The following are the results of my study on a certain yellow species of the Yamagata bentonite.
(1). A water imbibing mass at the swelling equilibrium (25.0°C) contains 0.359g of dry clay per 100g of the mass, and its calculated values of sp. volume and swelling ratio are 0.980cc and 1:73.0 respectively.
(2). On adding ample water an abnormally rapid swelling is observed on the surface of a dry or partially imbibing clay mass. Let us call the swelling “surface swelling”. The surface swelling, with some quickness, takes an equilibrium which correspond to a terrace, nearer to the origin, on the time-swelling curve, and leaves a gelatineous thin film on the surface, a film completely covering the surface, insists against further penetration of water. A time interval to reach the equilibrium of the surface swelling becomes shorter both with the increase of initial distribution density of surface particle and with dryness or concentration of the mass of clay, and yet the gel film thickens with the shortened time interval just mentioned.
(3). A film of bentonite, 0.1-0.05mm thick, does a directional swelling, viz., at the swelling equilibrium the ratio of swelling is 1:39.0 in the direction of thickness and 1:1.37 in that of spreading.
(4). The swelling velocity of film, in both directions, may well be denoted by the following equation:
di/dtk(i∞-i_t)
Here, it is a ratio of swelling at any time interval t, and i_∞ another at infinite time, k being a constant of proportionality. This equation is quite the same as that of simple chemical reaction velocity.
(5). On considering a mechanism of film formation we can infer a type of bentonite micelle model. The model has a layer structure which can be exemplified by a alternative film layer of Al-hexite an Si-hexite, and it has almost the same structure as the crystal structure of kaolinite or some base-exchange type clay.

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1. Author carefully observed a cement rotary kiln from its outside to investigate of the gas flow mechanism in it.
2. Under a normal running condition, CO₂ content in the raw meal in a cement rotary kiln diminished by ca. 10%, owing to its residual heat in the kiln stoped.

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To find out the effect of auxiliary constituents of magnesite refractories such as silica, alumina, ferric oxide, and chromic oxide on the modulus of elasticity of the refractories, experiments have been made on the modulus of those bricks which are chiefly composed of these constituents. Test pieces, 1.5cm thick, 2cm wide, and 12cm long, have been cut from 2 brands of grog brick, an agalmatolite brick, an aluminous brick, viz. a bonded Corhart brick, and a chromite brick. These have been tested for the relation between central load and deflection at room temperatures and also deflection and modulus of elasticity at ordinary and higher temperatures up to 950°C. Besides, microstructure and linear thermal expansion have been examined and discussions are given on the relation between the modulus at room temperature and microstructure and that between the modulus at high temperatures and coefficient of linear thermal expansion. The results may be condensed as follows:
(1) The relation between the load and deflection at room temperatures is almost lineal for these refractories.
(2) Modulus of elasticity at room temperatures is highest with the aluminous brick. That of the chromite brick is a little lower. With the grog and agalmatolite bricks, it is only 1/7 to 1/13 of that of the aluminous brick.
(3) There exists a close relation between the modulus at room temperatures and microstructure. Althouth the aluminous brick has a structure similar to the grog bricks, its grog grains are compactly built up of interlocking crystals and glasses and are tightly bound on account of the high forming pressure and the high firing temperature. The chrome brick has also a compact and firm structure. Residual quartz grains in the silica brick have many cracks. In the grog and agalmatolite bricks, bonding between each grain is weak; Their quartz grains have no crack
(4) The modulus of elasticity is proportionate to the compressive strength, though variation in the former is greater than in the latter.
(5) There is an almost linear relation between the modulus and porosity in the grog and agalmatolite bricks.
(6) The deflection of the silica brick increases rapidly at temperatures ranging between about 90° and 230°C, especially at the inversion temperatures of tridymite, i.e. 117° and 163°C, and falls suddenly at 230°C. It decreases gradually at about 280°C and up, falls rather rapidly at about 550°C, and thereafter is almost constant. The curves of the grog and agalmatolite bricks resemble this; However the change at about 90° to 280° is not so marked and the deflection begins to rise rapidly at about 700° to 800°. With the aluminous and chrome bricks, there is no marked change in the deflection up to about 750° where it begins to rise rapidly.
(7) The result of the accurate measurement of the coefficient of linear expansion on heating these refractories at a constant rate indicates that the deflection increases rapidly only in process of silica inversion and gets true value on its completion.
(8) It is likely that the rapid rise of the deflection or the rapid fall of the modulus at about 700° to 800° and up with the grog, agalmatolite, aluminous, and chrome bricks owes to the softening of glasses contained in them.

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