382 LEAD. specific gravity, its effervescing and dissolving in acidis, and becoming black in an alkaline sulphuret, neither of which characters are exhibited by heavy-spar: and it cannot be confounded with tungsten, because that mine ral does not dissolve in the mineral acids, on the contra ry, when pounded and thrown into nitric acid, it soon becomes yellovy, and it does not become black on expo sure to the action of alkaline sulphurets. 2. Next to galena or lead-glance, it is the most com mon ore of lead, but does not occur so abundantly as to be an object of importance to the metallurgist. Second Subspecies. Lead-Earth. Bleierde, Werner. This subspecies is divided into two kinds, viz. Indu cted or Solid Lead-Earth, and Friable Lead-Earth. First