In recent years, whiteness of common salt has increased with improvement of its quality. Though having shown frequently negative values in high quality salt, whiteness values expressed by ΔR andα+βhad good correlation with whiteness by perception in negative region of ΔR as in positive. Thus, whiteness in terms of ΔR seemed to be convenient for the color specification of common salt because of ease in measurement, which, however, was not expressed by absolute value. Visual white point having been below-2.9, perhaps to be about-6 as ΔR, whiteness should be expressed in terms of color difference from ΔR=-6. The zero point of ΔR was located on a straight line combining white point of chromaticity coordinate with the point of x=y=0.3132, and ΔR was defined as distance from this straight line. Negative value of ΔR in case of high quality salt was attributable to blue color, which was caused by transmission and absorbance of incident light. Judd's whiteness and one by perception had no linear relation for high quality salt, namely the former decreased in the negative region of ΔR.

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In their previous paper (This Journal 20,254-263 (1967)), the authors reported on the graphical calculations of isothermal evaporating process at 25°C of the two kinds of brines, which were supposed to be of the representative composition of ion-exchange membrane brines, by means of equilibrium diagrams of the five-components system.
In the present paper, the concentrating process of the brine belonging to Nacl-KCl-MgCl₂-CaCl₂-CaSO₄-H₂O type was studied at 25°C. Two kinds of synthetic brines containing no calcium sulfate were prepared to be evaporated to various concentrations. Samples in higher concentration region were prepared by dissolving a calculated amount of corresponding chemicals in water, instead of concentration by actual evaporation. The compositions of the solutions were analyzed chemically. and the crystals deposited were identified by means of X-ray diffraction.
Having tried to verify the validity of graphical calculation by experiment, the authors concluded as follows.
1) The compositions of solutions obtained by evaporation were found to fairly well coincide with the calculated values.
2) The process of concentration was studied by plotting the observed values on an equilibrium diagrams. As the results the kinds of crystals identified were found to completely coincide with that on the diagram. However, the composition changes of the solutions was found to coincide fairly well with the crystallization path at first, but not so well at the end of the evaporation.
3) The observed values for the equilibrium at I and J points on the equilibrium diagram were found to be not in good accord with the values given in the work of D'Ans.
4) As the solubility of CaSO₄ in the solutions decreased rapidly after the beginning of deposition of NaCl, there was scarcely any effect on the solubility of the coexisting ions.
5) It was found that the specific gravity of the solutions was found to increase linearly with the concentration of chloride ions, during the evaporation, up to the specific gravity of 1.351.

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This investigation is concerned with Loeb type acetylcellulose membrane (composition of casting solution; acetylcellulose 25weight%, acetone45%, formamide30%).
The effects of evaporation period, heating temperature and the addition of N, N-dimethylalkyl amides (substituted for formamide) on the characteristics of the membrane were examined.
The results obtained are as follows.
1) The membrane of short evaporation period and high heating temperature gives high salt rejection when the water flux is kept constant, especially in the range of high flux.
2) The greater the carbon number in N, N-dimethylalkylamide substituted for formamide is, the less the water flux of the membrane is. The salt rejection of the membrane slightly increases.
3) The more the quantity of N, N-dimethylalkylamide substituted for formamide is, the less the water flux of the membrane is. The salt rejection of the membrane slightly increases.

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