Mix sugar and cocoa. Add water, butter, raisins, spices and salt. Boil 4 minutes. Cool to room temperature.
Sift together flour, baking powder and soda. Add to raisin mixture and mix until well blended. Stir in walnuts. Pour into greased 13 X 9 X 2" pan. Bake in moderate oven (350°) 35 minutes or until done. Remove from oven and cool on rack.