$7\mathrm{.}2$ In the pendant drop technique for measuring the oil$-$water interfacial tension $($IFT$),$ the drop remains attached to the pendant drop tube $($syringe or needle$),$ at which point it is dimensioned. However, the drop eventually breaks away when the suspended weight of the drop $($due to gravity force$)$ is no longer supported by the IFT force. For one such experiment, the following data were obtained: inside diameter of the pendant drop tube $=0\mathrm{.}10in.$; drop diameter at the point of breaking away $=0\mathrm{.}22in.$; ${}_w=1\mathrm{.}05\frac{g}{c}{m}^3$; and ${}_o=0\mathrm{.}85\frac{g}{c}{m}^3.$ Calculate the oil$-$water IFT.

Note:

Misak $(1968)$ correlation for the value of $(H)$ is:

For $0\mathrm{.}400$