Heat oven to 350 degrees. Grease and dust with flour two 8 inch pans. Beat egg whites. Gradually beat in 1/2 cup of sugar. Continue beating until very stiff and glossy. Sift remaining sugar, flour, baking soda, and salt in another bowl. Pour in oil, and half of buttermilk. Beat one minute on medium speed. Add remaining buttermilk, egg yolks and chocolate. Beat one minute more. Fold meringue into batter gently. Bak 30-35 minutes.