On the growth of NH 4Cl dendrites at very low supersaturation

Abstract

The slow development of dendritic forms from approximately spherical NH 4Cl crystals in aqueous solution has been observed at very low supersaturation. When the size of a crystal is small, only protrusions in the 〈100〉 and the 〈110〉 directions are obser ved. As the size gets larger, protrusions in the 〈111〉 directions become observable. These results confirm the hypothesis made in a previous experiment on fast dendritic growth that the tip of each dendrite was perturbed in some prescribed manner before diffusion became the rate determining factor.