CONTRACTION OF WATER IV HEAT* 347* 



Confiding in the indications of the thermometers, from thit 

 experiment we learn, that when heat flows on all fides from the 

 ambient air into a column of ice-cold water, the warmer por- 

 tions of the fluidaflually defcend, and take pofleffion of the bot- 

 tom of the veflel. 



This downward courfe proclaims an increafed denfity, and Whence It !s 



tefiifies that the cold water is contraded by heat. As foon, the ^idet (J^l 



however, as the fluid at the bottom exhibits a temperature of per) fluid was 



38°, this courfe is retarded and foon Hopped, and with the rife " rer at the 



/, temperatures 



of temperature beyond 40 Q is totally changed; for when the near freezing; 



mafs attains this degree, the exoeriment equally mows, that the * nd the warmer 



a • i r 5 J ' • c / u •, < ( u PP er ) A uid 



warmer fluid afcends and occupies the lttmmit, by its route an- was rarer ztt ^ c 

 nouncing its diminiflied denfity, and proving that water is now higher part of* 

 expanded by heat. e cae. 



Exp. II. I filled the fame jar with water of temperature 53°; and Exp. a. Water 

 that I might obferve the phenomena of cooling, I placed it in * c 53 T as 

 the axis of a much larger cylindrical veflel, nearly full of water, cooled by enve- 

 of temperature 41°, and, by an earthen-ware fupport, railed it ,0 P'"? the veflel 

 about three inches from the bottom, taking care that the water water, it was 

 fhould be on the fame level in both veflels. As foon as I had warmer a * top 

 adjufted the two thermometers, as in the former experiment, I which it was* 

 obferved that the top of the fluid was ftill at 53°, but the bot- warmer (4?-H 

 torn had fallen to 49°. bdow - 



Top* Bottom. 



In 9 minutes, 52° - 45 



_ ]5 52 - 44 



Now, to accelerate the cooling, I withdrew by a fyphon 

 the water from the large cylinder, and fupplied its place 

 by ice-cold water, mixed with fragments of ice, which by 

 repeated cautious agitation was kept uniformly at the tempe- 

 rature of 32°. 



In 23 minutes, 48° - 42+ 



— 38 44 - 40 



_ 43 42-40 



— 46 40 - 40 



— 52 36 - 40 



— 58 35_ . * 39 



-—65 34 - 37 



— 75 u_ 34,-36 * 



* 103 34 - 34 



This 



