Law of corresponding states

The law of corresponding states is an empirical law encapsulates the finding that the equations of state for many real gases are remarkably similar when they are expressed in terms of reduced temperatures ($T_{r}=T/T_{c}$), pressures, ($p_{r}=p/p_{c}$) and volumes ($V_{r}=V/V_{c}$).

References

1. Johannes Diderik van der Waals "The law of corresponding states for different substances", Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen 15 II pp. 971-981 (1913)