Note 44 — Chapter III · OSMOTIC PRESSURE AND THE THEORY OF SOLUTION II

One may imagine, first, n molecules of the solute as a gas, with the pressure Pgas, in 1 c.c. Then, one may imagine, crudely, the n molecules of solute, in a free (gas) space of (1 − v) c.c., in the center of 1 c.c. of the solvent, and exerting by their impacts a pressure Posm., against the solvent. According to Boyle's law, we should then have, Pgas × 1 = Posm. × (1 − v), and therefore Posm. = Pgas / (1 − v).