The
pressure of a gas, however, can be used to construct a perfect-gas temperature scale
that is independent of the identity of the gas. The perfect-gas scale turns out to be
identical to the thermodynamic temperature scale to be introduced in Section 3.2d,
so we shall use the latter term from now on to avoid a proliferation of names. On the
thermodynamic temperature scale, temperatures are denoted T and are normally
reported in kelvins (K; not °K). Thermodynamic and Celsius temperatures are related
by the exact expression