ABSTRACT
Melt crystallization appears to have gone through a number of successive periods or stages of development as a laboratory technique. The art of crystallization for purification or separation of chemical constituents has been practiced throughout recorded history, but most generally in form of solvent processes. With growth of organic chemistry and with an understanding of phase equilibria, potential for purification by melt crystallization increased many fold. The developments of Schildknecht on micro and ultramicro techniques make it possible to concentrate solutes from very dilute systems, by taking the most concentrated fractions to smaller and smaller tubes. Crystal quality alone, however, is not the only factor dependent upon the crystallization velocity – tube diameter combination which limits the degree of scale-up. In the simplest case of a very short cylinder cooling is provided by means of chilled metal strips which cover the faces of the flat plates connecting the rings and which can be adjusted to regulate crystal position and size.
