thatl the watera communtcated of its heat; to fhe tglaSs;
which-pagillg fioni thence-i1]to the coutained moiS sir as foon ashthat air becameicolder than the exteMrnal atr was
t4ropgh tbatDrsn5ediulfn,^com=nunicated tothe}bulb of-the-oyinZ ciored tllermometery which prevetlted its cooling Ib faR as it quiKd-othxrwiSe hoave doIae. But whn the sreather;becomes cold, tI proWpoSe sto4 repeat fthis experiment with vari-ations, in $ch a+-matlner as to put the matter beyond alXl- doubt. ;:II1 the mean titne: I;cannot help obServingX with what infitaite wiSdom ad $o4rXefs Di+7ine Provsidcnce appqars to have guarded us
agXnA the evii efifts of exceffilve heat and cold ila-the atmo- fphere; for if it were poIE1ble for the aiNr to Ive equalltr damp
durtaXg the -+Severe cold of the winter months as it:^fometitnes is
ill Xmmer, its £ondutRing power?>aild conSequetwtlyoits apparent mldne> whell appliJed to our bodies, would be ib much in- creaSed, ley fuch al adtditionalb dqgree of moiRure, that- it
w<ould bqcowne q>: intolberable;i but,\ happily for usX it5
pqwer Xto hold water infolution is diminiffied and vvith it-its +
pawcr to rob ps of our animal heat91in proportiotl as its
vOL. LXXVI. R r coldneX
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coldlzefb is itlcreafed Every body ktlows hos5r very dii:agreeable a very tnoderate degree of cold is when the air is very darnp,
. .
and from heluce it appearsg why the tll>ermometer is not always a juiR meafure of the apparent or fetlfible heat of the atmo- fphere If colds or catarrhs are occaiiolled by our bodies beillg Iobled of: our alaimal heatS the reafon is plain why thofe dif- orders prevall moil durillg the cold autumllal raitlS, and upon the breaki3)g up of the froR irl the fprillg It is likewife plaiIl from whence it is that neeping in damp beds and inhabiting damp houIes, is fo very dangereus; and- why the evelling air is*: fo pernicious in futnmer alld in autumn, and why it is not fo durillg the hard fiXolls of witlter. It has puz:zle-d matly- very able philoISophers and phyEicians to accourlt for the mallner ii< which the ext-taordinary degree or rather quantgty of heat is g!e}<erated which an animal body is fuppofed -to loSe when ex-
. . .
poSed to the cold of winter above what it comtnunicates to .. . . , S . the furroulldillg atmofphere Sin warn fun:lmer weather; 1)ut is it taot more thall probable, that the diSerence of the qualltities of heatS aEtually lofl: or cotnmunicatedS is illfitlitely lefs thae what they lzave imagilledW iTheSe illquiries are certainly very
terefiilags alld they are undoulJtedly awithin the reach of well contrived aIld svell corldtld:ed experitnents But taking my leave for the prefent of this curious fulejed of inveRiga- tioll, I haReil to the fequel of tny experitnents.
Filldilat,- fo great ? diffelence in the cotlduEtillg powers of corntnon air atld Qf the Torricellian vacuum I wa-s led to cxarwitle tlle condudillg powers of cornmons air of diiSerellt degrees of dellrltyO Far this experiment I prepared the ther- tnolneter No 4. by flOppillg Up one of the Emall glaEs tubes paS-Ellg tlarouglo the :Ropple, and openinga paffage into- the cylinder, alld by fitting a valve to tlle ¢external overture of the
othero
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Esteriments- 2pon zea 299 other. The infl;ru m-ent, tlfus prepared, bestlg put ullder tlle receiver of alu air-ptmmp, the air laffed freely out of tlat globe alud cylinder Upon workitlg the machitle but tile valve-- above defcribed prevellted itS rCtUrll UpOll letting air into rlle receiver. The gage of the ai«r-pulnp ffiowed the degree cf rarity of tlze air ullder the receizrer and confequently of that filliIlg the -glol)e and cylillder, -atld immediately futroundirlg the thermo- meter.
With this inIlrument, the weather being clear and fiXle, the mercury inthebarometerfl:allding at 27 inches 9 litles, the thermometer xat X 5° and the -hygrometer at 47°, T made the- fol- * -
ONVlllg experlmellts.
r (Exp.N'9\2{.)
Thermomerer N° 4. Surrounded by alr rare-
fied by pumping till the bal ometer-gage Itood at 6 inches Il2 lines. - - lken ozzt of freczizJg wa
ter, anXpinged itto boilirg
- B (ExpaNozoe) j
thurnowet(r N° 4. Sul l ounded by common
air, barometer Randing at 27 inches g lines.
i . .
farken oat of frgerirg *vve ter, and plxrsged irzto bozltag water. _
,,, _. , .
- Time Heat - clapfed acquired.
(Exp. N° 22*) - i2vermomefer No 4. Sllrrounded by air rare-
fied by pUSpilig till the Liarometer-gage Rood Et x inch z lines Wa4cg 01vt; of fsXee zi^g wa
eer3 arzaf jplvaged into boikistg water wter
: , _ _* e; ,,,
Ti-lne: ¢ < : Heat acqu; red .
