

THE RELATION OF SPECIFIC HEAT TO ATOMIC WEIGHT. 149 



air, as it was shown to be many years ago, when at constant pressure, by REGNAULT, 

 its atomic heat is about 27, which is a little greater than 2'48, the value deduced 

 theoretically from REGNAULT'S experiments at constant pressure. Lastly, taking 

 '173 for carbon dioxide and multiplying by 44, the value 7 '61 is obtained as the 

 molecular heat of carbon dioxide gas. If it be assumed that in the gaseous, as in the 

 solid, state the atomic heat of each element is preserved in the compound, the atomic 

 heat of gaseous carbon is left when the atomic heat of the oxygen in the dioxide is 

 deducted. We thus obtain the value 2 '65. 



This is greater than 1'8, the value chosen by KOPP, but falls between 2'89 and 

 2'42, the atomic heats of carbon, in the form of wood charcoal and natural graphite 

 respectively, deduced from the experiments of REGNAULT between and 100 C. 



This deduction from data belonging wholly to the gaseous state is of interest 

 because it is in accordance with the theoretical view that specific heat in a gas is not 

 dependent on the temperature. 



On the other hand, as the above experiments prove, atomic heats in the solid state, 

 and probably also in the liquid state, are largely dependent on the temperature, the 

 variation being abnormally great in solid carbon. It has also been shown that at the 

 same temperature the atomic heats are widely different for different elements in the 

 solid state ; but notwithstanding this fact it has been proved that the molecular heat 

 of a solid compound is approximately the sum of the atomic heats of its constituents 

 at each temperature. 



In conclusion, I desire again to express the obligations I am under to Mr. SIDNEY 

 YOUNG and to Mr. LEONAED BAIKSTOW for their assistance. 



