Rub the butter into the flour with the salt and sugar. Put the baking soda in the curds and pour it into the flour, knead to a soft dough adding more curds or water if necessary. Divide it into 2 balls, flatten them to 2 inch thickness, place them on a in-greased tin and bake (350 degrees) till a golden crust is formed on top. Split them while hot and spread butter and jam.