The Mystery of Black Soul

MENDOZA, Argentina -- You just know it when you're drinking great wine.

At twilight, our group was crowded around a table in the dining room of a tin-roofed "cottage" built in 1912, tasting the wines of Alma Negra. We had ridden the bus way out into the country to find the house, which had originally stood in splendid isolation, though in the century si…