In a small saucepan, combine raisins and water; bring to a boil. Drain; reserve 1 cup liquid and set raisins aside.
In a bowl, cream shortening and sugar; add eggs. Add baking soda to raisin liquid. Sift together flour, nutmeg, cinnamon and salt; add alternately with raisin liquid to creamed mixture. Stir in raisins and nuts. Spread in a lightly greased 15x10x1-in. baking pan.
Bake at 350° for 25-30 minutes. If desired, glaze with confectioners' sugar icing while hot. Cut while warm.