It is said that the Potomac Refining Company has bought the Chambers farm on the Maryland side of the river, opposite the Virginia Ore Bank, and will develop the manganese that is to be found upon it. William Griffith, who is at the head of the company, recently visited the place with a number of the stockholders, and they say that the tract contains millions of dollars worth of minerals— manganese, ochre, iron ore, marble, dolomite, limestone, and so on.