FOIL

Europe was covered with a dense fog during nearly two months. On the 2'2d of May, 1822, about 5 o'clock m the afternoon, a fog covered Paris and the neighbourhood, which liad the odour of nitrous gas: it continued about an hour. Dry fogs, or those in wnich no moisture is present, are supposed to be the vapours and ashes ejected by volcanos, and diffused in the atmosphere by the winds. [s. 473]