Corrosion of metallic articles packed in wooden cases is unlikely to occur during normal conditions of storage or transport unless the moisture content of the wood, and hence the relative humidity of the air inside the case, is unduly high. If goods are stored for long periods or under adverse conditions there is an additional risk of corrosion due to acidic vapours given off by the wood. An account is given of recent investigations on the production of acetic acid when certain timbers are stored under warm, damp conditions and its effect in causing corrosion of metals.