The mother-liquor of the crystallisers is pumped back into the evaporating pans for further concentration.
Cooley's Cyclopdia of Practical Receipts and Collateral Information in the Arts, Manufactures, Professions, and Trades..., Sixth Edition, Volume I|Arnold Cooley
The salt so separating may be either anhydrous or a "hydrate" of greater concentration than the mother-liquor.
Scientific American Supplement, No. 508, September 26, 1885|Various