Of WATER by HEAT. 



39« 



inches deep, and 10 inches in diameter, with a circular hole in 

 the middle of the bottom, large enough to receive the top of the 

 jar. By means of a collar and cement I fecured this bafon, fo 

 that it encircled the upper part of the jar. 



The object of the contrivance was to have the means of ap- 

 plying a cooling medium to the fuperior portion of a cylinder 

 of water, and it anfwered the purpofe completely. I introduced 

 the ball of a thermometer through the tubulature, till the extre- 

 mity of it nearly reached the axis at three-fourths of an inch 

 above the rifing of the bottom, and having fixed it in this fitua- 

 tion, I rendered the aperture water-tight, by a perforated cork 

 and lute. 



This very tall jar was placed on a table, with the interpofi- 

 tion of fome folds of thick paper, in a room without a fire, of 

 the temperature 42 °. 



I filled it with water of 50°, and poured into the bafon, 

 which embraced the top, a mixture of powdered ice and fait. 



From time to time I explored the temperature near the fur- 

 face, by inferting the bulb of a thermometer to the depth of 

 half an inch nearly in the axis. 





Bottom. 



Top. 



Air, 



One o'clock, 



5°° 



5°° 



42' 



In 1 1 minutes, 



46.+ 



— 







45 



A A — _ 



48 

 46- 





r 5 







44 — 





— ^1 — . 



42 



44 





— 41 



4i 



42 





- 51 



- 1 hour 6 min. 

 Vol. V.— P. II. 



40.+ 



40 

 39-5 



34 



34 



3E 



'At this time a thin film of 

 ice began to form in contact 

 • with the glafs. 



In 



