# Dispersion in Chromatography Columns - The Golay Equation > Page 74

In addition it
is seen, from equation (56), that the expression for u_{opt} is very similar to that for a packed column
but the expression for H_{min.}
is much simpler as it is devoid of the (A) term from the multipath effect.

Due to the relative simple, and precisely defined, geometry of the capillary column it contains no arbitrary constants involved with the packing quality of the column such as (g) and (l). As a consequence, the properties of the capillary column can be explored further in a relatively straightforward manner. In the following treatment an LC capillary column will be considered despite, at this time, equipment for the efficient use of LC capillary columns is not available. From Poiseuille's Equation, describing the flow of liquid through an open tube, operating at the optimum velocity,

_{} (59)

Where, (l) is the length of the column,

(P) is the pressure drop across the column,

and (h) is the viscosity of the flowing liquid.