Hypertext Webster Gateway: "protosulphide"
From Webster's Revised Unabridged Dictionary (1913) (web1913)
Protosulphide \Pro`to*sul"phide\, n. [Proto- + sulphide.]
(Chem.)
That one of a series of sulphides of any element which has
the lowest proportion of sulphur; a sulphide with but one
atom of sulphur in the molecule.
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