A re-compilation of data was conducted on an oceanic quinary system at 0°, 10°, 25°, 55°, 83° and 110° to discuss mother liquid in the process of manufacturing salt and liquid attached to the surface of crystals. Factors of the system treated as a matrix (by Dr. Harada) were calculated from the above data and were shown in the attached tables. The method of applying the factors to the system was also shown by an example. An ideal process of concentrating sea water at 0°, 25°, 55° and 83° was calculated from the above-mentioned data, and the results thus obtained were shown in the attached tables.
The authors studied calcium salts, crystallized during the concentration of the brine treated with caustic soda for removal of magnesium and calcium ions, and found them to be double salts of sodium and calcium sulfates in contrast with single calcium sulfates crystallized during concentration of the brine from, solar field. A week long experiment was made to study crystallization of calcium double salts in the 2nd and 3rd pans of the triple-effect vacuum evaporator (temperatures of the liquid were 85°for the 2nd and 50° for the 3rd, respectively) in the refined salt manufacturing factory. Then, a transition point of the double salt was examined in the laboratory, and the following results were obtained; 1. Chemical composition of the mother liquid in both the 2nd and 3rd pans became constant in about 20 hours after the beginning. 2. In the 2nd pan, calcium sulfate hemihydrate crystallized first for 1 or 2 hours, and then a glauberite (Na2SO4·CaSO4) began to crystallize. 3. In the 3rd pan, gypsum crystallized first for 9 hours and then a double salt (2 Na2SO4·CaSO4·2H2O) began to crystallize. The crystal was so fine that suspended in mother liquid. 4. In the lst pan, a glauberite crystallized as in the 2nd pan. 5. In the laboratory experiment, at 70°Na2SO4·CaSO4·2H2O was crystallized first and then glauberite began to crystallize. Stable double salts crystallized at 80° and 60° were glauberite and 2Na2SO4·CaSO4·2H2O, respectively. The transition point of the double salt was near 70°.