acid attack. acid-soluble stone materials such as the calcite in marble, limestone and travertine, as well as the internal cement that binds the resistant grains in sandstone, react with acidic solutions on contact, or on absorbing acid-forming gases in polluted air, such as oxides of sulfur or nitrogen. acid erodes the stone, leaving dull marks on polished surfaces. in time it may cause deep pitting, eventually totally obliterating the forms of statues, memorials and other sculptures. even mild household acids, including cola, wine, vinegar, lemon juice and milk, can damage vulnerable types of stone. the milder the acid, the longer it takes to etch calcite-based stone; stronger acids can cause irreparable damage in seconds.