Discovery of Calcium Element

Many calcium minerals, for instance, limestone, gypsum, alabaster, that is, mainly carbonate and sulphate minerals, have been known for a very long time. In the old days people already knew how to transform limestone into lime by calcination, as was reported by Pliny the Elder. However, it was only in 1755 that J. black showed that the weight (mass) losses during calcination were completely caused only by the removal of fixed air, i.e. carbon dioxide.
The name “alabaster” served in antiquity to denote two minerals. For one of them (a variety of calcium sulphate) the name survived up to our days, but in Egypt, for example, “alabaster” meant a variety of calcite (calcium carbonate). Gypsum has also been used from times immemorial; as a construction material. Gypsum-based solutions found application in building pyramids, temples, and other edifices. Theophrastos applied the name “gypsum” to two minerals gypsum itself and the product of its partial dehydration. Pure calcium oxide was described by the German chemists I. Pott back in 1746; however, attempts to obtain metal from it with the acid of various reducing agents failed. The right approach was suggested by H. Davy. First, he attempted to obtain calcium by passing electric current through humid earth insulated from the air by a kerosene layer. (In a similar way he had tried to prepare barium and strontium.) As a result of his experiments, Davy developed the following method of preparing pure alkaline-earth metals. He mixed humid earth with 1/3 (by mass) of mercury oxide and placed the mixture into a platinum vessel connected to the positive pole of a high-voltage battery. Then he introduced a drop of mercury at the centre of the mixture. The platinum electrode placed in the drop was connected with the negative pole of the battery. Amalgam obtained in this way was then separated into mercury and silvery-white metal, calcium. Davy prepared pure calcium in 1808. In the same year J. Berzelius and M. Pontin obtained calcium independently of Davy using a similar method. The name of the element originates from the Latin word calx, which means “lime”. ..

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