ABSTRACT
The organic constituents of the foreign matter in raw water are of vegetable and animal origin and are taken up by the water in flowing over the ground or by direct contamination with sewage and industrial refuse. Feedwater containing organic matter may cause foaming, because the suspended particles collect on the surface of the water in the boiler and impede the liberation of the steam bubbles arising to the surface. The inorganic impurities in suspension or in colloidal solution consist of clay, silica, iron, alumina, and the like. The more common soluble inorganic impurities are calcium, magnesium, potassium, and sodium in
the form of carbonates, sulfates, chlorides, and nitrates. Raw water also contains a certain quantity of gases in solution, such as air, C02, and occasionally, hydrogen sulfide.
