Except in very rare cases, for instance whilst the ship is en voyage, it would be, in case of fire, a sound ＿＿（41）＿＿ never to use sea water unless absolutely forced to do so. There are many circumstances in which sea water has a secondary effect. In the ＿＿（42）＿＿ spaces, for example, there would be an irreversible damage done to the steelwork and copper fitments. Sea water is very slow drying and leaves a residue which has a ＿＿（43）＿＿ action. Since metal is microscopically porous, it will be understood that mere wiping down will not completely remove the effect. In addition, acids have a definite ＿＿（44）＿＿ to any form of water. The accepted rule is: never add water to acid. The action of water in contact with the acid is to ＿＿（45）＿＿ heat. If sea water is used, there will be a production of even more choking fume.