Sentence:  Mum would heat the water in a <WSD>copper</WSD> in the kitchen and transfer it to the tin bath. 
Meaning of the word marked with <WSD> tags:  A large pot, often used for heating water or washing clothes over a fire. In Australasia at least, it could also be a fixed installation made of copper, with a fire underneath and its own chimney. Generally made redundant by the advent of the washing machine.