The brine which is now being produced by ion exchange membrane methoh belongs to the sysem of NaCl-KCl-MgCl₂-CaCl₂-H₂O (CaSO₄is neglected here for its minute content). The production of salt from the brine produced by ion exchange membrane method has been put into practice for these several years. Nevertheless, no equilibrium diagrams of this system have been reported other than the one presented by J. D'Ans (at 25°) some forty years ago. As for the system, however, the authors considered it sufficient to examine only the part which was indispensable for salt and bittern making industries, and conducted a study to examine the crystallizing areas of KCl, carnallite and other salts in the necessary part of the system at the equilibrium temperatures of 110° 90° 70° 45° and 25° The results of the study were as follows:
1. Crystallizing area of KCl
Three kinds of sample solution with the MgCl₂: CaCl₂ratio of 5:1, 3:1 and 1:1 were prepared and saturated with KCl and NaCl. At lower temperatures, the more (MgCl₂+CaCl₂)% increased, the more linearly KCl % decreased. At the same temperature, the more the content of (MgCl₂+CaCl₂) increased, the larger the difference of KCl% between the (1:1) solution and (5:1) and (3:1) solutions became. This trend was especially true at higher temperatures. However, on the diagram of a regular triangle shape, the corners of which represented Na₂Cl₂, K₂Cl₂and (MgCl₂+ CaCl₂), these three kinds of solution were arranged by the same curves, respectively, at the same temperature.
2. Crystallizing area of Carnallite
The both boundary lines of KCl area and carnallite area were nearly parallel with the MgCl₂side on the diagram of regular triangle, the corners of which were K₂Cl₂side on the diagram of regular triangle, the corners of which were K₂Cl₂, MgCl₂and CaCl₂. At higher temperatures, these boundary lines were more distant from the MgCl₂side.
3. Crystallizing area of bischofite and tachyhydrite
The crystallizing area of these two salts exists between the MgCl₂side and the boundary line between carnallite and the above two double salts. The trend of the crystallizing area toward the temperature was the same as in the case of KCl.
In this study, the authors estimated from the equilibrium values of the system excluding NaCl and the analytical values of the coexisted residues, the boundary lines between bischo-fite and tachydrite at the above-mentioned temperatures because they were unknown except for the one at 25°.

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The authors reported in their previous paper (This Journal, 24, 189-196 (1971)) the polythermic equilibrium diagrams of the five component system: Na, K, Mg Cl, SO₄-H₂O at the temperature ranging from 50° to 110°.
This paper reports the resuits of the study which the authors made on the equilibriums of the quinary reciprocal system. To obtain the basic data for a phase-rule analysis on the concentrating process of ion-exchange-membrane brine, the mixture of ion-exchange-membrane brine and salf-field brine, etc., the authors interpolated the compositions of liquid phases and the kinds of solid phases stable at 83stable at 83° and 110°C from the above-mentioned polytherms, and made up two new tables for these quinary systems.
These values were protted on the triangular cordinate (Jaeneck projection) and stereogeometric axis (D'Ans, projection), and the diagrams thus obtained were studied. As the result, the authors reached the following conclusion:
1. At 83°C, NaCl, loeweite (Na₂SO₄·MgSO₄·5/2H₂O) and langbeinite (K₂SO₄·2MgSO₄) can coexist stably in the divariant system on the line connecting the monovariant points V and W.
2. On the diagram at 110°C, the area of langbeinite field was found to be about twice and that of loeweite about seven times larger than those in the diagrams of D'Ans.
3. At 83°C and 110°C, the most part of Na₂SO₄field on the diagrams of D'Ans was found to be occupied by d'ansite (MgSO₄·3NaCl·9Na₂SO₄).

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It is well known that ferric hydroxides, which is widely used as inorganic ion adsorbent, have a high adsorption capacity, and that they adsorb almost all inorganic ions on suitable conditions.
The present investigation was carried out to establish optimal conditions to prepare granular hydrated ferric oxide of high adsorption capacity, which can be used as an ion-exchanger in the form of membranes or in columns.
The results are summarized as follows;
1) The amorphous hydrated ferric oxide shows an amphoteric adsorption and has a rather high stability.
It has especially a high adsorption capacity for chloride ion.α-and βA-FeO(OH) adsorbs only chloride ion.
Their adsorption capacities are less than that of amorphous one.
2) The adsorption capacity of the amorphous hydrated ferric oxide and α-FeO(OH) are influenced by the pH of mother liquor, in which they are precipitated; that is, the adsorption capacity of α-FeO(OH) for chloride ion and the same capacity of amorphous hydrated oxide for potassium ion decreased as the pH of the mother liquor increased.
The amorphous hydrated oxide prepared in mother liquor of pH 7 indicated the highest adsorption capacity for chloride ion.
The adsorption capacity of the product decreased as the pH of the mother liquor deviates from this optimum value.
The adsorption of βA-FeO(OH) was higher, when it was prepared at the lower hydrolysis temperature.
3) It can be generally stated that the shorter the period of aging, the better the adsorption capacity. The adsorption of α-FeO(OH), however, reaches a limiting value after the aging period of five days and the adsorption of βA-FeO(OH) reaches after one day respectively, but none of them change any more.
4) It is found that there is a correlation among the adsorption capacity, crystallinity and pH of mother liquor or hydrolysis temperature; that is, the adsorption capacity decreases as the crystallinity increases, while the crystallinity increases as the pH of mother liquor in the case of α-FeO(OH) or hydrolysis temperature for βA-FeO(OH) increases.

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The distribution of effective temperature differences in the flash evaporator was investigated by examining the data on the operation of the flash evaporator, and this study proved to be useful for analying this process. Also, it was found that the elevation of the boiling point in the process of desalting sea-water by flash evaporation method could be expressed by the following formula:
dt=C^1.173(0.1120±180×10^-3t)
50<t<100°C 5<C<11wt%
Non-equilibrium temperature differences were calculated by the following formula:
Δt=1.056Re^-0.469Pr^-0.667t^-1.636
It was pointed out that the overall heat transfer coefficient of 4,500 (Kcal/m²hr°C) could be attained easily.

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