i7i Fluids. 277 



boiling-hot water, I began by pouring a small quantity 

 of cold water into the jar, just enough to fill up the in- 

 terstices between the ice and the glass, and to cover the 

 ice to the height of about \ of an inch ; and in pouring 

 the hot water into the jar, out of a large tea-kettle in 

 which it had been boiled, I took care to direct the stream 

 against the middle of the circular piece of paper which 

 covered the ice. 



The jar with the ice and the hot water in it being placed 

 on a table near a window, I drew away as gently as pos- 

 sible the paper which covered the surface of the ice, and 

 prepared myself to observe at my ease the result of this 

 most interesting experiment. 



A very few moments were sufficient to show me that 

 my expectation with regard to it would not be disap- 

 pointed. In the former experiment a similar cake of ice 

 had been entirely melted in less than three minutes ; but 

 in this, after more than twice that time had elapsed, the 

 ice did not show any apparent signs of even beginning to 

 melt. Its surface remained smooth and shining, and the 

 water immediately in contact with it appeared to be per- 

 fectly at rest, though the internal motions of the hot wa- 

 ter above it, which was giving off its heat to the sides of 

 the jar and to the air, were very rapid, as I could distinctly 

 perceive by means of some earthy particles or other im- 

 purities which this water happened to contain. 



I examined the ice with a very good lens, but it was a 

 long time before I could perceive any signs of its melt- 

 ing. The edges of the cake remained sharp, and the 

 minute particles of dust, which by degrees were precipi- 

 tated by the hot water as it grew colder, remained mo- 

 tionless as soon as they touched the surface of the ice. 



As the hot water had been brought from the kitchen 



