27. Ash. If the sample dried as suggested be burned until all of the combustible material is consumed, there will remain a small quantity of ash or mineral matter, varying somewhat in the different kinds of cereals as shown in the chart. Upon further analysis this ash is found to consist of certain earthy substances (potash, lime, magnesia, soda, and silica) variously combined with phosphorus, sulphur, and oxygen. It is important to remember that such substances form the principal constituents of bones and teeth, and that cereals are particularly rich in the mineral matters specially required for building these hard parts of our bodies.