In the present paper were reported the results of various studies on utilization of byproduct gypsum material, which are called as “Gomi” and “Scale” and have the main compositions of NaCl and CaSO₄ mixed with MgCI₂, KCI, MgSO₄, K₂SO₄, Na₂SO₄, etc. These gypsum containing byproducts were firstly washed with sea water or dilute brine to dissolve and exclude NaCI and other salts above mentioned. CaSO₄ in these byproducts “Gomi” and “Scale” was proved to be of anhydrour form, which is called as soluble anhydrous gypsum, owing to the high boiling temperature in the concentrated brine solution. This soluble anhydous gypsum (CaSO₄) changed easily to the crystal gypsum (CaSO₄·2H₂O), by treating with dilute NaCI solution, which is the dissolving solution to separate out NaCI, KCI, MgCI₂, MgSO₄, K₂SO₄, etc. above mentioned.
Crystalgpysum (CaSO₄·H₂O), thus obtained, was mixed homogeneously with calcined dolomite powder and slaked with proper amount water, and obtained special gypsum dolomite plaster (called by the present authors as “Gypster”), by the following equation. This special gypsum dolomitegypster (Gypster) was proved io be superior plastering material, x (CaSO₄·2H₂O)+(1-x)(CaO+ MgO)+y H₂OxCaSO₄·1/2H2O+(1-x)[Ca(OH)₂+Mg(OH)₂] by various testing methods of various plasters.
This purified crystal gypsum or its cr ude raw material “Gomi” or “Scale” was mixed with raw dolomite in proper proportion and this mixture was calcined at about 900°C and then slaked with water of proper amount to special gypsum dolomite plaster. This poduct was also proved to be useful as plastering material of superior quality.

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We tried a gravimetric method using centrifuge instead of volumetric methods using centrifuge for rapid analysis of salt. This method can be summerized as follows: The sample solution is added with precipitants in a 15ml centrifugal tube and the formed precpiitate is separated by the centrifuge from the supernatant liquid. The liquid is thrown out, then distilled water is added. After vigorous stirring, the centrifugal precipitating operation is carried out and the precipitate is washed similarly with alcohol and ether respectively. Finally, the precipitate is separated by the centrifuge, dried and weighed with the tube. We applied these procedure for the analysis of insoluble matters, Cl^-,SO₄^2-, Ca²⁺, Mg²⁺, K⁺ and Na⁺ in common salt, and compared the results with that of the official method of Japan Monopoly Corporation, and found that our method is practically applicable for the rapid analysis of common salt, brine or bittern.

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In the concentration of brine by multiple effective vacuum pan, each components were estimated.

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Characteristic aging property of soft polyvinyl chloride sheet was indicated by means of creep behaviour and the constant of the theoretical state equation of rubber elasticity derived from the Stress-train curve which obtained from creep curves. The agreement between experimental and theoretical strees-strain curve is good. This constant appears to be good susceptible of aging process.

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It was determined by considering the number of molecules in a unit cell of basic magnesium carbonate that the composition was 5 MgO·4CO₂·5H₂O. The other compositions reported previously are those of basic magnesium carbonate which containe as impurities: MgCO₃·3H₂O, Mg(OH)₂ and amorphous material. CaCO₃ in basic magnesium carbonate manufactured by different process is found in the type of calcite or aragonite. From the point of the use of this material, the state analysis of basic magnesium carbonate by X-ray diffractometer is more useful than ordinary chemical analysis, and the method was examined.

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In this study, it was found that in crystalization from the solution, if small quantity of sodium hexametaphosphate (NaPO₃)₆ is added into the solution, it behaves to promote the growth of crystals (namely to enlarge the crystal particles). And especially in crystalization of NH₄Cl from the solution by cooling, the action of (NaPO₃)₆ above mentioned was investigated. Result obtained:
(1) The action of (NaPO₃)₆ added into the NH₄Cl solution is more efficient than that of Mn²⁺which has been used for the same purpose.
(2) Adding of (NaPO₃)₆ is more effective than that of the sodium polyphosphate Na_n+₂P_nO3_n+1 usage of which was also attemped by the author.
(3) Simultaneous using of (NaPO₃)₆ and Mn²⁺ is more effective than individual use of those respectively.
(4)(NaPO₃)₆ in the solution acts efficiently when the solution is gradually cooled.
(5)(NaPO₃)₆ being decomposed by heating the solution beyond 80°C, its role is reduced, therefor it must be added below such the temperature.

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This study was an attempt to determine by simple method the value of calcium in the sea water by applying methyl oxalate. By the method already known to us, we often see an increase in quantity of magnesium in the sea water owing to its post-precipitation. Its re-precipitation is necessary to get the true value avoiding this increase of magnesium at the same time. Through this method, le can get the correct value much simpler and more exactly without any disturbing influenc es as mentioned above.

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By means of solving the mechanism of evaporation in the multi-vertical flow system concentrator, it is possible to discuss the increase of evaporating velocity and the decrease of cost of construction. The authers have solved the formula of evaporating velocity by unit of cylindrical liquid surface in the descending liquid temperature, measuring the distribution of liquid temperature and utilizing the analogy of the flow and the vapor diffusion. The results concided with experiment. The results were followed:
1) The formula of evaporating velocity by the theory of boundary layer.
2) The formula of evaporating velocity by the analogy of heat transmission and mass transfer,
The 2 nd formula has showed more good agreement with experimental values than 1st at range Re≤50.

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The refractivity of common salts was measured from 400-720 mμ of wave length by the Shimadzu photoelectric spectrophotometer, and Judd's whiteness W_Jwas calculated. With a simple apparatus, Ashirnori AEW-I, the refractivities of the same samples were measured through the red and blue filters respectively, and from those values whiteness W_A was determined applying the following equation;
W_A=50+(R+B)/4-k(R-B)
here R, B; refractivities through red and blue filters respectively. Judging from Spearman's method, W_A value accorded with W_J and with visible comparison.

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[in Japanese]

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