In the previous paper it was made clear that potassium chloride crystallizes as single crystals of octahedral shape in the case of crystallization from potassium chloride solution which contains a small amount of the mixture of MnSO₄and (NaPO₃)n as addition. agent. In this paper the growth of the above octahedral crystal was studied by microscopic observation. Results obtained are as follows.
(1) When the supersaturation ratio of the above solution are from 1.04 to 1.06, concentric patterns appear on the surface of the growing crystal. When the ratio is under 1.03, irregular steps and hill rocks are observed. When the ratio is above 1.06, needle-like crystals deposit on the growing surface.
(2) Such a concentric pattern is considered to depend on the spiral growth because the center of the pattern resembles a spiral. But in many cases, hill rocks are found in the center.
(3) Applying Cabrera's theory, the value of the specific surface free energy calculated from data of the supersaturation, step spacing and step height of the pattern, seems too large compared with the value accepted generally.

抄録全体を表示

The distributions of copper, zinc, lead, iron, aluminum, manganese and molybdenum in the deposits and the mother liquor due to concentration of sea water were studied. Concentrations were carried out under the following conditions:-
Concentration degrees:
3/10 (a range of deposition of carbonates and hydroxides), 1/10 (a range of deposition of gypsum) and 1/60 (a range of deposition of sodium chloride) of the volume of original sea water.
Temperature: 40&C and boiling temperature.
pH of sea water: 5.0, 7.9 and 10.0.
Analysis of each element was made on the deposits and the final mother liquor and the following results were obtained:-
1. There are no serious differences in the distribution of these metals by temperatures, but there are fair differerences by pH of sea water.
2. The behaviors of copper and zinc resemble each other, and the greater part of these metals are concentrated in the mother liquor.
3. The lead is distributed partly in the carbonate or hydroxide deposits, and more in the sodium chloride crystals.
4. The behaviors of aluminum and iron resemble each other, and the greater part of these metals are distributed in the early stage deposits.
5. A part of manganese is distributed in the sodium chloride deposit, but there is no definite tendency as to the remainder.
6. The molybdenum is not distributed in the deposits, and is almost all concentrated in the mother liquor regardless to the temperature or pH of sea water.

抄録全体を表示

In a process which magnesium dissolved in sea water is removed completely as hydroxide by direct electrolysis, the amount of magnesium and pH value of catholyte change significantly in relation to the quantity of electrolytic current, when the amount, of magnesium dissolved in catholyte becomes quite small.
In this report, the relationship between the amount of magnesium and pH value corresponding to the quantity of electrolytic current was determined in detail under the above mentioned conditions.
Also the behaviour of calcium in sea water was studied.
The relationship between the amount of magnesium and pH value in catholyte was the same as that obtained by the addition of sodium hydroxide in sea water, and the amounts of magnesium dissolved in catholyte agreed with the solubility data of magnesium hydroxide in sodium chloride solutions having various pH values.

抄録全体を表示

In separating NS salt B from various bitterns at 100°C and 50°C, calculations and studies on the yield of potassium, quantity of magnesium hydroxide to be added, quantity of water to be evaporated etc. were done using the phase diagrams of the quinary system KCl-K₂SO₄-MgCl₂-MgSO₄-Mg(OH) ₂-H₂O. The yield of potassium as NS salt B from bittern was calculated to be about 50 per cent at 100°C and about 80 per cent at 50°C.
Phase diagram indicating the interrelation between the kind of deposited triple salt and the sodium content of original bittern was also completed.
Tests for the separation of NS salt B with 1 ton open pan were made at Onahama Salt Plant of the Japan Monopoly Corporation, and by the results of these tests, it was found to be possible to separate potassium in bittern directly in the form of sulfate. Furthermore, it was confirmed that boron dissolved in bittern was partly codeposited in NS salt B, which was found to contain about 0.6-0.7mg-B per gram solid of triple salt.

抄録全体を表示

Reduction in mechanical strength of iron and steel can result from the absorption of atomic hydrogen produced by the action of acid on the metal.
This is designated as hydrogen embrittlement. When acidcleaning large iron and steel equipment, it is necessary to prevent hydrogen embrittlement which may result serious failures.
The author investigated the effect of Urotropin on hydrogen embrittlement by measuring the mechanical strengths of mild steel, cast iron and steel casting which have been acid-cleaned and illustrated that Urotropin has the effect of preventing hydorogen embrittlement.

抄録全体を表示

The author investigated effects of 5% and 10% hydrochloric acid and sulphuric acid solutions, in which 0.1% and 0.2% Urotropin was contained, on the removal of oxide films from cast iron, and illustrated that 10% hydrochloric acid solution conthining 0.2% Urotropin was the most effective. When employing this solution, oxide films were removed perfectly in relatively short time and the metal surface left behind was very smooth.
Then, acid cleaning of turbine parts was performed using the same solution. It was concluded that acid cleaning was more effective than mechanical cleaning.

抄録全体を表示

Vapour pressures of sea water and brine were obtained using dry and wet-bulb temperatures of hygrometer. The method is based on the fact, the principle that the wet-bulb thermometer of a hygrometer stands at an equilibrated temperature because of the vapour pressures on the wet-bulb and surrounding air, should hold true when the wet-bulb is wetted by sea water and brine.
An empirical formula was obtained on ratios of vapour pressures of sea water and brine, under normal temperatures and different densities against those of fresh water at saturation.
Accordingly, it was found possible to calculate the vapour pressures of sea water and brine from fresh water vapour pressures.

抄録全体を表示

Vol. 13 (1959) No. 6 p. 289-290

抄録全体を表示