Periodic Elements
Gallium
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A metal that melts at 29.76 degrees C, which is below body temperature, so a piece held in the hand turns to liquid. Mendeleev predicted it in 1871 as eka-aluminium; Paul-Emile Lecoq de Boisbaudran found it by spectroscopy in 1875 in sphalerite from the Pyrenees, and the agreement between prediction and measurement was the first great vindication of the periodic table. He named it for Gallia, Latin for France; the suggestion that he had hidden his own name in it, le coq being gallus in Latin, he denied in print in 1877. Gallium arsenide and gallium nitride underlie LEDs and fast electronics.
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Open Questions
Origin of the NameNamed for Gallia, the Latin name for France, which is the reason Lecoq de Boisbaudran gave in announcing the discovery. That gallus is Latin for a rooster, and that his own surname Lecoq is French for the rooster, was noticed at once and has been repeated ever since, but whether he intended the second reading cannot be established from the announcement. 2 Sourced to the subject's own accountRecorded as unknown rather than debated. The question is about a private intention, and the naming announcement offers the patriotic reason alone. A statement in Lecoq de Boisbaudran's own correspondence or working papers would settle it, and failing that it may simply not be answerable. Identity
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Overview
Gallium was discovered in 1875 by the French chemist Paul-Emile Lecoq de Boisbaudran, who first detected it by its spectral lines and then isolated the metal. Its name honours Gallia, the Latin name for France, though some suspected a hidden pun, since Lecoq means the cock and the Latin for cock is gallus. Gallium is a soft, silvery metal with the curious property of melting just above room temperature, so that it will liquefy in a warm hand. Liquid over most of the range of everyday temperatures, gallium has little structural use, but its compounds, above all gallium arsenide and gallium nitride, are vital semiconductors in light-emitting diodes, laser diodes, solar cells and high-frequency electronics.
Gallium's low melting point has made it a favourite of popular science demonstrations and novelty gifts: spoons cast from the metal appear solid at room temperature but dissolve into a puddle when used to stir a hot drink, a trick sturdy enough to have entertained chemistry classrooms for generations. In a more practical vein, gallium is a key component of Galinstan, a liquid alloy of gallium, indium and tin developed as a non-toxic replacement for mercury in thermometers and other instruments after mercury's health and environmental risks led many countries to restrict it.
The Fulfilment of Eka-Aluminium
Gallium is one of the three great vindications of the periodic table. In 1871 Dmitri Mendeleev had predicted an undiscovered element below aluminium, which he called eka-aluminium, and specified its density, melting point and chemistry. When Lecoq de Boisbaudran characterised gallium, Mendeleev wrote to point out that the density the Frenchman first reported was wrong and that his own predicted value should be trusted; on repurifying his sample, Lecoq de Boisbaudran found Mendeleev right. The episode, in which a theorist corrected a discoverer about a substance he had never seen, became one of the most celebrated demonstrations that the periodic system could genuinely predict nature. Some historians doubt the coq pun was intended at all, since Lecoq de Boisbaudran himself denied choosing the name as a play on his own; whatever the truth, the coincidence has been retold ever since.
The three confirmations of Mendeleev's predictions, scandium in 1879, gallium in 1875 and germanium in 1886, all arrived within seventeen years of his original 1869 table, a remarkably fast vindication for a scheme that many senior chemists had initially dismissed as speculative or premature. Mendeleev's own priority over the German chemist Lothar Meyer, who had devised a similar periodic arrangement at almost the same time but published his predictions less boldly, is itself one of the enduring footnotes of the table's history.
Cross-Tradition Connections
Named For
Gallium is named for Gallia, the Latin name for France. A pun has long been alleged, on gallus, Latin for cock, and the discoverer's name Lecoq de Boisbaudran. He denied it. The Latin place name is the only derivation he gave.
Sources
Open Questions (1 open question)
Did Lecoq de Boisbaudran name gallium after himself as well as after France?
The discoverer gave the patriotic reason, that he had named the element for Gallia, the Latin name for France. The coincidence that gallus is Latin for a rooster, and that his own surname, Lecoq, is French for the rooster, was pointed out at once and has been repeated ever since. Whether the second reading was intended, quietly enjoyed, or only ever imagined by other people cannot be settled from the naming announcement, which offers the patriotic reason alone.
What would resolve this A statement of intent in Lecoq de Boisbaudran's own correspondence or working papers. Failing that, the question concerns a private intention and may simply not be answerable.
History of chemistry, and French archival work on the Lecoq de Boisbaudran papers.Royal Society of Chemistry, Periodic Table: Gallium
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