Copper Acetate, Cu(C₂H₃O₂)₂,H₂O

Copper Acetate, Cu(C₂H₃O₂)₂,H₂O, has long been known by the name verdigris (The coatings of basic carbonate which are formed on copper in the air are also sometimes called verdigris.). It is obtained by alternately covering copper plates with residues from the preparation of wine and exposing to oxidation by the atmospheric oxygen. By means of the latter, acetic acid is formed from the alcohol of the residues, and the copper is converted into the acetate. This is deposited as the basic salt on the copper plates in bluish-green masses, and is placed in this form on the market for use as a pigment. The normal salt is obtained by crystallisation from dilute acetic acid, and forms dark green crystals, which are also employed for painting and dyeing.