The article deals with measuring the densities of phenol, acetanilide, benzamide, benzoic acid, phenacetin, i-(acetylamino)-benzoic acid, i-hydroxy-benzamide, and i-acetaminophen (where i - 1, 2, 3) in 1-octanol in the wide concentration interval at T = 298.15 K. It also concerns the evaluation of apparent molar volumes and partial molar volumes at infinite dilution, <(V-2(0))over bar> as well as comparative analysis of the free volumes per molecule in the octanolic solutions, V-2(free), and in the crystal lattices, V-2(free) (cr) from the nature and position of the substitutes. Also described is the evaluation of the increments of <(V-2(0))over bar> and V-2(free) for the unsubstituted molecules and isomers and the methods to obtain partial molar volumes for various functional groups at infinite dilution in 1-octanol at T = 298.15 K. Also considered is the limiting partial molar volume of the solutes in terms of the scaled particle theory. (C) 2009 Elsevier Ltd. All rights reserved.