warrant. 1  authorization, sanction, or justification. 2  something that serves to give reliable or formal assurance of something; guarantee, pledge, or security. 3  something considered as having the force of a guarantee or as being positive assurance of a thing: The cavalry and artillery were considered sure warrants of success.
Potassium metal was discovered in 1807 in England by Sir Humphry Davy, who derived it from caustic potash (KOH), by the use of electrolysis of the molten salt with the newly discovered voltaic pile. Before the 18th century, no distinction was made between potassium and sodium.
Discovery of Iridium. Iridium was discovered in 1803, by English chemist Smithson Tennant in London. He found it in the residue left when crude platinum had been dissolved in aqua regia (a mixture of hydrochloric acid and nitric acid). Smithson Tennant also discovered osmium at the same time.ource: Iridium is found in natural alloys with platinum and osmium in alluvial deposits. Commercially, iridium is recovered as a by-product from the nickel mining industry. Isotopes: Iridium has 34 isotopes whose half-lives are known, with mass numbers from 165 to 198.