Volcanic glass is main component of Shirasu. Therefore it is thought that properties of volcanic glass determine properties of Shirasu. Then the volcanic glass was separated with producing hollow microsphere glass from Shirasu and tested on chemical, physical, thermal, and optical properties. The results are summerized as follow;
1) Chemical compostion of volcanic glass in Shirasu is 0.23-0.61% Ig. loss, 74.66-76.42% SiO₂, 12.20-14.06% Al₂O₃, 0.60-1.63% Fe₂O₃, 1.35-3.42% CaO, 0.36-0.90% MgO, 3.00-4.00% Na₂O, 2.82-3.50% K₂O. Volcanic glass has less component in Ig. loss and Fe₂O₃ and the other hand more content in SiO₂, CaO and alkali as compared with Shirasu.
2) Negative relationship was observed for the each content of Al₂O₃, Fe₂O₃, CaO, MgO, Na₂O, and K₂O to SiO₂ content in volcanic glass and similar result was obtained in the case of Shirasu. Ig. loss contents of volcanic glass and Shirasu have a positive relationship to each other.
3) The thermal expansion of volcanic glass increases linear and softens at 840-940°C. The linear thermal expansion coefficient between room temperature and 800°C on the average is 4.0-4.6×10^-6/°C. The specific heat of volcanic glass is 0.19cal/g⋅°C on the low value in comparison with commercial glasses.
Refractive index of original volcanic glass (before forming the hollow microsphere) in Shirasu shows a value of 1.498 and the index in volcanic glass (after forming the hollow microsphere glass) shows a value of 1.486.
4) The alkali component in volcanic glass shows insolubility of ten times as compared with commercial glasses.

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The system ZrO₂-Y₂O₃ was investigated at 1000kg/cm² under hydrothermal conditions. The mineralizers used were redistilled water, 15mol% NaOH, 15mol% KOH, 5mol% Na₂CO₃, 10mol% K₂CO₃ and 6N HCI solutions. Fifteen mol% NaOH solution was the best accelerator to form well crystallized cubic zirconia solid solutions. The single phase region of cubic zirconia solid solution at 1000kg/cm² was more than 14mol% Y₂O₃ at 900°C, from 13 to 31mol% Y₂O₃ at 1000°C, from 10 to 34mol% Y₂O₃ at 1200°C and from 6 to 45mol% Y₂O₃ at 1400°C, which was narrower than that at 1 atm in air. The results suggested that the phase relation between ZrO₂ and the stabilizer has to be determined before hot-pressing cubic zirconia.

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The investigation on the relation between the heat of solution in R₂O-GeO₂ crystals obtained from solution calorimetry and the change of germanium co-ordination number with composition were carried out. The data previously reported were used in the present discussion together with the data obtained by the present work.
The results are summarized as follows:
1) The break points were observed in the composition dependences of heats of solution, which were well represented by segments, one in each system of Li₂O-GeO₂ and Na₂O-GeO₂ and two in K₂O-GeO₂ system. The break point compositions correspond to those of the congruent melting compounds Li₂O⋅7GeO₂, 2Na₂O⋅9GeO₂ and 3K₂O⋅11GeO₂ in each system. In K₂O-GeO₂ system, the other break point corresponds to the K₂O⋅2GeO₂ compound.
2) Based on these energy relations and some known crystal structures of germanates, the fraction N_G6 of germaniums that are six-co-ordinated to oxygens as a function of composition U=mol% R₂O/mol% GeO₂ was derived as follows.
As N_G6 equals 2U, it increases linearly with U until the maximum value, 0.28, 0.44 and 0.54 in the system Li₂O-GeO₂, Na₂O-GeO₂ and K₂O-GeO₂, respectively. When U increases further, in the systems Na₂O-GeO₂ and K₂O-GeO₂ N_G6 decreases linearly as shown by the following equations.
Na₂O-GeO₂: N_G6=-0.56U+0.56 (0.22<U≤1.0),
N_G6=0 (1.0<U)
K₂O-GeO₂: N_G6=-2.35U+1.18 (0.27<U≤0.50),
N_G6=0 (0.50<U)

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The method of the determination of molybdenum in glass was investigated by thiocyanate-stannous chloride extraction and X-ray fluorescence spectrometry.
The effect of diverse elements containing in soda-lime and borosilicate glass on the thiocyanate-stannous chloride method was investigated, and in the range containing ordinarily in commercial glass almost all elements except iron did not interfere the determination of molybdenum.
Color development of molybdenum thiocyanate complex was enhanced by the presence of iron, but up to the presence of a certain amount of iron, the color development was saturated. So it was proved that the effect of iron was compensated by adding a certain amount of iron to both sample and standard solution.
Considering the results obtained by the investigation about the effect of diverse elements and measuring conditions, the method of the determination of molybdenum in glass was decided as follows:
1g of powdered glass sample is taken to the platinum dish and decomposed with hydrofluoric acid and perchloric acid. The residue is dissolved by hydrochloric acid and the concentration is adjusted to 1.0N.
An aliquot containing less than 80μg molybdenum is transferred to a separatory funnel. 3.0mg iron and 10ml of 10per cent potassium thiocyanate are added and mixed. After one minute, add 5ml of 30 per cent stannous chloride and mix. After one minute, exactly 25ml of n-butyl acetate and shake vigorously for one minute and allow the phases to separate for 30 minutes. The absorbance of the clear n-butyl acetate extract at 460mμ in a 1cm cell.
Blank is run through the whole procedure. Standard curve is similarly established.
With this method 2.5 to 200ppm molybdenum in soda-lime and borosilicate glass is determined.
At the same time the X-ray fluorescence spectrometry was investigated. There is a linear relationship between the intensity of X-ray fluorescence of MoK_β and molybdenum content by chemical analysis mentioned above, and it is proved that 25 to 600ppm of molybdenum in glass is determined by X-ray fluorescence spectrometry.

