Some of the electrolytic conditions for the bittern with sodium hydroxide addition were studied, i. e. anode current density (DA) which may cause corrosion and heating of PbO₂anode, and cathode current density (DK) which may deterinine the available chlorine in magnesium bleaching powder, and temperature of electrolysis which may govern the rate of magnesium bleaching powder formation and CIO^-ion concentration.
The optimum DAof PbO₂anode was found to be less than 0.2A/cm², with which DA, no corrosion and heating of the PbO₂anode was observed. The effect of DK on the available chlorine content was remarkable, and crystalline and easily filterable magnesium bleaching powder of good quality, with about 44% available chlorine, was obtained at DKof less than 0.2A/cm².
The optimum temperature of electrolysis was found to be about 30°C. A larger scale apparatus of 20A input was constructed and comparable good results were obtained.

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In their previous paper (This Journal, 14, 227-34,(1960)), the authors computed graphically the isothermal evaporation of the natural gas brine at 25°C by means of equilibrium diagram of the five-components system: NaCl-KCl-MgCl₂-CaCl₂-H₂O. Since the natural gas brine contains much more NaCl compared with the other salts in the solution, the NaCl crystallizes out first, and comes out continuously over the whole course of evaporation. Therefore, the equilibrium diagram may be simplified by assuming the system to be always saturated with NaCl, as in the case of oceanic salts treated by van't Hoff.
In the present paper, two kinds of such simplified diagrams were drawn, one on the triangular cordinate and the other on the stereogeometric axis, and the change of liquid phase compositions were computed graphically. To draw the diagram on the tetrahedron cordinate, as previously reported, 23 points were necessary, while the present simplified diagrams need only 11 points, which are less than half of the former ones. The drawn diagrams were of course, less complicated, and the graphical computations much easier. By comparing the resultant values for 5 points computed by means of 3 different diagrams, namely one on the triangular cordinate, one on the stereogeometric axis and one on the tetrahedron cordinate, the authors found out fairly good coincidence among them. Especially, the values gained with triangular cordinate were found to coincide almost completely with the ones gained with the normal tetrahedron cordinate.
From these reults, the authors concluded that the diagram on the triangular cordinate was best suited for such calculation.

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[in Japanese]

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A small quantity of boric acid is often absorbed into magnesium hydroxide crystals precipitated by the reaction between bittern and milky lime. Concerning this phenomenon, some studies have already been reported on production of magnesium hydroxide through absorption of boric acid to its crystals (Bulletin of the Society of Salt Science, Japan 14, 234, 275 (1960)).
The present authors studied on some of the effects of the boric acid as mineralizer to the thermal properties of magnesia clinker produced by firing such magnesium hydroxide.
The results were summarized as follows: boric acid easily dissolved into the crystal lattice of periclase at high temperature, as easily as silicon oxide and ferric oxide a solid solution contained boric acid was quickly formed among periclase particles at a temperature lower than the usual firing temperature of clinker, and its constructure was more stable than that of solutions of other components. By X-ray analysis, the mineralogical composition of bond part was found to be mainly Mg₃(BO₃)₂. If the absorbed amount of boric acid was increased by more than 1.0 per cent as B₂O₃, the themal properties of the clinker would deteriorate remarkably with the increasing volume of bond part.
Sea water magnesia generally contains a little of lime, silica, alumina, ferric oxide etc., as impurities. The absorbed boric acid was found to form several complex double salts with these components which in turn that phase promoted crystallization of periclase.

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From the study of former data, a general relationship was found to exist between the vapour pressure depression and ionic concentration of saturated solutions of single inorganic salt.
A theory, similar to the Dalton's partial pressure law, was established on the v. p. d. of a sat. soln. consisting of inorganic salts, follwing experimental proof of a hypothesis derived from the above-mentioned information, using a newly devised humidity measuring apparatus. The theory is that.
ΔP=ΣΔP'n
where ΔP'n=C'n·ΔNn
and ΔNn=ΔPn/Cn
Contrary to the case of diluted soln., the solute in a sat. soln. has its own v. p. d. characteristics shown as the specific molecular depression, by which the influence of impurities on the humidity of inorganic salt crystals could be determined quantitatively. The v. p. d. characteristics of a salt in a sat. soln. can be explained from the view point of hydration.
n: foot note n indicates the kind of salt
ΔP: total v. p. d. of a sat. soln. consisting of two or more salts
ΔP'n: partial v. p. d. of a salt in a sat. soln, consisting of two ormore salts
ΔPn: v. p. d. of a sat. soln. of a single salt
Cn: concentration of a sat. soln, of a single salt
C'n: c. of a particular salt in a sat. soln. consisting of two or more salts
ΔNn: specific molecular depression of v. p. in a sat. soln.

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