THE EEASON WHY. 93 



Great Is the Lord, and (greatly to be praised in the city of our God, inths 

 mountain of his holiness." PSALM XI/FIII. 



Those figures simply record the amount of caloric indicated by 

 the thermometer. The instrument will show with sufficient accu- 

 racy the relative amount of caloric in various bodies, or in the samo 

 bodies under different circumstances, but it can never determine 

 the precise amount of caloric in any one body. 



331. Why, if a hot and a cold body tvere placed near to 

 each other, would the cold one become warmer, and the hot 

 one cooler ? 



Because free caloric (that is, caloric that is not latent,) always 

 exhibits a tendency to establish an equilibrium. If twenty bodies, 

 of different temperatures, were placed in the same atmosphere, they 

 would all soon arrive at the same temperature. The caloric would 

 leave the bodies of those of the highest, and find its way to those of 

 the lowest temperature. 



332. Hew does caloric travel ? 



It travels in parallel rays in all directions with a velocity 

 approximating to that of light ; and it passes through various 

 bodies with a rapidity proportionate to their power of conduction. 



333. WTiy does melted metal run like a stream of fluid? 

 Because caloric has passed into its substance, and, repelling its 



particles, has separated them to that degree which produces 

 fluidity. 



334. Sow do we Jcnow that it is caloric passing into the 

 substance of the metal which produces this effect? 



Because, as soon as a bar of metal begins to be heated, it 

 expands and lengthens. It continues to do so, until the heat arrives 

 at that point which causes the metal to melt. 



335. Why does the iron of an ironing-box sometimes become 

 loo large for the box to receive it ? 



Because caloric has passed into the substance of the iron, and 

 repelled its particles, "by which it has become expanded. 



336. Why does the iron enter the box when it has become 

 partially cooled? 



