Page:Life in Motion.djvu/160

140 Then we have in milk various mineral or saline substances, such as chloride of sodium or common salt, chloride of potassium (possibly), phosphates of soda and potash, phosphates of lime and magnesia, and the ash always shows traces of iron, although we are not acquainted with the exact condition in which iron exists in milk. Here is some ash of milk prepared for us by the chemists, and it would not be difficult to show you that these salts exist in it. Lastly, milk always contains water as the solvent for all the substances I have mentioned. Examine for a moment this table.

Milk, then, a typical food, contains proteid or nitrogenous matter in the form of caseinogen, carbo-hydrate in the form of milk-sugar, fat as butter, saline matters, and water. All these