Structures of the cupola type in which an electric current is used or produced for heating purposes.
(1) Note. For electrical or wave energy apparatus, excepting radiant energy apparatus provided for in Class 250, Radiant Energy, specialized for the preparation of gaseous compounds or elements and involving chemical reactions which are caused by more than the mere thermal effects of the electrical or wave energy, see Class 204, Chemistry: Electrical and Wave Energy, appropriate subclasses, and other related classes.