Time-: Heat elap0ed. acquired.
o°
I \ A1. Sv o
o 29 xo cz 36 ro o 49 3° I } 40 I I \ 50 I 24 60 z 31 70
£1ot obferved 80-
7 5 1 = total time of [ heating from o° to 70°*
0o
M.S. ' - (, . O 3I 10 0 40 20 o 4t 3°
. .
. X 4 50 x 25 60 2 28 70
s0 x7 80 *
7 36=total time-of - heating from o° to 70°. _ o
elapfed. _*
M. S. o 3t
io 38
° 44- O 51
7
I I9
2 27 IO 2t
o
o
10
o
3c) o
3o 60 7o 80
7 37 total time of beating from o° to 70°.
- -
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lehe re$;A1t of thei experimeMs, I tonfbEs,i illrprlieid mAe not a little; lbut the dikovery of trutS beiiig the ble obje&- d my ignqiairies (ha57ing no: fivoiiritel theo? to deind) i-t- bring-s no diCappoitltment alonig with it> ulder whateveri usexpeEed Ihape it may appear. I hope that fiietller esxperi-ments mt lead to the difcovery of the cauId why there- ifs; IVi li*ttlEe difireitlce in the cotIduding; povrePs o-f Aair of ich tery diiEren-t 3igs df rarity7 -while there is fo great a diffierence -in tlle corlduNg powers of air, atid of the Torricellian tacuurn. At pr4tlt, I a11 not venture any coXe&tires UpOIl the i;bje&; 1jut in tM
mea-n time X dare to aSert, that the experlments 1 havs m-ade may be depellded on.
The timew of my flcay at Manheim bking expired (having? had the hollour to attehd thither his mofl: Serene HighteSs the EleEtor l'alatine Duke of BavariaS mf tnoR Graciou$ Ma-Rer, in his late jourtley), I was prevented from purfuiing: theIb in quiries further at that time, but I ihall not fail to recommene them the frlE leifure time I can find which I fincy will be about the beginning of the mollth of Novvember. In the -mesil
. . . .. . . . .
tilme, to enable rnyEelf to pur-fue thein with efNe£t-> I am tpariIlg neither labour nor expencve t-d provide a cizmI31et appa_ ratus nseceSary for my purpoSe; and liis EieEtoral Highnefi has b-ecl} gracioully pleaSed to order: M. ARTA;RIA (who is ill hisafervice) to conze to Munich Vto aIEzk me. With fuch a larron as }<is moI} Serene HighneIi, arld with :fuch ah- aElIlant 41 R rARIA, I ffiall go Otl ill my purfuits w1th chearfuluefs. Utould to God that nzy labours mig-he bE as tSeful to others as ttley will bse pleafant to me !
I f}-aX concIudfe ithis letter -wit-h ae -aee-nt :d ine ¢xperinaeilts I have made to det-rmirle the condudtiI3g powers
f
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Surrounded by water. zraken ovt of fir ezing Wtera a
pltged i boilzag to __ i _
takex i
- - i
Time elapid. w _e !
Exp.NZ4*- Exp.N°25, __ . __
r M * S * 3u S o O 5 0 5
- 0 4 o a 0 2- o -2
. . .
O 4 ° 5 ° 4 Q 45 °- ? -° 4 O I5 O 9
*
Not obSerwd o 58
l n l # : -
Experim{s upon Heat. 3ot . .
. . .
of water alid of tnercury; and with s tableX {howlug at one vsew the conduEting powers of all the- difEerent medium/s whtch Ii have exanined-.
tI-aving filled the glaEs globe inclofnWg the bulb of the ther meter N° 4. iRrft with water, and tthen with mercuryS I
nsladoe the following: experi.ments, to aCcertain the cotlduEting polwers of thoSe two fluids
(Exp. N° 24X!+ 25 and a6* Shermometer N° 4.
Surroun.ded by mercvvy. ot..of fre¢ming tuaterX a7ZG pXngeSl ito - - boilixg water
t
Exp,N°26. acquired
- O
M Sv
I
o 5 I0
O', S 2O . 4- 3°
.
0 5 40 0 7 scz o 8 60
O I4 7° Not obServed. 80
Time eIapid. Heat acquired.
- : K : M. S c,
Q I - I0 b' () b 2o
o 9 3 0 II 40 o s5 5t o 21 60 o 34 7°
- 2 I3 80 _
I 57 =total time of heat- ing from o° to 700.
tirnes 0 4I o 3i of heating from o° to 70t.
