Dissolve yeast in one cup of water. While it softens, stir flour, sugar and salt in a large bowl. Stir in the yeast. Add remaining water. Mix until you have a soft, rather sticky dough. Cover with cloth and let rise until double in size, one to three hours. When it is high and spongy, punch it down with your fist. Divide dough into two parts and put in two 6 inch greased round casserole dishes. Cover and let rise until it reaches the top. Preheat oven to 400 degrees. Brush with butter. Bake for 40 to 60 minutes or until golden brown.