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33° Method for afore mentioned three genera. The fpecific gravity of thefe fparry fubftances, is above 4.000. The other fedtion of folid fubftances belonging to this genus, have a lamellar tex ture ; their fpecific gravity is likewife above 4.000, or at leaft near to it. They are not adted upon by any acid ; when fufed with bo rax, they immediately difcover a phofphores- cent light. They are not foluble in 500 times the quantity of water. They neutralife potafh when fufed, or ftrongly ignited with it in a crucible, and form thereby fulphate of potafh, leaving an earth behind, which is foluble in nitric and muriatic ' acid, and which pofifefTes the properties men tioned in the foregoing fedtion. The fubftances thtis afcertained to contain baryt earth, muft likewife contain a prevalent portion of that earth, to belong properly to this genus.—The different fpecies may be dis- tinguifhed according to the texture, fhape, and mixture.——There is another lubftance lately found, whofe principal bafis proves to conftitute a new genus of earth, which has fome refemblance to the baryt earth, it is called STRON-