Such margarines provide a vegan substitute for butter. Mushroom is sometimes used as a meat substitute. It is also used as a vegan substitute for gelatin. It is used in cooking as a substitute for table salt. They are sometimes ground and used as a substitute for black pepper. It is also useful as a buttermilk substitute in baking. It is most often treated as a meat substitute. They substitute meat for pollen, but still make honey from nectar. Safflower is a common substitute sometimes sold as saffron. This property makes it a popular meat substitute. Patents are pending on the use of magnesium silicate as a cement substitute. Ginger ale is a common substitute for lemonade. State secretaries can substitute ministers when absent. It had to be "chocolate substitute". Tung oil was also used during the war as a petroleum substitute.