The bubble column chromatograph consists of a vertical cylinder sealed at the lower end and partially filled with liquid. Gas is introduced at the bottom in such a way that long, bullet shaped bubbles rise slowly through the liquid. Previous work has shown that the column diameter can be chosen such that the liquid film flowing past the bubble approaches equilibrium with the contents of the bubble. This is the essential requirement of a chromatographic system. This work is a study of the effect of the bubbles on the longitudinal dispersion in the liquid phase. It was found that dispersion increased with increasing bubble length and film thickness for a constant number of bubbles. Thus, it is desirable to use short bubbles when using the bubble column as a chromatographic device.