l6iJ On the Contraction of JiTiter hij Hetif. 



gels the start of the bottom soon by 4°, and attains the 

 lowest tcn)peraturc of 34" very long before the other fall? 

 -to the same degree. 



These circumstances, I think, lead to the conclusion, 

 thai bv the loss of caloric, water at 53° is contracted and 

 rendered .-ipeclfically heavier, and that this continues to 

 •happen till the water come to the temperature of 40°, at 

 which period an opposite effect is produced ; for now the 

 water, as it cools, becomes specifically lighter, or is ex- 

 panded. 



In this, as well as the former experiment, the complete 

 chano;e in the situation, whicli the warmer and colder parts 

 •of the fluid affected, in the progress botli of the heating 

 and cooling, while every external circumstance of the pro- 

 cess continued unaltered, is particularly worthy of remark. 



Experiment III. 



I took a glass jar, 1 7" 8 inches deep, and 4*5 in diameter, 

 internal measure, having a neck and tubalature very near 

 the bottom, f provided also a cylindrical bason of tinned 

 iron, 4-8 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 ce- 

 ment I secured this bason, so that it encircled the upper 

 part of the jar. 



The object of the contrivance was to have the means of 

 applying a cooling medium to the superior portion of a 

 cylinder of water, and it answered the purpose completely. 

 I introduced the ball of a thermometer through the tubula- 

 ture, till the extremitv of it nearly reached the axis at 

 three-fourths of an inch above the rising of the bottom, 

 and having fixed it in this situation, I rendered the aperture 

 water-tight, by a perforated cork and lute. 



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

 position of some folds of thick paper, in a room without 

 a fire, of the temperature 42°. 



I filled it with water of 50", and ponred into the bason, 

 w'hich embraced the top, a mixture of powdered ice antl 

 salt. 



From tim.e to time I explored the temperature near the 

 surface, by inserting the bulb of a thermometer to the, 

 depth of hal .' an inch nearly in the axis, 



Botfom. Top. Air. 



One o'clock 56° 50*^' 42° 



In 1 1 minutes 46* + — ■ 

 _ 15 ___, — 45 48 



In 



