An automatic recording apparatus which is possible to measure simultaneously the weight loss and contraction of samples during heating was constructed.
Sample and neutral substance were formed into cylinders by pressing, and the small e. m. f. due to the temperature difference was amplified for recording. Both, the change of weight and volume were measured electrically using a displacement meter of differential transformer type.
The compound thermal analyses of clays up to 1000°C was carried out with satisfactory results showing the perfect coincidence of the curves of thermal analysis, and those of weight loss and contraction by heating.

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Seeing that almost all properties of the portland cement can be attributed to some forms of linear combinations of proper functions pertaining to the mineral components in the clinker, we have to appreciate still the facilities of the recasting method. Although there have already been a number of proposals as to the recasting, we do not know yet any satisfactory procedure, however.
According to the opinion of one of the authors, attentions should be paid to the diadochic phenomena, which are universally recognized among the mineral worlds including the socalled artificial minerals, along with the proper recasting operations.
In the first place, we provided for the rudimentary data indispensable for the determination of n-value in the general formula C₆A_nF_3-n for the iron containing phase in the clinker, by means of the X-ray diffractograms. Conveniently enough we found that the d-values of some suitable hkl vary almost linearly with the n-values, as shown in Figs. 21-25, excepting those parts near n=2.
In the second place, we called our attention to the diadochic transfers of a few percentages of silicon into the alminum containing phases to realize the inversion in the proportion of the contents between C₃S and C₂S, which has long been the nuissance of the conventional recasting procedures as formerly pointed out by one of the present authors as well as by Eitel, Bogue and others.
With the incorporation of such considerations on the diadochy in general sense along with the proper recasting procedures as shown in Tab. 5, we could get results which were really competetive with those by the laborious and tendious microscopic mineral estimations as shown by the examples in the following texts.
The results of the present studies were already presented at the June Meeting (Tokyo, 1960) of the Japanese Ceramic Association.

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Studies were carried out for the purpose of finding out the range of compositions in the system Li₂O-ZnO-Al₂O₃-SiO₂, in which the change by rehearing to polycrystalline bodies occurs without acccompanying the defects as flaw and crease, and of measuring properties of the devitrified glasses.
The results obtained are as follows:
1) Changing the Li₂O content as 4, 6, 8, 12 and 16 against ZnO+Al₂O₃+SiO₂=100 the range, in which the batches may be melted at 1300-1400°C to clear glasses and produce perfect polycrystalline specimens by reheating, was determined.
2) Occasionally, above specimens supported by two knife edges deformed by their own weight during the reheating. When Li₂O content was as low as 4, 6, 8 the amount of ZnO has proved to be most influential in the deformation, and it was confirmed that such trend was becomming smaller with the increasing amount of ZnO.
3) The differential thermal and X-ray analyses have disclosed that from the specimens of low Li₂O (4, 6, 8) the primary crystals were ZnO-compounds such as 2ZnO⋅SiO₂, while from those of high Li₂O the primary crystalline phase was composed of lithium compounds such as Li₂O⋅2SiO₂.
When the repeating was carried out at higher temperatures, i.e., 50-100°C below the deformation temperature of polycrystalline specimens, the crystals were composed of willemite, β-eucryptite, β-spodumene, cristobalite, quartz, and lithium mono- and di-silicates, having the size of 1-2μ measured under microscope.
4) The bending strength of polycrystalline specimens changed in a high degree by composition (Fig. 4., Table 5). Although there seemed to exist no simple relation between the composition and the bending strength, the values of those of low alkali (Li₂O=4, 6, 8) and Al₂O₃=0 gave the exceptionally low values, which probably due to the existence of minute hair cracks came from the abnormal volume change at around 250°C of cristobalite formed in large amount in the specimens during the repeating.
5) The amount of Al₂O₃ produced a large effect on the thermal expansion of the specimens in the composition range given above. There was a trend that the expansion coefficient became smaller with the increase of Al₂O₃ content (Fig. 5 and Table 6). Especially, high Al₂O₃ glasses containing small amount of Li₂O (=4 and 6) gave the products having exceedingly low expansion coefficient (5.4×10^-7). The specimens of Al₂O₃=0 have larger expansion coefficient. This may be interpreted by the formation of cristobalite having large expansion coefficent instead of β-eucriptite which lowers the expansion of devitrified products.

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It is known that stoichiometric compositions of the urania-thoria system form a series of continuous solid solutions having some better properties as a nuclear ceramic fuel than urania only in oxidation resistivity, refractoriness, and usefulness of thoria as breeding materials. The sintered bodies of thoria-rich portion in the system have been studied since 1956-7 in Argonne National Laboratory, and subjected to the reactor tests, and going to be applied to fuel materials of power reactor.
The authors have already published the results on the oxidation resistance and the sintering of the urania-rich portion of this system. This paper is concerned with their sinterings in air and reductions to stoichiometric compositions.
The starting materials were the products of firing in air the coprecipitated mixtures of ammonium diuranate and thorium hydroxide obtained from mixed nitrate solutions of uranium and thorium by adding ammonia solution. The variation of pH by adding ammonium hydroxide to the mixed nitrate solution is shown in Fig. 1, and the calcination processes of the coprecipitates in air were traced by means of the thermogravimetric balance, with the results as given in Fig. 2. The tapped densities and Blain values of the calcinated powders in air at 800°C for 2 hrs. were measured, and also subjected to X-ray diffraction test. The results shown in Fig. 3 indicate that the grain size of he powders of containing 10-30% ThO₂ are very small because of the hindrance of the crystal growth in the mixed phase of U₃O₈ and solid solution. The content of U₃O₈ phase has decreased and that of solid solution of fluorite type has increased as thorias were added to urania. U₃O₈ phase has disappered in the compositions containing thoria more than 60 weight%, forming only the solid solutions.
The powders calcinated in air at 800°C were pressed at 3tons/cm² to pellets of about 10mm in diameter, and sintered in air and reduced by CO gas. The results are given in Fig. 4 which show that the compacts containing 10, 20, and 30 wt.% of thoria have perfectly sintered at 1400°C, and those with 50% of thoria at 1500°C. The reduction of sintered pellets to stoichiometric composition by CO gas could be made more perfectly at higher sintering temperature, but the specimens containing less than 10% of ThO₂ have cracked, as given in Table 1.
The calcinated powder containing ThO₂ 30% was too fine to be pressed, and therefore the raising of calcination temperature up to 1000°C was tried. The sintering of these specimens showed a good results with the powder calcinated at 1000°C (Table 2). On the contrary the powders containing ThO₂ 50% was difficult to sinter at 1400°C, but this was possible by using the powder calcinated at 600°C (Table 3).
The sintering in air of the uranium-rich specimens showed some faults of the volatilization of uranium component accompanying a large dimengional change at the reducing step. Therefore, the sinterings in neutral atomosphere, followed by hydrogen reduction were made at 1300°-1400°C. These sintering properties showed no particular differences between the atomosphere of nitrogen and carbon dioxide, and it was confirmed that good results may be obtained when the samples of 70-30 and 50-50 stoichiometric composition are sintered at 1400°C. The sintering processes will be reported in a following paper.

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