Emily Dickinson Lexicon

PER-OX'YD, n. [per and oxyd.]

That oxyd of a given base which contains the greatest quantity of oxygen – a bad term, which ought to be entirely rejected, since different peroxyds do not always contain the same quantity of oxygen, the peroxyd of mercury being a protoxyd, the peroxyd of iron a sesquoxyd, the peroxyd of tin a deutoxyd, and the peroxyd of gold a tritoxyd.