Retort coal, that is to say, the hard graphite which is found in the retorts of gas manufactories, after the coal has been dehydrogenized, could have been obtained, but it would have been necessary to establish a special apparatus, involving great labor.
Le charbon de cornue, c'est-à-dire ce dur graphite qui se trouve dans les cornues des usines à gaz, après que la houille a été déshydrogénée, on eût pu le produire, mais il eût fallu installer des appareils spéciaux, ce qui aurait été une grosse besogne.