Iron(II) sulfate was used in the textile industry for centuries as a dye fixative. It is used historically to blacken leather and as a constituent of ink. The preparation of sulfuric acid ('oil of vitriol') by the distillation of green vitriol (Iron(II) sulfate) has been known for at least 700 years. Together with other iron compounds, ferrous sulfate is used to fortify foods and to treat and prevent iron deficiency anemia. Constipation is a frequent and uncomfortable side effect associated with the administration of oral iron supplements. Stool softeners often are prescribed to prevent constipation. Ferrous sulfate was used in the manufacture
Nationalization of oil supplies the control of the oil within their country. Furthermore, technological innovation and managerial expertise increased dramatically after World War II, which increased the bargaining power of producing countries. Increased bargaining power allowed the companies to change their mode of operation. Stephen J. Kobrin states that “During the interwar period and through the 1950s, international petroleum was a very tight oligopoly dominated by seven major international oil companies (Exxon, Shell, BP, Gulf, Texaco, Mobil and Chevron—as they are known today). However, between 1953 and 1972 more than three hundred private firms and fifty state-owned firms entered the industry, drawn by the