Hydrogen chloride is used in the manufacture of phosphoric acid, chlorine dioxide, ammonium chloride, fertilizers, dyes, and artificial silk and pigments in paint. Hydrogen chloride is also used in the hydro chlorination of rubber, to separate cotton from wool. It is used in the production of tin and tantalum, and as a metal treating agent. A main industrial use of hydrochloric acid is the cleaning, or pickling of metals. The production of glucose and corn sugar from starch and the refining of cane sugar also is a use of hydrochloric acid. Hydrochloric acid is very important in the manufacture of synthetic rubber and plastics, and is used in making glue and gelatin. As hydrochloric acid, it is also used to manufacture iron and steel, clean metals, and make solvents, bleaches, and chloride salts. Hydrochloric acid is used to neutralize the waste streams, soap refining, leather tanning, textiles and brewing. It is also used to prevent bacteria in toilet bowls, and in food processing as a starch modifier. Hydrochloric acid is very important in the digestion of foods. It is present in the walls of the stomach where the acid helps in the digestion of foods.