THE KELATION OF SPECIFIC HEAT TO ATOMIC WEIGHT. 



147 



B- 



Remembering what a large factor, 429 '9, is used in calculating these figures, it will 

 be seen that the differences are really small, being about 1 5 per cent, of the molecular 

 heat at the lowest temperature and falling to about 3 per cent, at 300 abs. It will 

 be noticed that in this case B is throughout larger than A. 



The results of these experiments show that NEUMANN'S law may be regarded as 

 approximately valid for the -specific heats at all temperatures. They also confirm the 

 view that the specific heat of a solid is not a measure of the work done in separating 

 the molecules of the substance, but that its amount is determined almost entirely by 

 the nature of the atoms composing the physical molecules. 



All the facts at our disposal show that there is not a great difference between the 

 specific heats of elements in the solid and liquid states, but that in every case the 

 latter is the greater, as shown in the following examples : 



TABLE VI. Specific Heats. 



The atomic heat in the liquid state is thus in all cases greater than in the solid, 

 and in the above cases ranges from 5 '6 to 8 '5. In the gaseous state at constant 

 volume the atomic heat is, however, much smaller, being approximately for hydrogen 

 2 '42, for oxygen 2 '48, and for iodine, a solid at common temperatures and in some 

 characters approaching the metals, 3 '3. In respect to specific heat, therefore, the 

 liquid state is not intermediate between the solid and the gaseous states. This may 

 possibly be explained by the assumption that in the solid and in the gas at constant 

 volume every molecule in the mass remains in the same condition relatively to every 

 other molecule, for in the solid all are rigidly bound together by " cohesion," and in 



u 2 



