Solubilities of four heavy n-alkanes (tricosane, pentacosane, hexacosane, and octacosane) in a solvent containing seven atoms of carbon (heptane, methylcyclohexane, and toluene) are determined by simple thermal analysis. It is shown that the nature of the solvent has no major influence on the solubility and that, in a same solvent, the solubility decreases when the carbon number of the alkane chain increases. Simple expressions are applied to represent the solubility lines, which reveals that the binary mixtures are not ideal.