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agitation as a criterion of mixing intensity. However, they have not applied this concept to experimental results. The determination of the optimum design for producing a given degree and type of agitation is dependent upon a n experimental study of the variables of mixer design and location, vessel design, power consumption, and type and intensity of agitation produced. Because of the many variables involved in the design and in the conditions of use of agitators, it is very helpful when suitable correlations can be developed to permit the extension of the data beyond the condition of the actual tests. Just as in the study of turbulent flow in pipes, use of the principles of dimensional analysis is indicated. White and co-workers (8, 9) made a start along this approach and correlated power consumption with the variables of mixer design and operating conditions for the simple paddle stirrer. No attempt was made to correlate power consumption with intensity of agitation. Hixson and Wilkens (7), on the other hand, studied the effect of viscosity, stirrer speed, vessel dimensions, and baffles upon power consumption and agitation intensity for several types of stirrers. However, the effect of stirrer design was not completely investigated nor was a mathematical relationship of the variables worked out. Quantitative programs, such as those already started by White and Hixson, should be extended to cover all the more important types of mixing equipment. The experimental
AN ALCHEMIST
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technic involved should be based upon a standardized method of testing, and the results should be expressed in terms of an accepted index of agitation intensity. Such a procedure would permit the interchange of information between laboratories. The correlation of the variables involved on the basis of dimensional analysis should then lead to a more rational design and utilization of mixing equipment.
Literature Cited ( 1 ) Dodd, J . Phys. Chern., 31, 1761 (1927). (2) Esselen, motion pictures shown at meeting of Am. Inst. Chem. Engrs., Nov. 12, 1936. (3) Heller, 2. physik. Chem., A142, 4 3 1 (1929). (4) Hixson and Crowell, IND. ENG. CHEM.,23, 923, 1002, 1160 (1931). (5) Hixson and Luedeke, Ibid., 29, 927 (1937).
(6) Hixson and Tenney, Trans. Am. Inst. Chem. Engrs., 31, 113 (1935). (7) Hixson and Wilkens, IND. ENQ.CHEM.,25, 1196 (1933).
(8) White and Brenner, Trans. Am. Inst. Chem. Engrs., 30, 585 (1934). (9) White, Brenner, Phillips, and Morrison, Ibid., 30,570 (1934). (10) White and Sumerford, Chem. & Met. Eng., 43,370 (1936). (11) White and Sumerford, IND. ENQ.CHEM.,25, 1025 (1933). (12) Ibid., 26,8 2 (1934). (13) White, Sumerford, Bryant, and Lukens, Ibid., 24, 1160 (1932). (14) Wood, Whittemore, and Badger, Chem. & Met. Eng., 27, 1176 (1922).
RECEIVED February 15, 1938.
Once again we are able to demonstrate the truth of that trite saying that “there’s nothing new under the sun.” At the Chemical Industries Exposition in New York in December last, the Kewaunee Manufacturing Company exhibited four exceedingly fine wood carvings of some of our alchemical reproductions. They also had their woodcarver a t work with chisel and carving tools, producing a fifth picture in wood. No. 89 in the Berolzheimer series of Alchemical and Historical Reproductions presents a photograph of a carved wood panel a t Abington Abbey, Northamptonshire, England. This carving shows a linen-panelled chair of the commencement of the Sixteenth Century. It will be noted that the Alchemist is a monk, that he is wearing heavy gloves, and t h a t apparently he is prepared to stir some brew or molten metal in the cauldron at his left. The purpose of the cap on the post of the chair is puzzling. D. D. Berolzheimer 50 East 41st Street, New York, N. Y.
A list of Reproductions Nos. 1 to 60 appeared in our issue of January, 1936, page 129: the list of Nos. 61 t o 72 appeared in our issue of January, 1937, page 74; Nos. 73 to 84 are listed in January, 1938, page 70, where also is shown N o 85. No. 86 a pears .on page 145, February issue, Nd. 87 on page 269, Larch issue, and No. 88 on page 427, April issue.
