MAY 15, 1939
ANALYTICAL EDITION
observed in tests with blended coals 51A and 51B. The high maximum fluidity value shown by the blends, 51B, 50B, 51A, and 50A, in comparison with those of the constituent coals of these blends, is a property in harmony with the wellknown fact that many properties exhibited by blends are not a mean of the same properties shown by the constituent coals in the blend. Often a blend exhibits a particular property, or properties, to a greater degree than either constituent coal. This is well illustrated by the maximum fluidity values of coals 51A and 50A.
Summary and Conclusions A modified Gieseler plastometer and test procedure have been developed. Plasticity data obtained by this method are compared with data found by the Agde-Damm dilatometer and Davis plastometer methods. Considering the differences in operating characteristics of the three instruments, good agreement is shown on typical temperature points and on degrees of fluidity. The modified Gieseler plastometer method has the advantages of covering both the preplastic and plastic temperature ranges, of measuring the small degree of fluidity shown by low-volatile bituminous coals, and of indicating the relative fluidity between coals. This relative fluidity reaches a maximum in high-volatile A bituminous coals of about average volatilematter content. The excellent agreement between the initial softening temperatures determined by the AgdeDamm and Gieseler test methods substantiates the generally accepted explanation that the “initial contraction temperature” (Agde-Damm) indicates the beginning of a gradual softening of the coal particles. The Gieseler test shows that such softening does take place. The characteristic temperature points in the plastic temperature range determined by the three test methods measure particular stages of the fusion of the coal and its solidification into semicoke. Except where the operating characteristics of the three instruments necessarily indicate certain differences due t o the mode of measurement, a good order of agreement between data obtained by the three test methods
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is shown. Alleged arguments against the imperfections of any one method largely disappear when one considers the proper limitations to which this method must be confined in actual use.
Acknowledgments The authors desire to express their sincere thanks to J. D. Davis for many helpful suggestions during the course of the work. Grateful acknowledgments are made to H. M. Cooper, under whose direction were made the coal analyses shown in Table I, and to G. C. Sprunk and H. J. O’Donnell for their petrographic analyses of coals 52 and 54. Literature Cited (1) Am. Soc. Testing Materials, Proc. Am. SOC.Testing Materials, Pt. I, Vol. 36, pp. 812-18, 1936 (A. S. A. M20.1-1936; A. S. T. M. D388-36T). (2) Auvil, H. S., and Davis, J. D., U. S. Bur. Mines, Rept. Investigations 3403 (1938). (3) Brewer, R. E., and Atkinson, R. G., IND.ENQ.CHEM.,Anal. Ed., 8, 443-9 (1936). (4) Davies, R. G., and Mott, R. A., Fuel, 12, 371-82 (1933). (5) Davis, J. D., IND. ENG.CHEM.,,4nal. Ed., 3, 43-5 (1931). (6) Davis, J. D., Jung, F. W., Juettner, B., and Wallace D. A., IND.ENQ. CHEM.,25, 1269-74 (1933); Carnegie Inst. Technol. and U. S. Bur. Mines, Coop. Bull. 60 (1933). (7) Fieldner, A. C., and Davis, J. D., “Gas-, Coke-, and ByproductMaking Properties of American Coals and Their Determination”, U.S. Bur. Mines, Monograph 5, pp. 106-9 (1934). (8) Fieldner, A. C., Davis, J. D., Thiessen, R., Kester, E. B., and Selvig, W. A., U. 9. Bur. Mines, Bull. 344, 14-19 (1931). (9) Gieseler, K., Gliiclcauf, 70, 178-83 (1934). (10) Jung, G., Gl.itclcauf, 71, 1141-8 (1935). (11) Pieters, H. A. J., and Koopmans, H., Het Gas, 53, 539-45 (1933); see also Pieters, H. A. J., Koopmans, H., and Hovers, J. W. T., Fuel, 13, 82-6 (1934). (12) Pieters, H. A. J., Koopmans, H., and Hovers, J., Cong. intern. mines met. geol. appl., 7th Session, Paris, 1935, Mines Sect., Vol. 11,496-506; Rev. ind. min6rale, 376, 880-90 (1936). (13) Union for Supervision of Power Economy of Ruhr Mining Co. a t Essen (Report for 1931-1932), Gliiclcauf, 68, 737 (1932). PUBLISHED by permission of the Director, Bureau of Mines, U. 5. Department of the Interior (not subject t o oopyright).
A Simple Vibrator JOSEPH F. VINCENT AND MORTON M. SPRUIELL Ohio State University, Columbus, Ohio
W
HEN gases are being passed through an absorption train, i t is frequently difficult to maintain a uniform flow of gas through the system. This difficulty may be easily overcome if by some means the absorption tubes are caused to vibrate gently. A simple and inexpensive type of vibrator suitable for this purpose is illustrated in the diagram. An ordinary laboratory stirrer, A , having an L-foot, is rigidly attached to the cross bar, C, which is common to the absorption tubes. The absorption tubes, D, are mounted on the cross bar by means of buret clamps, B. The cross bar in turn is rigidly fixed to the standards by means of the double clamps, F. On the L-foot of the stirrer there is a short piece of gum rubber tubing, E , extending beyond the glass. The stirrer is slanted a t such an angle that when rotated E strikes the lower end of the last tube. The vibration thus established is carried through the cross bar, C, to the rest of the tubes in the train. More efficient operation is obtained if the tubes, D , are mounted near their tops and if the cross bar is attached near
the top of the standards. It may be necessary to apply mineral oil to the rubber foot, E, for proper operation. Use of this easily made vibrator leads to a flow of small gas bubbles through the absorption train.
