Temperature the Common Property of Systems in Thermal Equilibrium

3 Temperature The Common Property of Systems in Thermal Equilibrium 

Consider a large bath - large enough that its hotness is not effected by the transfer to, or from it, of a small amount of energy - in which we place a cylinder-and-piston arrangement containing one mole of nitrogen. After thermal equilibrium is reached, we record the pressure (Pj) and volume (Vj) of the gas inside the cylinder. 

We now move the piston so that the volume changes to and record the corresponding pressure when thermal equilibrium is reached. We 

We repeat next the experiment replacing nitrogen with helium, and 

All these states of N2 and He, therefore, share a common property which we call temperature. Notice that this property is not some abstract quantity rather, it has the effect of determining in this case the value of pressure, once the value of the volume is specified. 

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