The Supposed Effect of Boiling upon Water, in Disposing It to Freeze More Readily,Ascertained by Experiments. By Joseph Black, M. D. Professor of Chemistry at Edinburgh, ina Letter to Sir John Pringle, Bart. P. R. S.Author(s): Joseph BlackSource: Philosophical Transactions (1683-1775), Vol. 65 (1775), pp. 124-128Published by: The Royal SocietyStable URL: http://www.jstor.org/stable/106184 .

Accessed: 18/05/2014 16:09

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 support@jstor.org.

.

The Royal Society is collaborating with JSTOR to digitize, preserve and extend access to PhilosophicalTransactions (1683-1775).

http://www.jstor.org

This content downloaded from 195.78.109.161 on Sun, 18 May 2014 16:09:56 PMAll use subject to JSTOR Terms and Conditions

[ I24 ]

XIII, IJhe /^poJ^ed EffeA of boiBixg vpon AYater, in d.ifipog it to freeve snore readily, aUtcertaned by Experiments ty Jofeph Blacks M. D. ProfeSor of ChemiJtty at Edin- burgha n a Letter b Sxr John PringleX Bart P. R. S

t0 SIR ,iQHN PRTNGLEX BART. P. R. S;*

iI)EAR SIR2 Edsnburghs Feb. T I s I 7 7 5* Redde, Febv 23> 55 ;rE ad lately one day of a calrn and

775 VV clearfro; aIldIimmediatelyfeized the opportunity, which I miXed b-eire2 to make fome experiments relative to the freesing of boiled water} X compariIbn with that of water not boiled I ordered fome water to be boiled in the tea kett}e four hours I then filled with it a Florentine flaSk, and immediately applyed fnow ta the flalk until I cooled it to 48° o£

.

FARRENH1:IT the temperature of fome unboiled water vwrhic:h fltood in my Rudy n a bottle; then putting four- ounces s3f boiled and four of the urlboiled water fepa- rately, intQ tWQ equal tea cupsl I expofed them on the outllde of a ngthwindow, where a thermometer pointed to z9°. The confequcace-was, that ice appeared firS upon the boiled water; and this, in feveral repetitions of the expersment, with the fame boiled wates; fome of

svhich

This content downloaded from 195.78.109.161 on Sun, 18 May 2014 16:09:56 PMAll use subject to JSTOR Terms and Conditions

t I25 3

which were made nme hours after it was poured out of the tea kettlet The length of time-whith intervetled between the firflc appearance of ice upon the two waters was different in the different experiments. One cauSe of this varxety was plainly a lrarsation of the temperature of the air, which became colder in the afternoon, and made the thermometer defcend gradually to 55°. Another cauSe ras the diIlurbance of the water; *rhen the un- beiled water was diRurbed now and then by WTing it gently with a quill tooth-pick, the ice was formed upon it as foon, or lrery nearly as foon, as upon the other; arld from vhat I faw, I have reafon to thialc, that were it to be fairred inceIfantly, provided at the fame time the ex- persment were made with quantities of water not much larger or deeper than thefe, it-would begin to freeze filll as fooIl. In one of thefe tnals, havitlg infpeEted my te-a CllpS when they had been an hour expofed, and finding ice upon the boiled water, and none upon the other,1 gently fcirred the boiled water with my tooth-pick, and faw immediately, under my eyeS fine feathers of ice formed-on its furface, which quickly encreafed in flze and number, until there was as much ice in this cap as n the other, and all of it fbuned in one minute of tim¢, or two at moR. And in the reR of the trtals, though the congelgion began in general later- irx the unboiled water thaxl ill the other; when it did begin in the foxmer the ice quickly encreafed fo as, in a very {hort time, to equal, or nearly equal in qllantityX that which had been formed more gradually in the boiled water. The opinion,

- S a therefore,

This content downloaded from 195.78.109.161 on Sun, 18 May 2014 16:09:56 PMAll use subject to JSTOR Terms and Conditions

[ tz6 ]

therefole, 'which I have fbrmed from urhat t havc ht- therto Seet. is that the boiled arld common water difEer fifom one another in this refpeEt; that whereas the com- nzon rate, when expofed in a Rate of tmnquillity to air that is a few degrees colder than the freezing points may eafily be woled to the degree o,f fuch atr and Rill conti-

ue perfE&ly fluid, provided it Rill remain undiRurbe-d-: the boiled water, on the contrary, canot be preferved fluid in thefe circtTmRances; but when cooled dowrl tcx

. .

