Examples of such additives and materials include, without limitation, various mixed valent oxides, such as magnetite, nickel oxide and the like; carbon, carbon black and graphite; sulfide semiconductors, such as FeS2 and CuFeS2; silicon carbide; various metal powders such as powders of aluminum, iron and the like; various hydrated salts and other salts, such as calcium chloride dihydrate; diatomac