0 48=total
The total time-s of heatilag firom o° to yoo in the three ex- perimellts with luercury being 4t fecotlds 3T feconds7 and 48 fecollds, the meall of thefe times is 363- Secxds > alld as in the experimetlt with water the time employed inX acqlliring the fame degree of heat was I t 57/ _ I I 7 Seconds, it appears
from
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from thefe experimetuts, that the condu&-illfg power of memuX: tothatof svaters ullder -the circumIlallcesQdefcribed, isas36:XX to X X 7 iVnverfely, or as IOOO: to 3 I3.: tE Andf hence it --is plain: X
rhy lnercury appears-foX much:hotter, XallDd00:b much colder, to the touch than water, Xwhen in faR it is owf theXiime temperao :ture: t for the force or violellce of the IEntion-:of: bot or -coZd depellds llot itltirely upon ;the telnperature of Xthe bo0: exciting itl US thofefeniatiolls) oruponthedegree of heatitaftually poINefles, but upon the quantaty of heat it is capable-;o f commu-: nicatitlg to us,S for receivinrg -from uss in atly givell Ihort petfiod of time, or as the intetlfity of tlle conlm;unicatiotw; and thls depends itl a great meaftlre upon the conduEcillg powers of thg bodies il2 qUeflIO. i
The SenEation of hot is the entratlce of heat illtO our bodies; tllat of cold is izts exit X and svhatever contributes to facili-tate or accelerate tllis commutlication adds to the vioSence of the fellIition. And this is another proof that the thermometer cannot lte a juLE meaftlre of tl}eJ2nJ^ble lleat, or cold, exi{ling in bodies;- or rather, thatX the touch does ncst afford us a jufl: indication of their real temperatures! -
A_ a w
1 afvle
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Caken otct of,fi;eerixg qrater, and pl>ged ixfo boiliazg water.
, Time etapSed. i . w
5 CR k Z kl ;5 ; r 8 C * ;3 1 z e ° 5 Z X 7 |
. s * _- S zA,l_, . _
11 _ __ ' _ __ _ O0
M S. M S M. Se M. S. z M. S. M, S. M. S. O s o 52 0 3l o 3I ° 29 o 6 o s9 ° S IO
o 58 ° 4° o 38 O 36 ° 4 O 8 0 332 -- ro }
- I 3 - o 4I O 44 ° 49 0 5 t 9 o 3o
I X 8 ° 47 z o 5 I 1 X 0 9 o I I o - 43 4 I 25 s 4 I 7 X I O I8 O I5 O 5 5° I 58 I 25 t 19 I 24 t 26 0 2 I 0 631 60
3 9 < 2 28 a 27 z 3I ° 43 ° 34 o I232 7 I 57 - 0 I7 IO XI - 7 45 z I3 ° 5S 80
1O 53 7 36 7 37 7 5t I 5l 1 s7 o 3632 = to" tal tilnes of- beating from o° to 70°
_ I _ R. - | . ,
Expersznents upox tIev.
3°33 X T*atle- of tTle cond?XAing Powers of the utlder-mel}tionec
Med^ums, as-- determined by the foregoing experimetzts
In detetmining the relative conduAing posvers of thefe meZ diums, I have compared the times of the heating of the ther- morneters from o° to /o° illRead of takilog the whole times :from o° to 8O° oll account of the fmall variation ill the heat
r , ' g .
Of the t3oiling water ariflng from the variation of tlle weight of the atmofiphere, atld alfo otl account of the very Ilow m;oZ tion of the mercury betsveen the 70th and the 80th degreesaF and the difficulty of determinitlg the precife moment svhen the tnercury arrives at the 80th deglee.
Taxlng
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3rz4 Sir Bsltmrs THoxPSteN?S Eerxmen>, &c. Taking now the conduEting power tof mercury = tooo, tlle
conduditlgpowers of tllle other mediums as determined ly thefe experirnents? will be as fiollows, viz.
. . .
hIercury A - * I 005
;Moid air ^ ^ 3:3° . . . . ... .... .
Btaters v -* 3I3 ( olXmon atr denfty--br 8oT40tT
Rarefied airX denfity 4 * goTtj-63w
RarEed air, denSty--2lT 78 The Torricellian vacuum 55
. . .
Atid in-thefe proportions fare the quantities of heat wliicll tlleSe different mediums are cqpabletof tranXitting itl any- given time; and cotlfequently th¢Se numbefs exprefi the -relaw tive ble tesnperatures of the meidiu:ms, as well as their con dud:ting powers How far theferdecifions will hold good utlder a variatiotl of circumIlances experiment only can determinee This-is-=rtainly a fubjeR of inveRigation not leX -:curious itl stSelf tharl :it - is interefiing tQ mankind, atld I wiSh that wha-t --1 have done tnay itaduce others to turtletheir attetltion to this long negletRed field of experimental inquity. For my own part, I am determined not to quit-it
It1 tlle future profecutioll of theSe inquiriesX I do not mean to confine mySeif folely to the deterrnining of the coIwduEting powers of fluids; on the corlerary7 lids, and particularly fuch bodies as areimadeZ uSe of for- cloathing, svill be principd
. .
ibJeEts of my future experiuments. zI7have indeed already begBun thefe refearches alld have made ime progreSs in them; but I forbear- to anticipate a matter ?h:ich I tpropofe for ithe fubjeEt of a future communication
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