the two marks is recorded. This operation is repeated for increasingly dilute solutions of the same polymer/solvent. A duct parallel to the capillary allows pressure equilibra- tion, so the flow of the fluid is only due to the hydrostatic head. Notice that the Cannon – Fenske viscometer [34] does not have the pressure equilibration duct, so it is not appro- priate for accurate measurements of the intrinsic viscosity.