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doi: 10.1111/j.1151-2916.1921.tb17310.xpmid: N/A
ABSTRACT A brief discussion of the theory of humidity drying is followed by a description of the construction and operation of a five room dryer installed above a tunnel kiln and supplied with automatic temp. and humidity control and air circulation. As compared with the older system having controlled air circulation only, the new dryer has been found to have the following advantages: (1) Reduced steam consumption; (2) 50% reduction in floor space; (3) 50% reduction in drying time; (4) Reduction in labor costs owing to elimination of a second handling of incompletely dried pieces; (5) Reduced losses from cracking and warping.
doi: 10.1111/j.1151-2916.1921.tb17311.xpmid: N/A
ABSTRACT It is possible through microscopic investigation of a silica brick to ascertain approximately the heat treatment to which it has been subjected. In this way the temperature difference between the inner and outer ends of a silica brick which had seen service in the arch of a Dressler tunnel kiln was estimated to be at least 200°.
doi: 10.1111/j.1151-2916.1921.tb17312.xpmid: N/A
ABSTRACT A method is described for determining the rate of sedimentation of clays by measuring the suspended weights of a glass plummet suspended in a clay slip at different intervals of time. The specific gravity of the slip remaining in suspension may be calculated as follows: S = Pd‐Ps/Pd‐Pw where S is specific gravity of slip, Pd is dry weight of a plummet in grams, Pw, is suspended weights of plummet in distilled water and Ps, is suspended weight of plummet in clay slip. The average weight of clay per cc. is calculated as follows: Cw= D(S‐d)/D‐d, where Cw, is average weight of clay per cc., D is the specific gravity of clip and D is the specific gravity of water. It is impractical to separate by elutriation, clay particles smaller than 0.003 mm. which constitute 50–100% of many clays. It is possible to classify particles as small as 0.0001 mm. by the plummet sedimentation method and the results are more uniform than those obtained by elutriation.
doi: 10.1111/j.1151-2916.1921.tb17313.xpmid: N/A
ABSTRACT After discussing the relation of draft to heat transfer and kiln dimensions the conclusion is reached that the higher the flame temperature in the kiln the more economical will be the firing operation, and that a combination of natural and mechanical draft makes an ideal installation.
Danielson, R. R.; Reinecker, H. P.
doi: 10.1111/j.1151-2916.1921.tb17314.xpmid: N/A
ABSTRACT The investigation deals with the development of some white enamels for copper watch dials, thermometer scale plates, and signs. The effect of varying Na2O, PbO, cryolite, SiO2 and B2O3 on the properties of the enamels was studied in twenty enamel compositions. The following conclusions were reached: (1) Correct melting is extremely important in the preparation of copper enamels; (a) Slow air cooling of the frit is preferable to quenching in water. (b) Repeated melting tends to promote opacity and to eliminate dissolved gases. (2) A somewhat reducing atmosphere during firing avoids oxidation of the copper. (3) Slight changes in enamel composition have a decided effect on the resultant properties. (4) Sodium oxide promotes gloss but reduces opacity very decidedly. (5) Lead oxide promotes fusibility without materially reducing opacity, except by dilution. (6) Cryolite is not a desirable flux or opacifier as it tends to develop a matt finish. (7) It is desirable to keep the boric oxide content low and good enamels may be produced without it. (8) By using “white arsenic” as an opacifier tin oxide is unnecessary. (9) The following were the best enamels obtained and these appear to be equal to a number of watch dial enamels examined: C‐19 and C‐20. 20. (10) A second group of compositions which appear to promote results equal to those in use for thermometer scales, advertising letters, etc., are C‐10. 10. C‐21, C‐22, and C‐24. In selecting these compositions, all factors such as opacity, gloss, texture, fit and resistance to attack of copper have been considered.
doi: 10.1111/j.1151-2916.1921.tb17315.xpmid: N/A
ABSTRACT A detailed description, with drawing, is given to show the use of oxy‐acetylene gas in a small furnace for using refractory cones. The advantages claimed, are (1) simplicity of construction, operation and repair; (2) ease of control; (3) high temperatures obtainable; (4) oxidizing atmosphere; (5) comfortable working conditions, owing to the small volume of hot combustion gases; and (6) portable character of the furnace, fuel and firing apparatus, permitting its use in localities where gas or electricity can not be obtained, such as in the field or at the mine. The following change is suggested in the Ceramic Society's specified rate of heating for cone fusion tests. “The rate of heating shall not exceed that corresponding to one‐half a cone (approximately 10 degrees C) per minute within a range of ten cones below that of the final fusion cone and this rate shall preferably be decreased to one cone per five minutes within two cones of the final cone of fusion.”
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