the freezing point, if we attempt to mAe it n the leaR- colder, a part of it is immediately changed into-ice; after . . which, by the ccyntiIlued aAion of the oold air upa *, more sce is formed in it every moment, it} the whole of it be gradlllally congealed before it carx bewme as coM a;s the a;r that furrounds it. From this vcry it is eafzr to underRand^, why they find tt neceffiry to bell the water sn India,- in order- to obcain ice. the utmoR itl- tenfityof the cold Lwhich theycan obtain btal1 the meatls they employ, is pro?bably not greater thaFl 3t° or 3c>° of FAFxrENHEIT'S thermOmeter. Gommoxl water, left un- diieturbed, will eafily defcend ta this degmewbout fieev ing; and; if they have not the means of maklng st colder, may continue flnid for any ame, provided - it be- not dif- turbed * the refElgeraiing cauSes aftharpart ofthe worId- when they :have done fo much, haw done their utmalE, and can aEt no further uwn- the water. Be t}i cao£

happen to the boiled water; when the rePrigeraig caixfes have cooled it to 35a, the nextt thy pce, s to occafion in it the begxnning of xngelatffally sltile

the T

This content downloaded from 195.78.109.161 on Sun, 18 May 2014 16:09:56 PMAll use subject to JSTOR Terms and Conditions

[ . I«7 ]

the water is aftenrards gradually afl*uming the form of ice, we know, by 0 experience, that the temperature of it mufc remain at 3X°; it cannot be-made colder, fo long as any cofiderable part of it remains urIfrozen(F). The re- frigerating cauSes c.ontinue, therefore, to have power over it, and toaEt upon it, andwilI graduallychange thewhole into ice, if their adrion be contitlued fufficiently long..

The next objeEt of invefcigation may be the cauSe of this difference :beeween the boiled and the cmon water. In confidering this point, the following idea was fuggefced. As we know from experience, that by difrurbing common nrater, :we haRen the begirlnillg of its collgelation, or render it incapable of being cooletl below 3 z°, ^vithout being congealed; may not the only clifference bet^veen it and boiling water,:when they are; expofed together to a calm firoRy air, confiR in this clr- cumfrallce: that the boiled water is neceffirily fubjeEted to the aAion of a diIturbing cauSe, during the whole time of its expofure, which the other is not > One effieEt of boiling water longX is to expell the air which it natu- rally contains; as foon as it coolsS it begins to attraEt and abSorb air againX until it hath recoarered its former quan- tity; but this probably reqwlires a confiderable time. Du- ring the whole of this times the air entering into it muflc occafion an agitatioll or diflcurbance ir} the wateh which,, though not Senfible to the eyeX may be very effeAual in

(a) Common water, wllen cooled in. a ffate of tranquillity to feveral degrees below the freeing po-nt, will fedclenly rife up to it again if didurb¢d in ich w

manner as to occafion in it a beglnning of congelation. preventing

This content downloaded from 195.78.109.161 on Sun, 18 May 2014 16:09:56 PMAll use subject to JSTOR Terms and Conditions

preventirs*g it to lecome, in the leaX colder than the fFeesing point, without beginning to freete, in confe- quence of which its congelation mufc begs immediately after it is cooled to that point. . When I refled upon this idea, I remember a hEt which appears to me to - port it firongly. FAiIRENHEIT WAS the fid peXon who diScourered that water, when preferved in tranquillityt may be cooled fome degrees below the fFeezing poit}t without freezingX He made the diScovery while he was endfieavouring to obtain ice from water that had been purged of its air: with this intention he hasl put fome water into little glafis globes and having purged it of aIr, by boiling and the air-pump, he fuddenly Sealed up the globesX and then expofed them to the froMcy air. He wa furprizedtofindthewater remain urlfrozen much longer thall he expeAed} when at laflc he opened fome of his globes, in order ta apply a thermometer to the water, or atherwife examine vfhat Ilcate it was in The immediate conSequence -of the admiffilon of the air svas a fudden collgelati: which happened in the water; and in the icit of his globes, a firnilar prodllAion of ice vwras occa- fioned by lllaking them. - The inference that may be drawn from thefe experlments of FAHPtENlIEIT'S is fuffi- ciently obviousz, it appears to me to remove all (loubt vith regard to the above luppofition. Before thefe experiments of FAtRENHErIT occurred to my memory, I had planned a ten X fuS,-gelzced by the awbove iv1ppofition, that migllt have letl to tlle fape concluislon; but the Ihort alaration of the froN, tor one day only, dil not give me ane-to ptlt them in execlltion.

SIV. E X P E-

This content downloaded from 195.78.109.161 on Sun, 18 May 2014 16:09:56 PMAll use subject to JSTOR Terms and Conditions