Hot water bottle

A hot water bottle is a container filled with hot water and sealed with a stopper, used to provide warmth, typically while in bed, but also for the application of heat to a specific part of the body.

Containers for warmth in bed were in use as early as the 16th century. The earliest versions contained hot coals from the dying embers of the fire, and these bed warmers were used to warm the bed before getting into it.

Containers using hot water were soon also used, with the advantage that they could remain in the bed with the sleeper.

Prior to the invention of rubber that could withstand sufficient heat, these early hot water bottles were made of a variety of materials, such as zinc, copper, glass, earthenware or wood. To prevent burning, the metal hot water flasks were wrapped in a soft cloth bag.

"India rubber" hot water bottles were in use in Britain at least by 1875. Modern conventional hot water bottles were patented in 1903 and are manufactured in natural rubber or PVC, to a design patented by the Croatian inventor Eduard Penkala. They are now commonly covered in fabric, sometimes with a novelty design.

By the late 20th century, the use of hot water bottles had markedly declined around most of the world. Not only were homes better heated, but newer items such as electric blankets were competing with hot water bottles as a source of night-time heat. However the hot water bottle remains a popular alternative in Australia,Ireland, United Kingdom, developing countries and rural areas. For example, it is widely used in Chile, where it is called a "guatero". There has been a recent surge in popularity in Japan where it is seen as an ecologically friendly and thrifty way to keep warm.

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Wikipedia