Foot-warmers

From Festipedia, hosted by the FR Heritage Group

Foot-warmers are metal tanks, about the size of a pillow, that warm the feet of passengers in cold weather.

They are naphthalene-filled, naphthalene having the characteristic that it melts at a comfortable temperature for feet. When cold, the naphthalene solidifies, while when heated it melts. The solidification of the warmer from the melted to solid state releases a lot of heat energy at a constant temperature.

The foot-warmer tank has a handle at one end, as it would be a little too hot to carry around otherwise.

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