Tropical conditions of damp heat do not, in themselves, offer a serious threat to the stability of metal objects. They do however operate to intensify corrosion when it has already begun to take place. Galvanic action becomes intensified under these conditions, particularly when salts are present in incrustations or, in general, when there is a form of moist contamination on metallic surfaces bearing stains of rancid fatty matter, residues of foodstuffs, etc. To this extent, problems of the preservation and conservation of metals in the humid tropics tend to be more acute than in temperate regions.