copperas
nounEtymology From Middle English coperas, coperose (“metallic sulfate”), from Old French coperose. Compare French couperose (“sulfate”), Medieval Latin cuprosa, Late Latin aqua cuprosa, Latin cupri rosa, "rose of copper".
1
Usually Iron(II) sulfate.
- It were superfluous to describe the Process of making the Aqua fortis; it shall suffice to let you know, that our common Coperas makes this Aquafortis well enough for our purpose[…]1707, J[ohn] Mortimer, The Whole Art of Husbandry; or, The Way of Managing and Improving of Land. […], London: […] J[ohn] H[umphreys] for H[enry] Mortlock […], and J[onathan] Robinson […], →OCLC:
- […] what a change has introduced itself everywhere into human affairs! How human affairs shall now circulate everywhere not healthy life-blood in them, but, as it were, a detestable copperas banker’s ink;1843 April, Thomas Carlyle, “ch. 6, Monk Samson”, in Past and Present, American edition, Boston, Mass.: Charles C[offin] Little and James Brown, published 1843, →OCLC, book II (The Ancient Monk):
2
Usually An obsolete sulphate compound with one of the three metals, zinc, copper or iron.
- Derived terms
- blue copperas, green copperas, white copperas, yellow copperas