Two liquids which do not react chemically are placed in a bent tube as shown in figure. The heights of the liquids above their surface of separation are

The pressure at the interface must be same, calculated via either tube. Since, both tubes are open to the atmosphere, we must have

${\mathrm{h}}_1{\mathrm{\rho }}_1\mathrm{g}={\mathrm{h}}_2{\mathrm{\rho }}_2\mathrm{g}\Rightarrow {\mathrm{h}}_1{\mathrm{\rho }}_1={\mathrm{h}}_2{\mathrm{\rho }}_2$

$\Rightarrow \mathrm{h\rho }=\text{ constant ⇒}\mathrm{h}\propto \frac{1}{\mathrm{\rho }}$