The object is a well-used traditional copper saucepan. Copper pans have been used for centuries, but nowadays are most associated with large kitchens in Victorian mansions. Excellent examples can be seen at National Trust properties, such as Petworth House.
The use of copper in cooking has a number of advantages. Firstly copper is an excellent conductor of heat, which means that a pan will heat up quickly and evenly. It also cools quickly, which gives great control when cooking delicate items and sauces. Copper is also durable and small dents can even add to the character of the pan. Copper is hygienic, as it has anti-bacterial qualities.
One problem that could occur with a pan made entirely of copper is the fact that it reacts to acid, such as that contained in vinegar and some fruits. Copper oxides can leach into the ingredients, which can make food taste strange and over time can lead to mild poisoning. To avoid this health risk, traditional copper pans were lined with tin, which is inert, and after years of use and cleaning, pans could be sent away to be re-tinned.
Copper pans are still produced and modern versions often have linings of stainless steel, which is attractive, but less conductive than tin and more likely to have food stick. Copper pans are expensive and the majority of pans sold today are made of steel, cast iron or aluminium, often with non-stick coatings.