Danger From Copper Saucepans. The precise danger from the use of copper saucepans, or stewpans, imperfectly tinned, is far from rightly understood. It appears that the acid contained in stews and other made dishes, as lemon-juice, though it does not dissolve copper by being merely boiled in it a few minutes, nevertheless, if allowed to cool and stand in it for some time, will acquire poisonous matter, as verdigris, in the form of a green band, or crust, inside the vessel. It has likewise been proved that weak solutions of common salt, such as are daily made by adding a little salt to boiling vegetables, fish, or meat, act powerfully on copper vessels, although strong solutions or brine would not affect them. It is, however, in vain to hope that cooks will attend to the nice distinctions by which copper stewpans may be rendered safe; the general advice given by prudent physicians is, therefore, against their use at all.
The kettles in which the soups are made should be well tinned, and kept particularly clean, by being washed in hot water and rubbed dry before they are put away. If they are not kept well tinned, the taste as well as the colour of the soup will be liable to be affected by the iron; and if the soup-kettle be made of copper, and the tinning not quite perfect, everything cooked in it will be more or less poisonous, as everything which is sweet, salt, or sour, extracts verdigris from copper.