noun
retort carbon; gas carbon
Technical term for a hard, dense form of carbon deposited on the walls of coal-gas retorts; used in electrodes, arc lamps, and batteries.
レトルトカーボンは、かつてアーク灯の電極に使われていた。
Retort carbon was once used for arc lamp electrodes.
Variant with interpunct; less common in running text.
Loanword from English 'retort carbon'.