276 Inquiries concerning the Mode of the 



instance, a quarter of an inch thick, and if the hot cube 

 be placed upon this plate immediately above the cold 

 cube, the heat will descend through the metallic plate with 

 a certain degree of facility, and will heat the cold cube. 



If a dry board of the same thickness with the metallic 

 plate be substituted in its place, the heat will descend 

 through the wood, but with much less celerity than 

 through the plate of silver. 



But if a stratum of water or of any other liquid be sub- 

 stituted in place of the metallic plate or of the board, 

 the result will be very different. If, for instance, the cold 

 cube being placed in a large tub resting on the middle 

 of its bottom, the hot cube be suspended over it by 

 cords, or in any other manner so that the lower surface 

 of the hot cube be immediately above the upper surface 

 of the cold cube, at the distance of a quarter of an inch, 

 and the tub be then filled with water at the same tem- 

 perature as that of the cold cube, the heat will not 

 descend from the hot cube to the cold one through the 



o 



stratum of water of a quarter of an inch in thickness that 

 separates them. 



We may with propriety call silver a g ood conductor of 

 heat, and dry wood a bad conductor ; but what shall we 

 say of water ? I have called it a non-conductor for want 

 of a more suitable term, but I always felt that that word 

 expresses but imperfectly the quality that was meant to 

 be designated. 



In the experiment of the two cubes plunged in water, 

 if the hot cube be placed below and the cold cube above 

 it, the heat will not only be communicated from the hot 

 to the cold cube, but it will pass even more rapidly than 

 when the two cubes are separated by a plate of silver. 

 But in this case it is evident that the heat is transported 



