1910–1911
Britannica 11th
Encyclopaedia Britannica · 11th edition
VERDIGRIS, a pigment, consisting of basic copper carbonates, made by acting upon copper plates with pyroligneous acid soaked up in cloths, exposing the plates to air, then dipping in water, and finally scraping off the greenish crust; the plate is re-exposed and the operation repeated till it is used up. Another method consists in exposing thin copper sheets to the acid vapours rising from the residues or " marcs " of wine factories, the product being scraped off, and the plate reexposed. Both processes require sev…
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- Vol. 27, pp. 1018-1018