CONTRACTION OF WATER BY HEAT. 341 



ibe mark fo foon, that I thought the mark had flipt down* 



which I prefently raifed to the water, and as foon as ever I 



mixed the fait with the fnow, the water rofe very fad, about 



one-half inch above it. I took up then the glafs, and found 



the water all fluid ftill : it was again fet down in the fait and 



fnow ; but when I came about an hour after to view it, the 



ball was broke, and the water turned to hard ice, both in the * 



ball and irera'V 



From this experiment Dr. Croune drew the conclufion, that Whence he in- 

 water, when fubjected to cold, a&ually began to expand before ^xlliioh^% 

 it began to freeze. On announcing it, however, to the Royal But Dr. Hooke 

 Society, on the 6th of February 1683, Dr. Hooke immediate, y4Sto d tneVe£ 

 exprefled flrong doubts, and afcribed the afcent of, the water .f e l. 

 in the neck of the veflel to the fhrinking of the glafs occafioned 

 by the cold. 



To obviate this objection, and to preclude, as far as was pof- Dr. C. repeated 

 {ible, the influence of the change of capacity in the a PP aratus -^" P V![veiit 

 from an alteration of its temperature, a bolt-head was immerfed in a veflel pre- 

 in a mixture of fait and fnow, and into it, when cooled, was, V10ufl y cooled; 

 poured, to a certain height, water previoufly brought to 

 near the freezing point. The water began inftarttjy to rife as 

 before, and when it had afcended about one-fourth of,an. inch 

 in the ftem, the veflel was taken out, the whole water remaining 

 fluid. 



Thefe experiments, fupported by others of a limilar. nature, which gave fa- ; 

 communicated by Dr. Slare to the Society on the 20th v 'ft" f tf*W*1 

 the fame month, appear to have fatisfied its members, in ge- 

 neral, of this fact, that water, when on the point of congealing, 

 and while flill fluid, is actually fomewhat dilated previous 

 to the remarkable expanfion which accompanies its converiipn 

 into ice. 



Dr. Hooke, however, continued unthaken, and retained the but not to Dr. 

 doubts he had exprefled. ■ ■ Hooke ' 



Remarkable as the fact, as now ftated, mull have appeared, 

 it feems not to have excited particular attention, nor to have fo- 

 licited more minute examination; and indeed though phi, 

 lofophers did not lofe fight of it, yet for near a century no 

 one inveftigated it 1 more carefully. Mairan, in his treatife 

 on ice in 1719, and Du Creft in lws difleriation on thermo, 



Birch's Hijiory of the Royal Society, Vol iv,p. 263. 



meters 



