 Lavoisier’s list of elements was corrected and elaborated with the discovery of many new elements in the 19th century. For example, Humphrey Davy (1778–1829) isolated sodium and potassium by electrolysis, demonstrating that Lavoisier’s earths were actually compounds. In addition, caloric disappeared from the list of accepted elements with the discovery of the first law of thermodynamics in the 1840s. Thus with this changing, but growing, number of elements, chemists increasingly recognized the need for a systematization. Many attempts were made, but an early influential account was given by John Newlands (1837–98) who prepared the first periodic table showing that 62 of the 63 then known elements follow an “octave” rule according to which every eighth element has similar properties.