twelve o'clock
`` Yes , '' he said , `` I have seen a white , black , red , and yellow fog , '' and went off into a disquisition about optics , mediums , reflections , refractions , and all sorts of scientific terms . Well , I do n't like hard words ; when you crack them , which is plaguy tough work , you have to pick the kernel out with a cambric needle , and unless it 's soaked in wine , like the heart of a hickory nut is , it do n't taste nice , and do n't pay you for the trouble . So to change the subject , `` Doctor , '' sais I , `` how long is this everlasting mullatto lookin ' fog a goin ' to last , for it ai n't white , and it ai n't black , but kind of betwixt and between . '' Sais he , and he stopped and listened a moment , `` It will be gone by twelve o'clock to-night . '' `` What makes you think so ? '' said I. `` Do you hear that ? '' said he .