i % The Caufes and Cure they happen only from the Struggle of fuch Principles, as when they have got Vent, nei- ther of themfelves, or by any Thing emit- ted with them, are of that difagreeable Na- ture, as to give any Difturbance to the Ani- mal OEconomy. CARO LV S de la Font, (a) indeed, as Well as feveral others, lays great Strefs upon Caufes of this kind, and charges Peftilentiat Dijeafcs chiefly to Mineral Exhalations of divers kinds * 5 as Arfenical, Mercurial, Sulphu- rous, &c. which he imagines the ambient Air often to be overcharged with, either from the Heat of the San, Earthquakes, or fubterraneous Fires. To all this, Perfons of different Opinion object, the In frequency of Plagues in Calabria, Naples, and feveral Parts of Sicily, where there are manifefHy very great fubterraneous Fires, fuch as occafion violent Earthquakes, and many furious and plentiful Eruptions of metallkk and mineral Fumes. A very diftin£b Relation of which 3 from his own Knowledge, may be met with from Dr. Bernard Connor, (V) who has been very curious in his Enquiries hereinto. BUT (a) DifTert. de Pefte. (h) De montis Vefuvii Inccndio.
