Effect of Bodies on Light and Heat. 403 



pared with hydrogen as one, and in the third column is given the pro- 

 duct of the first two. It is called the atomic heat. The practical iden- 

 tity of the quantities in the last column proves that the specific heat is 

 the same for all atoms, regardless of their name or weight. Or, in other 

 words, it alwa}^s takes the same amount of heat to raise an atom of any 

 body one degree in temperature, and this, notwithstanding the fact that 



the atoms of some bodies are many times heavier than those of others. 

 To make this a little more clear, suppose the amount used of each ele- 

 ment named in the table is 10,000 Ibs. , and that the ngures in the col- 

 umn of atomic weights are pounds, and the ngures in the column of 

 specific heats represent so many heat units. Take Antimony, for ex- 

 ample. Its atom weighs 122 Ibs. Ten thousand pounds divided by 

 122 gives 82 as the number of atoms in that weight of the metal. This 

 divided into 523, the units of specific heat, gives 6.4, nearly, as the 

 atomic heat. Again, the atom of Lithium weighs but 7 pounds ; so 

 there are 1,429 of them in 10,000 Ibs., which, divided into the 9,408 

 heat units, gives nearly 6. 6 units to each atom. The wonderful fact 

 shown in this table will be referred to again. 



