Improvements in or relating to the Manufacture of Caustic Alkalis or Analogous Hydrates

28,433. Stuckle, H. W. de. March 22, [date applied for under Patents Act, A.D. 1901]. Alkaline and alkaline-earth hydrates; zinc sulphide.-Alkaline hydrates are obtained by causing zinc to react on alkaline sulphides in presence of alkaline hydrates. Granular or divided zinc is dissolved in alkali in a closed metal vessel, iron filings being added if desired to facilitate the solution of hydrogen. The alkaline sulphide is then gradually added, while the vessel is suitably heated, the contents being agitated. The hydrogen assists in the formation of finely-divided zinc sulphide, which may be used as a pigment. An example is given in which sodium hydrate and sulphide are employed. Hydrates of alkaline-earth metals, such as barium, may be obtained similarly.