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The process developed in the U K to produce magnesium hydroxide from seawater is described, together with the heat treatment that the hydroxide receives to produce the active oxide. Some of the characteristics required of the dolomite used in the process are also discussed. Impurities introduced by the seawater are noted and the means by which they can be reduced explained.

Montmorillonite and illite clays were examined for their ability to take up cesium and strontium radioisotopes from solution. Uptakes onto near homoionic Na, Ca, Mg and Sr clays were assessed by distribution coefficients measured at different Na, Cs, Mg, Ca and Sr solution concentrations. Some experiments were carried out at different pH, and to check the effect of differing anions. In addition measurements of the uptake of ruthenium species were made.

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The conductivity of analcite has been measured as a function of temperature and water content. The self-diffusion of sodium ions in analcite ma20 . A1203 .4siO2.2H20) has been studied using 22Na, and the results are shown to be in agreement with the conductivity data for analcite containing more than 25 % of water (2 mole of water per formula = 100 %). Values of AH*, AS* and AG* at 400" K are quoted. The data are interpreted in terms of a rate-controlling process involving the energy barrier for migration of a water molecule.The migration of monovalent cations in anhydrous analcite (M20 . Al2O3. 4Si02) has been studied by Beattie 1 using a conductance technique. The conductivity of zeolites as a function of their water content has been examined by Rabinowitsch and Wood.2 Their experiments indicated that the conductivity of chabazite (CaO . A1203 . 4 SiO;? . 6 H20) increased with increasing water content. This suggests that under certain conditions zeolitic water may be partially ionized, which is unlikely. Similar results were obtained using ammonia as the sorbed gas.The water molecule has an effective radius of approximately 1.3r8, so that it can readily migrate through zeolites such as analcite. Tiselius3 studied the diffusion of water into analcite by an optical method and concluded that the diffusion coefficient was concentration dependent. Beattie 4 has recently shown that conduction in analcite containing two cations is governed by the slowermoving ion, except at low concentrations of this ion. If the energy barrier for the migration of a water molecule were greater than that for sodium ion migration it might be expected that in a hydrous analcite the former would represent the rate-controlling process. In this way measurement of the conductivity of hydrated analcite would give a temperature dependence related to the energy barrier for the diffusion of the uncharged water molecule. The work to be described relates the migration of sodium ions in analcite to the water content.