高圧水銀灯の外管として使われ, 紫外線照射により応力を発生したテレックス及びパイレックスガラスを加熱した時の熱的緩和電流の特性を観察した. 損傷したままのガラスでは, 熱的緩和電流が見られる温度域が250°ないし500℃の間にあり, また試料ごとに異なっていて再現性がなかった. 試料を洗うと, この温度域が450℃附近の狭い範囲に局限され, また内表面あるいは外表面を削り落しても同様であった. しかし内外表面をともに削り落すと, 緩和電流が顕著に減少した. 緩和電流は電極面積1cm²当り10^-5-4クーロンの蓄積電荷に相当した. もしこれがガラス中の構成イオンの変移に原因するのであるならば, ガラスの構造ないし密度変化, 従って応力発生を説明するのに十分な量である. しかし, 電荷蓄積の原因として考えられるものがいくつかあり, 特に応力発生そのものが原因であるかも知れないので, この現象を完全に理解するには, さらに研究を必要とする.

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Creep deformation of sintered zirconium diboride were studied at 1690°-1890°C under compressive stress of 160-500kg/cm² using hot-press furnace. The samples for this experiment were prepared by hot-pressing and grouped into three porosities.
Deformation of zirconium diboride was remarkable above 1800°C. The higher load was applied, the more quick deformation occured. Deformation rates also increased with increasing porosity. But it's temperature dependences were independent of porosity and load. Activation energy for deformation was 100-120kcal/mole. Sintered zirconium diboride showed plastic behavior and yield loads were 130-160kg/cm² for samples with 19-20% porosity at the temperature range of this experiment. The effects of porosity and grain size on deformation rates were discussed. Viscosity calculated from this experiment was compared with that from densification experiment.

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Coral limestone resourses are very aboundant in Amami Islands, but a slight amount of the ore has been only used for chemical industrial materials.
The object of this paper is to describe the results of the writers' work on the fundamental properties of the coral limestone from Tokunoshima and Okierabushima, Kagoshima Prefecture.
Several samples of coral limestones were collected from the each terrace in Tokunoshima (8 terraces), and in Okierabushima (6 terraces).
Chemical analysis, X-ray analysis, determination of specific gravity, and various thermal tests etc. were conducted on these samples.
Slaking test and sedimentation test were also made on these coral limestones calcined at 950°-1100°C. Following results were obtained.
(1) Main mineral component in the coral limestone is calcite, often contains dolomite or quartz.
(2) Coral limestones of 32 samples have the following physical properties and chemical composition: apparent specific gravity 1.67-3.05, bulk density 1.64-3.38, apparent porosity 2.22-18.34%, moisture content 1.11-9.97%, and CaO 47.65-55.41%, MgO 0.10-3.52%, SiO₂ 0.11-10.52%, Fe₂O₃+Al₂O₃ 0.42-4.48%. The average value of CaCO₃ content of Okierabushima are is 94.73%, but the coral limestone from Tokunoshima is of poor quality with a purity of CaCO₃ 89.50%.
(3) It seems that the coral limestones located at higher terraces in Tokunoshima and Okierabushima have larger crystal size, larger thermal expansivity and more rapid thermal decomposition velocity than those of the coral limestones located at lower terraces, respectively.
(4) The effect of calcining temperature on the slaking velocity of calcined ore is governed by the chemical and physical properties of the original rocks. The stiff coral limestone including a slight amount of impurities calcined at 950°C is of good results, but the porous coral limestone including a large amount of impurities, i.e. SiO₂, Al₂O₃, Fe₂O₃ and MgO, has a slow slaking velocity at this calcination temperature.

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In order to make sintered body consisting of pure Si₂ON₂, nitriding reactions of silicon-silica system were studied experimentally.
The results obtained were summarized as follows:
1) When compacted mixtures of silicon and quartzite powders having mole ratios from 1.0 to 3.5 for Si/SiO₂ were heated at 1450°C for 3 hours in nitrogen atmosphere, sintered bodies containing Si₂ON₂ were obtained.
However, almost pure sintered body of Si₂ON₂ was produced from the mixture having the mole ratio of 3.0.
2) When compacted mixture of silicon and α-cristobalite, or fused silica powders in place of quartzite powder having the mole ratio of 3.0 for Si/SiO₂ was heated slowly and treated with nitrogen over 1400°C, similar sintered body of Si₂ON₂ were obtained.
3) The formation of Si₂ON₂ from the compact started at about 1100°C and was almost completed at the temperature range from 1400° to 1450°C.
4) Reaction of silicon, silica and nitrogen to form Si₂ON₂ was expected to proceed in two steps as follows:
1/2SiO₂+1/2Si=SiO
SiO+Si+N₂=Si₂ON₂
and reaction of silicon and nitrogen to form Si₃N₄ was not favorable to obtain pure Si₂ON₂ body, because it was rather difficult to change Si₂ON₂ from Si₃N₄.

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In all industrial ceramic tunnel kilns, the detail of flow pattern of kiln gases is one of the most important factors having a great influence on the kiln performance.
This paper presents the first report out of a series of the experimental research on the kiln characteristics from a viewpoint of the detail of flow pettern of gases in the ceramic tunnel kiln. An experimental hot model kiln constructed of firebrick having 3400mm length, 190mm height and 145mm wide was used to obtain data on the temperature and on the composition of the gases at various places in the kiln, from these data were deduced the relations between the characteristics of the fundamental flow pattern of gases and the principal dimension and the operation of the kiln.
The results obtained may be summerized as follows; (1) within the range of the Reynolds number higher than 6×10³, flow patterns have no striking variation against the change of the Reynolds number, (2) with slight resistance against flow of kiln gases at the upper part in the preheating zone flow of hotter gases converged into that place, (3) and when the kiln pressure was negative at the level of car top a large quantity of cold atmosphere was sunk into the kiln interior through the sand seal construction to give very uneven temperature distribution across the cross section in the preheating zone.

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