We made a study regarding four different decomposing methods in order to produce potassium carbonate or sulfate.
1. When Engel's salt is agitated in hot water, it is decomposed into basic magnesium and carbonate solution as indicated in the following formula:
4 (KHCO₃·MgCO₃·4H₂O)→2K₂CO₃+3MgCO₃·Mg(OH)₂·3H₂O+CO₂+14H₂O
By concentrating this solution, crystalized potassium carbonate can be obtained. In this case, the yield of potassium amounts to approximately 95%.
2. When Engel's salt is agitated withMagnesium hydroxide in cold water, it is decomposed into magnesium carbonate and potassium carbonate solution.
2(KHCO₃·MgCO₃·4H₂O)+Mg(OH)₂→K₂CO₃+MgCO₃·3H₂O+H₂O
By this method, it requires much time to complete reaction, and in order to increase the purity of crystalized potassium carbonate, the quantity of magnesium hydroxide to be added must be equivalent to that of Engel's salt. In this case, the yield of potassium is 75%.
3. When Engel's salt is calcined, it is decomposed into magnesia and potassium carbonate.
2 (KHCO₃·MgCO₃·4H₂O)→2MgO+K₂CO₃+3CO₂+9H₂O
The solubility of this potassium carbonate against coldwater is so high that when the calcination is extracted by cold water, potassium carbonate can easilybe separated from magnesia. In this case, the yield of potassium amounts to 92%.
4. When the mixture of Engel's salt and magnesium sulfate is agitated in hot water, potassium sulfate solution and basic magnesium carbonatecan be obtained asindicated in the following formula:
8(KHCO₃·MgCO₃·4H₂O)+4MgSO₄→3 (3MgCO₃·Mg(OH)₂·3H₂O)+4K₂SO₄+4CO₂
When this solution is concentrated, crystalized potassium sulfate can be obtained. The yield of potassium in this case amounts to 92%-94%, and magnesium sulfate to be added to Engel's salt must be equivalent Engel's salt in quantity.

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When Engel's salt is heated at the temperature higher than 550°C for 30 minutes, the potassium contained in this double salt completely changes into potassium carbonate, When it is extracted by water, it can be separated from the residue as potassium carbonate solution. In addition, when this solution is concentrated, crystalized potassium carbonate can be obtained. Thls crystal contains 1.5mol of water, but scarecely contains magnesium and other impurities. The yield of potassium thus obtained amounts to 93%. The residue obtained by removing potassium carbonate solution seldom contains potassium. It is not pure magnesium oxide, but it is considered basic magnesium carbonate or a mixture of baslc magnesium carbonate and magnesium oxide.

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It was reported in the previous literatures that molybdenum, vanadium and uranium contained in sea water are concentrated in bittern. Therefore, we conducted the present study for the purpose of gathering these constituents from bittern by adsorption of ferric hydroxide. This paper gives data on adsorption curves obtained by experiments which were conducted to find the relationship between pH and adsorption ratio. Optimum pH of adsorption was 3 to 4 in molybdenum, 3 to 7 in vanadium and above 6 in uranium respectively, but only adsorption pH of uranium changed in case of co-existence with carbonate ion, and it adsorbed with pH 7 to 8 in this case.
In addition, this paper gives data on desorption curves for water extraction from adsorbent obtained by experiments which were conducted to find the relationship between pH and desorption ratio. pH of desorption was above 4 in molybdenum, above 7 in vanadium and below 6 in uranium repectively, as pH becomes the higher, desorption of molybdenum and vanadium becomes more complete. Desorption of uranium was done above pH 9 in case of Co-existence with carbonate ion, These results showed a possibility of seprating molybdenum, vanadium and uranium from each other by application of adsorption and desorption. It was also possible to separate molybdenum from vanadium by application of anion exchange column.
Moreover, the methods of determining vanadium by N-benzoyl-N-phenyl-hydroxylamine and uranium by 1, 2-pyridylazo-2-naphthol were checked and improved, and these methods were applied to bittern and others with good results.

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多孔性のイオン交換膜を用いた海水の電解透析濃縮において, 取得かん水量が非常に影響することを認めたので取得かん水量を一定とし, 電流密度の生成かん水の濃度におよぼす影響について実験を行ない, 大要つぎの結果を得た.
1) 電流密度を増大すると生成かん水の濃度は高くなる.
2) 電流密度の増大にしたがい, 取得塩分量は増大するが, それに対応するだけの塩分は得られず, 見掛けの電流効率は低下する.
3) 電圧は電流密度に対して大体比例して増加するが電力量は増大する.
4) 以上の結果から, 海水の濃縮を行なう場合にあまり透水性の大きな多孔性のイオン交換膜を使用することは高濃度のかん水を得難いから工業的に有利な方法とは考えられない.

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Dowex A-1とポリ塩化ビニールよりなる不均質膜を用い, その電気抵抗の測定とNaCl-CaCl2系における電解透析実験を行ないNa⁺とCa²⁺との透過性について検討した.
この結果, かかるキレート膜の膜抵抗は塩化カルシウム溶液中では低濃度で急激に増加しその割合は溶液のそれに比例し, 塩化ナトリウム-塩化カルシウム溶液中のそれはカルシウムの存在によつてかなり増加する.
また, 電解透析によるNa⁺とCa²⁺の移動量の比, すなわち選択透過係数はカルシウム含有量に無関係でその値は約1を示した.しかしながらCa²⁺の存在によつてカチオンの輸率は減少し, カチオン選択性が認められなくなる傾向がみられた.
本試験の実施にあたり御指導をいただいた当場場長諏訪小一郎氏および次長清水和雄氏, 御協力を受けた電気課長鈴木清氏に深甚なる謝意を表します.

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We tested the effect of salt on the permeability of compacted granite soil, and obtained the following results.
Soil permeability is decreased remarkably by salt. For example, when the soil is compacted at a given moisture less than optimum moisture content, the degree of its permeability becomes about 1/7 by adding 1.7% salt to dry soil.
The most effective quantity of salt for decreasing the soil permeability is the quantity required to just saturate the soil moisture.

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Vol. 15 (1962) No. 5-6 p. 263-264

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