 C. L. De Ligny

C. L. De Ligny is listed with H. D. Nelson as an author of 1968 measurements of hydrocarbon solubility in water. The IUPAC-NIST record for the hexane/water system names this publication as its original experimental source and records temperature-dependent measurements. It does not identify which coauthor performed each laboratory operation.^[ref]

This work is relevant to the quantitative meaning of liquid immiscibility. A bulk system can contain separate liquid regions while its aqueous phase still contains a small, measurable amount of hydrocarbon. Equilibrium composition and the total quantity recovered from an aliquot answer different questions.

For an original calculation, suppose a homogeneous solution has hydrocarbon mole fraction $x=3\times 10^{-6}$ and total amount of substance $n=1\mathrm{mol}$. It contains $xn=3\mu \mathrm{mol}$ hydrocarbon. A representative aliquot containing $0.1\mathrm{mol}$ of the solution contains $0.3\mu \mathrm{mol}$ hydrocarbon while retaining the same mole fraction. These chosen values do not reconstruct the NIST table.

The database describes microsyringe sampling and gas chromatography with flame-ionization detection, connecting the small dissolved amount to a measurement procedure.^[ref] Sample size, composition and instrument response must be distinguished before comparing solubility measurements.