I have been unable to deduce meaning of "charcoal" in the end of this paragraph:
"'It's easy enough to understand it,' replied the choleric old
gentleman. 'If you had been a younger man, you would have
been in the secret long ago; and besides,' added Wardle, after a
moment's hesitation, 'the truth is, that, knowing nothing of this
matter, I have rather pressed Emily for four or five months past,
to receive favourably (if she could; I would never attempt to
force a girl's inclinations) the addresses of a young gentleman
down in our neighbourhood. I have no doubt that, girl-like, to
enhance her own value and increase the ardour of Mr. Snodgrass,
she has represented this matter in very glowing colours, and that
they have both arrived at the conclusion that they are a terribly-
persecuted pair of unfortunates, and have no resource but
clandestine matrimony, or charcoal. Now the question is, what's to be done?'"