In the preceding report the author have mentioned the relations among the various kinds of precipitated CaCO₃ crystals, namely globular, rhombic, flowery and needle shaped forms, which were obtained by adding (NH₄)₂CO₃ solution to the solution of CaCl₂.
The present paper concerns with another method of preparing CaCO₃ and with the conditions of the appearence of globular and other unstable form as well as the process of the growth of above crystals.
X-ray diffraction method and microscopic observation were jointly used for the identification of the polytypism.
The results are summarized as follows:
1) It was observed that the flowery and needle shaped type grew from the globular type μ-CaCO₃ as shown by the photographic records.
2) The necessary condition for the appearnace of unstable types seems to be the existence of the momentary local supersaturation of Ca²⁺ and CO₃^2-.
3) The appearance of aragonite type crystals was disturbed by the addition of the salts which increase the solubility of CaCO₃.

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The ice-point depression due to thermal after-effect of a thermometer glass reflects upon the fact that the density of a glass quenched from a certain holding temperature is always lower than that of the well annealed specimen even if the holding temperature lies in the region being considerably lower than the transition point.
From the results of the investigations made with lead glasses containing Na₂O, K₂O or both, which presumably show a strong thermal after-effect, the author concluded that the phenomenon is independent of the thermal history of glasses within the limits of experimental errors. Moreover it was found out that the appearance and disappea rance of the density change due to the thermal after-effect is reversible if the effects of compacting may be excluded.
The thermal expansion curves of rapidly cooled glasses showed hysteresis phenomena due to the release of the thermal after-effect. Hence the author was able to draw the curves showing the relations between the degree of the release of thermal after-effect and the reheating temperature.
The thermal expansion curves of the samples with various thermal histories, but free from both compaction and thermal after-effects were also obtained. Furthermore, the relation between the density change and the holding temperature were compared for many glasses having considerably different compositions and properties.

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This is the first report of the studies on titanium carbide cermets carried out by authors, which already have partly presented in 1955 at the general meeting of the Japanese Ceramic Association. Although there are some data necessary to be revised on reference to the later results the authors ventured to present them in the original form, since this paper concerns mainly with the authors' attitude toward the problem as well as with the methods of investigations.
At first, the reason why the authors have used a hydrogen-molybdenum furnace is explained by comparing the properties of the specimens obtained by sintering, respectively, in vacuum high frequency induction furnace and in a Tammann's furnace in hydrogen atmosphere.
Then the flow sheet of the process are illustrated, explaining the apparatus and equipments used for crushing, mixing, pressing and sintering.
Finally, the methods and apparatus for testing the hardness and bending strength and also the results of the microscopic observations are discussed.

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Five samples of silicious rocks and three samples of the residue of sulphur smelting, those may be regarded as valcanic origin, were subjected, respectively, to chemical analysis, to the determination of soluble silica, and to lime absorption test. Also the expansion test in saturated lime water as well as in distilled water have been carried out.
The residue of smelting sulphur was found to have 70% of soluble silica and 10-16% of soluble Al₂O₃ and Fe₂O₃, while the silicious rocks were composed almost exclusively, i.e. 90-95%, of soluble silica containing only the small amount of Al₂O₃.
Lime absorption of the residue of smelting sulphur showed at the first rapid, and then the very low increase, while that of the natural silicious rocks increased with rising inflection although the initial values were comparatively small. The expansion in saturated lime water run parallel with the results of the lime absorption. In distilled water, however, no change of length was observed.
Using the mixture of 90% of portland cement with 10% of the sample powder 1:2 mortar specimens were prepared by the method given in JIS R 5201. It was confirmed that the admixtures gave the very good results showing larger strength than portland cement in the 6 month's test. Especially, the residue of sulphur smelting, which contains large quantity of soluble alumina and silica may be regarded as being very promissing since it helps to develope high initial as well as long time strength.

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