Effect of solution layer thickness on crystallization

Abstract

In the "Annaks of Geology and Mineralogy of Russia", in the article on “Crystallization in a solid medium,” I already described the experience of converting polyhydrate magnesium sulfate hydrate, directly formed during the evaporation of the solution, into heptahydrate. At the same time, I noted that the rapidly growing needles and fibers of heptahydrate hydrate with apparently they spread at the same speed both in a free solution and penetrate the crystals of a polyhydrate hydrate (namely MgS0₄ 12 aq). It must be assumed that such an extreme slowdown in the progress of the phenomenon in extra-thin layers occurs under the influence of partial capillary forces of extension between the walls of the wedge space and its contents.