Coal Gas 2 : A flammable and highly toxic gaseous mixture produced by the destructive distillation of bituminous coal in highly heated fire-glass or silica retorts or in by-product coke ovens
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}