from
The Collaborative International Dictionary of English v.0.48
Microcrith \Mi`cro*crith"\, n. [Micro- + crith.] (Chem.)
The weight of the half hydrogen molecule, or of the hydrogen
atom, at one time taken as the standard in comparing the
atomic weights of the elements; thus, an atom of oxygen
weighs sixteen microcriths. This unit is no longer used, and
has been replaced by the {Dalton}, which is of approximately
the same value. See {molecular weight} and {Crith}. --J. P.
Cooke.
[1913 Webster +PJC]