Bulletin of the University of Texas: Scientific series, 2. köide,12–17. number;12–16. köide

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University of Texas, 1908
 

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Page 58 - It is always well to put two or more cones of different numbers in the kiln, so that warning can be had, not only of the end point of firing, but also of the rapidity with which the temperature is rising. In...
Page 53 - Since some of the mineral grains in the clay are more refractory than others, the clay in the earlier stages of fusion can be regarded as a mixture of fused particles, with a skeleton of unfused ones. If the proportion of the former to the latter is very small there will be a strong hardening of the clay with little shrinkage, and the burned clay will still be porous. With an increase of temperature, and the fusion of...
Page 55 - For practical purposes these cones are very successful, though their use has been somewhat unreasonably discouraged by some. They have been much used by foreign manufacturers of clay products and their use in the United States is increasing. The full series can be obtained from Messrs. Seger and Cramer, of Berlin, for $0.01 each (or about two and one-half cents apiece, including duty and expressage), or numbers .010 to 35 can be obtained for $0.01 each from Prof.
Page 60 - Effects due to variation in the clay. — Burned clays may be of many different colors. Although the majority of clays contain sufficient iron oxide to burn red, nevertheless it is not safe to predict, from the color of the clay, the shade that it will burn, since some bright red or yellow clays may yield a buff brick.
Page 92 - Bies classes it as a very lean sandy clay whose physical properties were as follows : Color, when moist, white ; soluble salts 0.08 per cent ; water required 17.6 per cent, slakes fast ; plasticity low, with much coarse grit. The air shrinkage of the molded bricklets was 3.3 per cent and the average tensile strength 40 pounds, with a maximum -of 46 pounds per square inch. In burning it behaves as follows : I Cone: 05 03 1 3 5 9 31 32 mre shinkage per cent 0.1 0.3 vis.
Page 57 - ... but at the same time will not receive the direct touch of the flame from the fuel. It is always well to put two or more cones of different numbers...
Page 55 - F.). and the upper member of the series is cone 36, which is composed of a very refractory clay slate, while cone 35 is composed of kaolin from Zettlitz, Bohemia. A lower series of numbers was produced by Cramer, of Berlin, who mixed boracic acid with the materials already mentioned. Hecht obtained still more fusible mixtures by adding both boracic acid and lead in proper proportions to the cones. The result is that there is now a series of 58 numbers, the fusion point of the lowest being 590° C.
Page 58 - As a matter of fact, however, repeated tests with a thermoelectric pyrometer demonstrates that the cones commonly fuse close to the theoretic temperatures. Manufacturers occasionally claim that the cones are unreliable and not satisfactory, forgetting that their misuse may often be the true reason for irregularities in their behavior. It is unnecessary, perhaps, to state that certain reasonable precautions should be taken in using these test pieces. The cones are commonly fastened to a brick with...
Page 53 - ... be a strong hardening of the clay with little shrinkage, and the burned clay will still be porous. With an increase of temperature, and the fusion of more particles, the pores fill up more and more, and the shrinkage goes on until, at the point of vitrification, the spaces are completely filled.

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