Cadmium Compounds - History

History

Cadmium (Latin cadmia, Greek καδμεία meaning "calamine", a cadmium-bearing mixture of minerals, which was named after the Greek mythological character, Κάδμος Cadmus, the founder of Thebes) was discovered simultaneously in 1817 by Friedrich Stromeyer and Karl Samuel Leberecht Hermann, both in Germany, as an impurity in zinc carbonate. Stromeyer found the new element as an impurity in zinc carbonate (calamine), and, for 100 years, Germany remained the only important producer of the metal. The metal was named after the Latin word for calamine, since the metal was found in this zinc compound. Stromeyer noted that some impure samples of calamine changed color when heated but pure calamine did not. He was persistent in studying these results and eventually isolated cadmium metal by roasting and reduction of the sulfide. The possibility to use cadmium yellow as pigment was recognized in the 1840s but the lack of cadmium limited this application.

Even though cadmium and its compounds may be toxic in certain forms and concentrations, the British Pharmaceutical Codex from 1907 states that cadmium iodide was used as a medication to treat "enlarged joints, scrofulous glands, and chilblains".

In 1927, the International Conference on Weights and Measures redefined the meter in terms of a red cadmium spectral line (1 m = 1,553,164.13 wavelengths). This definition has since been changed (see krypton).

After the industrial scale production of cadmium started in the 1930s and 1940s, the major application of cadmium was the coating of iron and steel to prevent corrosion; in 1944, 62% and in 1956, 59% of the cadmium in the United States was for coating. In 1956, 24% of the cadmium used within the United States was used for the second application, which was for red, orange and yellow pigments based on sulfides and selenides of cadmium. The stabilizing effect of cadmium-containing chemicals like the carboxylates cadmium laureate and cadmium stearate on PVC led to an increased use of those compounds in the 1970s and 1980s. The use of cadmium in applications such as pigments, coatings, stabilizers and alloys declined due to environmental and health regulations in the 1980s and 1990s; in 2006, only 7% of total cadmium consumption was used for plating and coating and only 10% was used for pigments. The decrease in consumption in other applications was made up by a growing demand of cadmium in nickel-cadmium batteries, which accounted for 81% of the cadmium consumption in the United States in 2006.