Heat oven to 350 degrees. Grease and flour a 10" x 15" cake pan. Cream together the sugar, butter, salt and eggs. Add the dry ingredients alternately with the orange juice; mixing well after each addition. Bake for 30 minutes, or until toothpick inserted in center comes out clean. NOTE: The cake will have a very light appearance after baking.
While cake is baking, blend together the sugar and cinnamon for the topping.
When the cake is done, remove from oven and immediately rub the 1/2 stick of butter over the top of cake until butter is completely melted. Then sprinkle the cinnamon-sugar mixture evenly on top. Cool before cutting.