copperas

plural copperases · alternative coperas · alternative copperose

1. historicaluncountableusuallyinexactAny of various metallic sulphates formed from the reaction of sulfur with iron, zinc, or copper, especially (alchemy) solutions of such compounds misunderstood as a mediator or catalyst for the transmutation of iron into copper &c.

   There is a Copperas of England, of Pisa, Germany, Cyprus, Hungary, and Italy, which only differ from each other in Colour and Perfection... The English Copperas is of a fine green; that of Cyprus and Hungary a sky-blue.

   1728, E. Chambers, Cyclopaedia, s.v. "Copperas"

   1 more example

   The ſecond way whereby bodies become blacke, is an Atramentous condition or mixture, that is a vitriolate or copperoſe quality conjoyning with a terreſtrious and aſtringent humidity, for ſo is Atramentum ſcriptorium, or writing Inke commonly made, by copperoſe caſt upon decoction or infuſion of galls... now artificiall copperoſe... is a rough and acrimonious kinde of salt drawne out of ferreous and eruginous earths, partaking chiefly of Iron and Copper, the blew of copper, the green moſt of Iron...

   1646, Thomas Browne, Pseudodoxia Epidemica, Book 6, Chapter XII: "A Digression Concerning Blacknesse", p. 336

2. archaicuncountableusuallySynonym of 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

   1 more example

   […] 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)

   Synonyms: iron(II) sulfate