Around 1820, doctors showed that which element was effective in treating goiter?

Around 1800, which scientist from Como, Italy, built a forerunner of the electric battery? Around 1807, John Colter explored the Yellowstone area after leaving which famous expedition? In 1814, which composer set Goethe's "Gretchen am Spinnrade" to music? In 1817, Giovanni Battista Caviglia led an excavation to free the Great Sphinx of Giza from what? Around 1830, Catherine McAuley founded which order of nuns to care for Dublin's poor and sick? Around 1840, chemist John William Draper took the first photograph of which heavenly body? Around 1846, Sarah Bagley became the first female operator of which communications device? Around 1850, George Boole devised a new kind of which branch of mathematics, now used in computer logic?