The viscosity of the Yamagata-clay sol is measured with the capillary method and with the falling-body method as well; and some anormalisms of it, the relation of viscosity-temperature and that of viscosity-concentration, the specific hydrodynamical volume of colloidal particle have been studied, a model of particle formation being finally inferred. The following is the brief summary of the present investigation.
1. The dense sol of the clay shows some anormalous viscosities. The structural viscosity of the sol is a indication of any gel structure. The structure is easily broken with a small shearing stress exerted by the flow head of capillary, causing the serious apparent viscosity drop. Yet the broken structure of the sol shows a self-curing ability and recovers slowly but almost completely the original structure, that is the so-called thixotropism. Moreover, there is a very singular anormalism, i.e., when the falling-body method is applied, the apparant viscosity of the sol gradually increases with increasing path of the falling-body.
2. There is the following relation between the relative viscosity, of the thiner sol and the concentration, c, in grams per 100cc of sol:
logηr=αc+βc²
where α and β are the empirical constants. But in case the sol increases in concentration, the estimated value of ηr becomes larger than is shown in the above equation.
3. When sol is thin, the temperature effect to viscosity is denoted by the following equation, that is the same as that given by Poiseuille for pure water:
η_t=η_o/1+pt+qt²
where η_t and η_o are viscosities at t and 0°C respectively, p and q being the empirical constants.
4. The specific hydrodynamical volnme, φ, of the clay in sol is calculated with the following viscosity formula, which was presented by I. Sakurada recently for celullose sol:
η_r=η_c/η_o=1+aφc/100-φc
Here ηc and η₀ are the viscosity coefficients of sol and simple medium, accordingly the ratio of them, η_r, the relative viscosity; c, the concentration in grams per 100cc of sol, and a is a constant called ‘Form und Ladungsfactor’ by Sakurada. The average value of φ for Yamagata-clay is 32.5cc per 100cc of sol, which contains lg of dried mass, covering the temperature range 10-35°C. This figure of φ shows that the swelling ratio of the clay is roughly 80. The value of φ has a slightly decreasing tendency with increasing temperature.
5. The particle suspending in dilute sol must be a fragment of the gel structure. It seems to does some visco-elestic but not plastic deformation by any stress, and moreover to be a complex grouping of some flexible chain-like aluminosilicic molecules. Besides, every heavy molecule or unit micelle must have dense and less-mobile liquid layer or ionic swarm on and near the surface, only that mobility quickly increases outwardly

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Continuing the previous studies in cooperating with Kichinosuke Fukai (this Journal, 1934, 42, 339, 471 1935, 43, 55), one of the present authors S. Nagai has again farther studied on the steatite refractories in cooperating with Giichi Inoue, by using other samples. Some results were preliminarily reported in the present paper. The brief summaries are abstracted from the original Japanese paper, as following:
(1) Raw materials were again collected, i.c., (a) Talc samples from Manchoukuo, (b) Serpentine samples in Japan, (c) Shuganseki sample of Bowenite or Meerschaum type from Manchuokuo, & Korea etc., and these samples were tested on their chemical compositions and specific gravities. The results are shown in the following table 1.
From these results, the rational formulae xMgO·ySiO₂·zH₂O were calculated by making y of SiO₂ as round number and obtained the following results: Talc E: 3MgO·4SiO₂·1.5H₂O, Talc F: 3MgO·4SiO₂·1.1H₂O, Talc G: 3MgO·4SiO₂O·9H₂O, Talc H: 3MgO·4SiO₂·1.0H₂O, Talc I: 3MgO·4SiO₂·1.0H₂O, Shuganseki B: 2.9MgO·2SiO₂·1.9H₂O, Serpentine D: 3MgO·2SiO₂·2H₂O, and Serpentine E: 2MgO·SiO₂·1.5H₂O. These results show that the present samples are of good quality having the theoretical formulae of magnesium hydrosilicates talc, serpentine, etc. But the samples of serpentine D and E are of a little lower grade cont:ining a little larger amounts of alumina and iron oxide impurities.
(2) By using the talc sample E, several series of tests were systematically carried out. The test pieces were moulded to small plate (Length: 60mm, Bredth: 30mm and Thickness: 5-10mm), by pressing with oil press, applying various pressures 100-700kg/cm² without water, which was quite different from those moulded with water in the previous reports I-III. The moulded pieces were not necessary to dry and then at once burned at 1300-1500°C for 2-6 hours. The test pieces were strictly compared on varous points, i.c., drying and burning shrinkages, specific gravities, porosities, mechanical strength (bending or transverse strength, or modulus of rupture). The results are shown in the following tables.
It is clearly seen from these results that the physical property of bending strength became greater proportionally to the higher moulding pressure, and the porosity was considerably small in the samples of higher moulding pressures. These results are far better than those of samples moulded with water in the previous papers I-III, owing to the moulding process without water.
(3) As plastising materials, magnesium chloride of 12% water solution and boric oxide in powder were used, and the moulding and testing were quite equally carried out as those above explained. The results are tabulated in the following table 3.
The addition of small amount of magnesium chloride or boric oxide gave good results, e. g., higher bending strength and smaller porosity, especially in the samples moulded by higher pressure 400-700 kcm². But on the contrary, these plastisers gave bad effects to the products. The test pieces expanded and lowered the strength by storing in the air for three months, esperially the sample MR60-2 moulded by the addition of borax considerablly expanded and disintegrated.
(4) Nextly, free magnesia and silica were mixed in the molecular ratio of natural magnesium hydrosilicate minerals of talc, serpentine, merrschaum, etc., and moulded with or without water. For this purpose, caustic or light burned magnesia and Keisanhakudo (siliceous white earth, natural product in the province of Ishikawa, containing large amount of

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A study was made of chemical changes in the Cottrell cement dust due to indoor or outdoor weathering for 80 days, pyrometric cone equivalents of system silica-dust and system feldspar-dust, and devitrification phenomena of system silica-soda-dust. Besides, the field producing faultless glass in system silica-soda-dust was determined more precisely than in the preceding report. Conclusions are as follows: 1. The slight but abrupt loss in weight shown in the heating curves of the weathered dusts at about 250°C owes probably to the decomposition of 3MgCO₃·Mg (OH)₂·3H₂O. 2. Each P. C. E. curve of the system silica-dust and the system feldspar-dust has a maximum and two minima. It is probable that wollastonite is formed mainly at the maxima. 3. The utilization of the dust is 50% or less when quartz is used.
4. Well developed crystals in the devitrified glasses are fibrous and each fibre is surrounded by a black glass which reduces nD of the crystal mass. The nD are very near to those of R₂O·3CaO·6SiO₂. However, the crystals are surely wollastonite because their X ray diffraction patterns coincide precisely.

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