Minerals, Electrolytes and Fluid
This chapter considers the substances that appear in food analyses as ash. These are the substances that are left behind when the carbon, hydrogen and nitrogen have all been burnt away in the presence of oxygen as, for example, in a bomb calorimeter. Commonly called minerals, these substances occur in nature in water, in the soil and in rocks and are taken up by the roots of plants and thereby nd their way into animals. Humans, therefore, consume minerals both from plant and animal sources, although foods of animal origin generally have a higher content as the minerals have been concentrated in the tissues.