Paul- Emile Lecoq de Boisbaudran

French chemist known for his discoveries of the chemical elements gallium, samarium and dysprosium.

De Boisbaudran’s early work focused on supersaturation of solutions. He showed that supersaturation is destroyed by contact with crystals of an isomorphous salt, and that it is possible to prepare solutions ofanhydrous salts in a supersaturated condition (1866–1869). In 1874 he found that octahedral faces are less readily soluble than cubic faces for ammonium alum crystals. His chief work, however, was in spectroscopy and its application to rare earth elements. He analysed spectra of 35 elements, using the Bunsen burner, electric spark or both to induce luminescence and in this way discovered the lanthanidessamarium (1880), dysprosium (1886) and europium (1890). He also isolated gadolinium in 1885, the element which was previously discovered in 1880 by J.C. Galissard de Marignac.

The most notable work of de Boisbaudran was, however, discovery of gallium. In 1875 he had obtained several milligrams of gallium chloride, extracted from a sample of 52 kg of mineral ore, and found new spectroscopic lines in it. He continued the experiments using several hundred kilograms of zinc ore from the Pyrenees and in the same year isolated more than one gram of the pure metal by electrolysing a solution of its hydroxide in potassium hydroxide. Later he prepared 75 grams of gallium using more than 4 tonnes of the ore. De Boisbaudran calculated the atomic weight of gallium as 69.86, close to the currently accepted value of 69.723(1). For this work, he received the cross of the Cross of the Legion of Honour, the Davy Medal (1879) and the Prix Lacaze of 10,000 francs. He was elected a foreign member of the Royal Society in 1888. It was later claimed that Lecoq had named the element after himself, since gallus is the Latin translation of the French le coq, but Lecoq denied this in an article of 1877 and asserted that the name originates from Latin for Gaul, Gallia.