ON THE NATURE OF HEAT. 1249^. 



bly to attend an increase of temperature, and contraction, 

 ought constantly to accompany its diminution. 



It is scarcely necessary to mention the contradictions to but not always, 

 this law, observed in our operations on water, iron, and 

 some saline solations, while ihey retain their fluidity; on 

 water, iron, bismuth, antimony, sulphur, the saline bodies, 

 &c. djring their transition from a solid to a fluid form; and 

 on arj^il at high temperatures. 



In the liquefaction of ice, iron, sulphur, &c., the con- 

 traction in bulk is very considerable ; yet during the ope- 

 ration, from the temperature acquired, and especially from 

 the increase of capacity, a very great quantity of caloric is 

 supposed to be absorbed. 



'2dly, The degree of expansion ought, ceteris paribus, to Expansion not 



be in direct proportion to the quantity of caloric absorbed. '" ptoportion 

 ^T - \ n , . ,. , • •• to the heat 



Now as m changes ot temperature those bodies, which supposed to be 



have the greatest capacity for caloric, absorb the greatest absorbed* 



quantity, it follows, that their expansibility ought to be 



proportionate to their capacity. This is however by no 



means the case, as will be observed by the inspection of the 



following table, in which the expansibility and th« capacity 



of several of the metals are compared. 



Capacity. Expansibility. 



Iron -98982 ..•• 10012G 



Copper -98823 ••.• 100170 



Zinc •• -64099 , 10029e 



Antimony.. •• -43292 •.•• 100109 

 Lead -39959 • • • • 100287 



Of these metals, iron and lead occupy the extremes in ** 



capacity; iron having the largest and lead the least capacity 

 for caloric ; yet lead is the most, iron the least expansible by 

 heat: that metal, therefore, which absorbs the most caloric, 

 expands the least; and, on the other hand, that which ab- 

 sorbs the least of this repulsive fluid, expands the most! 

 The same discrepancy is observed in other parts of the ta- 

 ble; antimony and lead have a capacity nearly equal, yet 

 they occupy the extremes, in the scale of expansibility. ^ 



Aware, however, that the expansibility of any body might This a^parent- 

 be regulated altogether by the degree of cohesion between ^^ °ot owing 



its " *^" ^*'°^* 



