The osmotic pressure of 3He-4He solutions is shown to follow in a natural way from the separation of the specific heat in a quasiparticle contribution and a 4He-contribution. Expressions for important thermodynamic properties such as the chemical potentials, the internal energy, the entropy, specific heat, osmotic pressure, etc. are given for the case the quasiparticle gas can be treated as a nearly-ideal Fermi gas. The zero kelvin and the high-temperature limits are tabulated. A first-order approximation is given for the effect of the 3He quasiparticle contribution to the second-sound velocity in the high-temperature limit.