Copperas
Full definition of copperas
Noun
copperas
(uncountable)- iron(II) sulfate.
- 1843, Thomas_Carlyle, , book 2, ch. 6, Monk Samson… 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;