HEAT OR CALORIC. 



125 



It is worthy of observation that all the gases, excepting hydrogen, 

 have, according to Petit and Dulong, less specific heat than water ; 

 this is the fact even with steam. It would seem that they had some 

 doubts as to the correctness of this result. 



Apparatus for illustrating capacities for heat. Dr. Hare. 



" Let the vessels 

 A,B,and C, be sup- 

 plied with water 

 thro ugh the tube T. 

 which commmuni- 

 cates with each of 

 them, by a hori- 

 zontal channel in 

 the wooden block. 

 The water will rise 

 to the same level in all.' Of course the resistance made by the wa- 

 ter, in each vessel, to the entrance of more of this liquid will be the 

 same, and will be measured by the height of the column of water in 

 the tube T. Hence if the height of this column were made the in- 

 dex of the quantity received by each vessel, it would lead to the im- 

 pression that they had all received the same quantity. But it must 

 be obvious, that the quantities severally received, will be as different 

 as are their horizontal areas. Of course we must 'not assume the 

 resistance exerted by the water within the vessels against a further 

 accession of water from the tube, as any evidence of an equality in the 

 portions previously received by them." 



