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The chemical elements were discovered in identified minerals and with the help of the ... first refinements ... (1807), potassium (1807), calcium (1808 ...
Calcium is a chemical element; it has symbol Ca and atomic number 20. ... Calcium is the first (lightest) element to have six naturally occurring isotopes. [14]
Sodium was first isolated by Davy in the same year by passing an electric current through molten sodium hydroxide (NaOH). When Davy heard that Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, he tried it himself. Davy was successful, and discovered calcium in 1808 by electrolyzing a mixture of lime and mercuric oxide.
The two discovered a new element in a molybdenum sample that was used in a cyclotron, the first element to be discovered by synthesis. It had been predicted by Mendeleev in 1871 as eka-manganese. [171] [172] [173] In 1952, Paul W. Merrill found its spectral lines in S-type red giants. [174]
In 1641, the first patent in North America was issued to Samuel Winslow by the General Court of Massachusetts for a new method of making salt. [ 3 ] [ 4 ] [ 5 ] On April 10, 1790, President George Washington signed the Patent Act of 1790 (1 Stat. 109) into law which proclaimed that patents were to be authorized for "any useful art, manufacture ...
The first reactor took 11 months to build, and the majority of the 51,000-person workforce did not know what they were working on. Workers arriving at the Hanford Site in August 1945. AP Photo
A map may prove that Marco Polo discovered America more than two centuries before Christopher Columbus. A sheepskin map, believed to be a copy of the 13th century Italian explorer's, may indicate ...
700 BC: Pell's equations are first studied by Baudhayana in India, the first diophantine equations known to be studied. [19] 700 BC: Grammar is first studied in India (note that Sanskrit Vyākaraṇa predates Pāṇini). [20] 600 BC: Thales of Miletus is credited with proving Thales's theorem. [21] [22] [23]