α型半水セッコウ中のクエン酸を定量するため, HPICEモードおよびHPICモードを使ったイオンクロマトグラフィーの分析条件を検討した。
HPICEモードでは, 大きな硫酸イオンのピークが小さなクエン酸のピークに重なり, クエン酸の量を定量できなかった。
HPICモードでは, 標準の分析条件の場合, 10あるいは1mg/lのクエン酸に対してイオンクロマトグラムはなんらの応答も示さなかった。高濃度の溶離液と短かい分離カラムを採用することにより, クエン酸の電気伝導度による検出感度を高めた。そうすると, たとえ1400mg/lの硫酸イオンが共存していても, 1mg/lのクエン酸を定量できた。
媒晶剤としてクエン酸ナトリウムを使って亜硫酸カルシウム半水塩より作製したα型半水セッコウ中のクエン酸の量は約0.5 wt. %であることがわかった。

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As a basic study of phosphate removal from waste water by lime addition, effects of fluorine on apatite formation were studied. When milk of lime was added rapidly to phosphoric acid solution (P₂O₅ about 1, 000 mg/l) containing stoichiometric amount of F, fluorapatite with nearly theoretical mole ratio formed, while when milk of lime was added slowly calcium fluoride and amorphous calcium phosphate formed resulting in higher P₂O₅ content of the filtrate. When milk of lime and the acid solution were reacted continuously, a large portion of F stayed in the liquid phase, resulting in the pH raise and the formation of amorphous calcium phosphate.
When fluorine was not added, amorphous calcium phosphate first formed, which crystallized into hydroxyapatie. The amorphous calcium phosphate was more soluble than fluorapatite at an equal pH. The solubility of hydroxyapatite formed by 6 months aging was close to that of fluorapatite.
Tests made with weaker solutions containing about 100 and 10 mg /l of P₂O₅ gave different results.

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The crystal shape of calcium hydroxide (Ca (OH) ₂) is characterized by hexagonal plate-like crystal in the same way as that of kaolinite clay. The calcium hydroxide could be expected as new raw material instead of the clay for inorganic filler in paper, plastics and rubber. In the present work, attempts were made to investigate the effect of synthetic conditions of the CaCl2-Na OH reaction on crystal forms such as size, shape and homogeneity of Ca (OH) ₂ crystal, the most suitable synthetic conditions for artificial control of the crystal forms were clarified.
The homogeneity of crystals was mainly influenced by the rate of dropping NaOH solution into CaCl₂ solution, and the rapid dropping of 200 ml/sec found to be effective. The crystal size and shape were easily controlled by the concentration and the temperature of reactant solutions. At the temperature 20°C, the concentration above 0.5 N gave fine crystals below 1 μm and the concentration below 0.25 N gave truncated crystals of hexagonal pillar of about 3×6 μm. At the temperature above 50°C, the crystal consisted of hexagonal pillar with the developed (001), (010) and (100) faces but the crystal size changed to fine particle as the result of decrease in solubility of Ca (OH) ₂ at high temperature.
The controls of thickness and width of Ca (OH) ₂ crystal were made easily by dropping NaOH solution into CaCl₂ solution containing methanol. That is, the thickness of the hexagonal pillar-like crystal was controlled without changing plane width of the crystal as the result of friction of (001) face in layer structure by adding methanol and then the width of the plate-like crystal was controlled by changing the synthetic concentration and temperature. It made possible to synthesize homogeneous crystal with thin hexagonal plate.

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Moiré fringe method was applied to observe the concentration gradient of aqueous solution in C₃S solid and each kind of solution such as pure water, saturated gypsum solution and surfactants solutions. This method can detect exactly quickly the concentrative gradient caused by the dissolution of C₃S, the crystal growth in aqueous solution, and further the transfer of added surface active agent in solution.
In order to clarify the process of hydration mechanism of C₃S and each kind of solution, especially the effect of added surface active agents such as Mighty and Melment, we newly employed the micro amperometry in aqueous solution.
The fundamental hydration mechanism of C₃S after contact with pure water was supposed to attack of protons in water to oxygen atoms of C₃S, by proposing the model that crystal structure of C₃S has a solid basic catalyst effect by Ca-O bonds and a solid acid one by Si-O bonds. After quick proton attack, the concentration gradients are immedaetly formed bo the dissolution of C₃S and the diffusion of the soluble components into the solution.
The retardation mechanism of gypsum to C₃S hydration is shown by the transfer of the soluble gypsum component towards the surface of C₃S.
The effect of surfactant on the immediate hydration of C₃S can be explained by th experimental results that these surface agents quickly transfer to the surface of C₃S and consequently retard the formation of the concentration gradients of the solution.

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