In a bowl, combine tapioca, 2/3 cup sugar, 1/8 teaspoon salt, cherries and the 1 cup cherry juice (if there isn't enough cherry juice to make 1 cup, add a little water). Mix and put into a lightly buttered 1 1/2-quart baking dish. Dot top of cherry mixture with 2 teaspoons butter, cut in small pieces.
Bake at 425° for 12 minutes.
In a mixing bowl, combine biscuit mix, 2 tablespoons sugar, and evaporated milk. Remove cherry mixture from the oven and drop dough by tablespoonfuls on top to make 4 dumplings. Bake for about 12 minutes longer, or until dumplings are lightly browned. Cherry Cobbler serves 4. Serve warm with vanilla ice cream of a dollop of whipped topping.