Further cooling of the filtrate, sometimes called the mother liquor, in an ice-water or ice salt bath may allow isolation of a second crop of crystals. The filtrate can also be concentrated by evaporating part of the solvent and cooling the residual solution. The crystals isolated as a second or even a third crop are likely to be less pure than those in the first. Consequently, the various crops should not be combined until their purity has been assessed by comparison of their melting points.