where A is a constant for a particular viscometer, which may be evaluated using liquids of known viscosity; t is time, and ρ is the density of the liquid. The above equation is valid if the whole pressure difference applied across the capillary is used in overcoming viscous forces. However, the potential energy of the liquid column imparts kinetic energy to the fluid. In order to correct the contribution of the kinetic energy, as the length of the capillary increases, the radius decreases [31, 32]. Several methods exist for characterization of the solution viscosity or, more specifically, the capacity of the solute to increase the viscosity of the solution. That capacity is quantified by using one of several different measures of solution viscosity.