n. [ Pref. bi- + sulphate. ] (Chem.) A sulphate in which but half the hydrogen of the acid is replaced by a positive element or radical, thus making the proportion of the acid to the positive or basic portion twice what it is in the normal sulphates; an acid sulphate. [ 1913 Webster ]
n. [ NL. sulphas, sulphatis, fr. L. sulphur, sulfur, brimstone, sulphur: cf. F. sulfate. ] (Chem.) A salt of sulphuric acid. [ 1913 Webster ]