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Hydrated alumina gel was synthesized by the homogeneous precipitation method from urea and aluminum salts, and the influence of anions in the aqueous solutions on the hydrated alumina gel was investigated by the continuous measurement of pH, the powder X-ray diffraction analysis and the microscopic observation.
When an aluminum sulfate was used, a superior filterable granular substance was obtained. On the other hand when an aluminum chloride or an aluminum nitrate was used, an inferior filterable gel-like substance was obtained, and the pH value of the precipitation obtained was about 4 in the former case and about 7 in the latter.
These products were confirmed by the microscopic observation that the granular substance has a globular form, while the gel-like substance was an indefinite form. Both gel-like and granular substance were amorphous according to the X-ray diffraction analysis.
From these results it was made clear that the hydrated alumina gels synthesized by the homogeneous precipitation method have different properties depending on the starting materials.

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TiO₂ (rutile) powder compacts with additions of various oxides were sintered at 1300°C in air to examine the effect of the additives on the sintering and the electrical resistivity. Additions of ZnO, In₂O₃, Fe₂O₃, Co₂O₃, and NiO accelarated the sintering, and produced high-density bodies of 95-96% of theoretical. Sb-oxide (added as Sb₂O₃), Nb₂O₅, and Ta₂O₅ which had negative effect on the sintering, reduced the resistivity about five orders of magnitude. None of these additives used, however, affected concurrently both of the sinterability and the electrical resistivity.
TiO₂ powder compacts containing 1-10wt% Sb-oxide were sintered at 1000-1400°C in the atmospheres of N₂, air, and O₂. Weight loss and X-ray diffraction data showed that Sb-oxide was soluble in TiO₂ up to about 7wt% at 1000°C in air, but that vaporization of Sb-oxide reduced the solid solubility at higher temperatures. Although the electrical resistivity of pure TiO₂ was strongly dependent on the sintering atmosphere (from 10³ Ω⋅cm in N₂ to 10¹² Ω⋅cm in O₂), TiO₂ compacts doped with Sb-oxide had relatively stable resistivity of 10³-10⁴ Ω⋅cm irrespective of the sintering atmosphere. For Sb-oxide doped TiO₂ compacts sintered in O₂, which indicated p-type semiconductivity, it is considered that ionized titanium vacancies and holes were the predominant defects.

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Siliconizing reaction was performed by vapor deposition of silicon on the basal plane surface of kish graphite kept at a given temperature from 900 to 1550°C at 10^-4 torr. Reaction product (cubic β-SiC) was analyzed by an electron diffraction, and the distribution of products was observed with a scanning electron microscope.
The results obtained were summarized as follows;
(1) Electron diffraction examination of the reacted surface, by a surface reflection technique, showed that microcrystalline silicon carbide was formed at a temperature as low as 900°C.
(2) The distribution of small β-SiC crystal which arose from vapor deposition of silicon at 1200°C revealed the microstructure based on defect site on the basal plane surface of kish graphite.
(3) Since the formation reaction of β-SiC proceeds at the defect sites on the basal plane surface, the value of - 10⁸cm^-2 was estimated as the density of defect on its surface by counting the number of products.
(4) The graphite crystal was siliconized from ‹1010› and ‹1120› direction, and the formed β-SiC showed some orientation relationship between the graphite when its thickness was less than 1000Å.

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Five fibrous materials, asbestos, glass fiber, rock wool, acrylic fiber and pulp fiber were tested as a reinforce for a molded material of xonotlite. Molded materials of xonotlite with those fibrous materials having bulk density of about 0.2g/cm³ were prepared by the slurry method. The textures of those molded materials before and after heating were observed by a scanning electron microscope. After heating at 1000°C, the organic fibers were burnt out and inorganic fibers except asbestos were melted.
The bending strength of the molded materials after and during heating were measured. The organic fibers produced high bending strength at the low temperature but it decreased after and during heating at high temperature. Asbestos produced always sufficiently high bending strength and glass fiber and rock wool had almost same nature in spite of their meltable property but they brought slight decrease of bending strength only after heating.
For the low temperature use, acrylic fiber is most available because of its toughness, while for the high temperature use asbestos is most available, and glass fiber and rock wool are also available in spite of having a little defect, some brittleness and meltableness.

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