BORN at Hof in Bavaria, Johann Wolfgang Dobereiner began as a pharmacist's apprentice in 1794, and later practised pharmacy at Dillingburg, Karlsruhe and Strasbourg, where he set up as a manufacturer of chemicals. For a time he conducted and institute for teaching practical chemistry ; then he joined a textile company and set about improving dyeing processes. The Napoleonic wars ruined him ; but he was fortunate to come to the notice of Goethe, who obtained for him a professorship at Jena, where he remained from 1810 until he died on March 24, 1849. Döbereiner is credited with improving (and giving a correct explanation of) the making of vinegar ; but he is best known for directing attention, in 1817, to the fact that the atomic weight of strontium is the mean of those of calcium and barium. He also noticed the same relationship with other 'triads' (chlorine, bromine, iodine ; sulphur, selenium, tellurium). Dobereiner's 'triads' passed unnoticed at the time, and only after Newlands' 'law of octaves' and Mendeleef's Periodic Law had been enunciated some fifty years later did Dobereiner's work attract attention. It is also not generally known that he introduced, in 1832, the method of preparing oxygen from potassium chlorate by heating in the presence of manganese dioxide.