1. Residual brines, containing chiefly calcium and magnesium chlorides, obtained after the salt has been crystallized and removed from solution. The term "mother liquor" is widely used when salt is produced by use of vacuum pan and gainer operations. In the solar salt evaporation process, the term "bitterns" is often used in place of the term "mother liquor".
2.A solution substantially freed from undissolved matter by a solid/liquid separation process, such as filtration or decanting.