As it looks that the freezing method may have lower energy requirements and less equipment scaling and corrosion compared with distillation, a small vacuum freezing condensing equipment driven by a 5 HP compressor is constructed based on five years' experiments on the heat pump for the purpose of getting data on heat balance, efficiency and others necessary for the application of the process of vacuum freezing condensation. The freezer uses a revolving drum in which methyl chloride is evaporated through a direct expansion system. The demineralizator uses a series of separators for vibration, vacuum filtration, and continuous centrifugal separation. The total energy of condensing 1 liter of water from saline water is 50 watts-hour. However, through the freezing-system only 15 watts-hour is enough in this apparatus. In 100 HP epuipments on this method it is expected to reduce the energy to 12 watts-hour.

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Sea water was previously treated with NaOH and Na₂CO₃ for removing Mg⁺⁺ and Ca⁺⁺, and then the treated sea water was evaporated to various degrees of concentration. Boiling points of these solutions were measured under 1.1 atm. Specific gravity, viscosity and surface tension of these solutions were also measured at various temperatures, from 20° to 96°C. The values at the boiling points were determined by extrapolation of these data. Obtained values were compared with the values of the ordinary brine at the same Cl^- concentration. The specific gravity of the treated sea water was larger than that of ordinary brine, the viscosity lower and the boiling point almost the same.

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The 7 double salts crystallized from th sexinary system “Na-K-Mg-Ca-Cl-SO₄-H₂O”, namely glauberite, krugite (its existence doubtful), pentacalciumsulfate, polyhalite, syngenite, 2 Na₂SO₄·CaSO₄·2 H₂O and Na₂SO₄·5 CaSO₄·3 H₂O, are studied by the same manner as the previous paper. The A.S.T.M. data file lists 4 of these, i.e., glauberite, pentacalciumsulfate, polyhalite and syngenite. The conclusions of this paper are as follows:(1) On glauberite,(a) the larg estd spacing was not 6.22Å (A.S.T.M.) but 7.56Å.(b) the strongest line of d=3.13Å(A.S.T.M.) was separated into 2 peaks, d=3.16Å and d=3.11Å, consequently,(c) the strongest line proceeded to d=3.93Å, therefore,(d) the intensity ratios were corrected for all lines.(2) On krugite, in spite of tests by J. H. van't Hoff's or A. Geiger's synthetic method, it was unable to synthetized artificially. The deposited salts were confirmed as anhydrite by both chemical analysis and powder X-ray diffraction.(3) On pentacalciumsulfate and polyhalite, there was some difference between observed d value and the A.S.T.M. value.(4) On syngenite, the A.S.T.M. data was considered to be entirely mistaken.(5) On the other 2 residual double salts, d spacings and intensity retios of all diffracted lines were determined.

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In the previous paper, we reported that the salt of good quality was produced by concentrating the brine in addition of small quantities of Mn-salt and the surface active agents such as solvitan-ester of fatty acid. In this report, we explained that the addition of small quantities of the polyhydric-alcohols such as Sobitol, Mannitol, or Glycerol, with Mn-salts and the surface activeagents was effective for preventing the occlusion of Iron-compound.

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The substance having mean mole-ratio; MgO:SiO₂:H₂O=2:3:n, was made by a new proposed process of decomposing magnesium basic silicate with the acid solution, and its adsorbing capacity was compared with that of ordinal one prepared by the reaction between MgCl₂ and Na₂SiO₃ solution.
(1) The substance obtained by the new process absorbs methylen-blue more efficiently than ordinal one, following Langmuir's formula in the range of dilute concentration.
(2) According to the X-ray analysis, such is amorphous but begins to crystalize when being dried, and it proved magnesium silicates including free SiO₂.
(3) The above substance adsorbs methylen-bule very much, nevertheless it contains SiO₂ less adsorbing than ordinal magnesium trisilicate, which is scarcely understandable. But with the electron micros cope and by the B.E.T. method of measuring surface area, it was found that the surface have a porous appearance, as is the state formed in the new process.

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Generally Mg(OH)₂ precipitated by the reaction between magnesium salt and alkali hydroxide solution, has the hexagonal layer lattice of brucite type. On the otherhand, it is said that there is a labile state having the large energy. In this study the labile Mg(OH)₂ was made from NH₄OH and MgCl₂ solution, and the property was investigated with the automatic recording X-ray diffractometer. The labile substance in water is a coagel, giveng the extremely diffused band at 28° (2θ) of diffraction pattern. And it becomes a xerogel-like substance when being dried, but shows the pattern indicating diffused bands of weak intensity at 9°, 18.5°-23°, 35°-38° and 59°, which contain some reflection of stable Mg(OH)₂; 18.5°, 38° and 59°. The above gel or gel-like substance is unstable and rapidly changes into the stable Mg(OH)₂ of brucite type, which gives the comparatively strong reflection at 38° or 18.5°.

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