Combining expressions for the Gibbs–Duhem equation in each phase and assuming systematic equilibrium (i.e. that the temperature and pressure is constant throughout the system), we recover the Gibbs' phase rule.
把每一个相态的吉布斯-杜安方程的表达式合并，并假设系统平衡（也就是说，温度和压强在系统中始终是恒定的），我们便可以得出吉布斯相律。