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COMMUNICATION TO THE EDITOR
(3) BURTON, E. F.,AND BISHOP,E.: J. Phys. Chem. U,701 (1920). (4) DEMARTINI,F. E.:J. Am. Water Works Aasoc. SO, 85 (1938). E., AND SORUM, C. H.: J. Phys. Chem. 44,62 (1940). (5) FISHER, (6) HATCH,G.B., AND RICE,0.: Ind. Eng. Chem. 81.51 (1939). (7) HATCH,G.B., AND RICE,0.: Ind. Eng. Chem. 91, 1572 (1940). (8) HAZEL,F.:J. Phya. Chem. 46, 731 (1941). (9) HAZEL,F.:J. Phys. Chem. 46, 738 (1941). (10) HAZEL,F.: J. Phya. Chem. 45, 747 (1941). (11) HAZEL,F.,AND AYRES,G. H.: J. Phys. Chem. I, 2930 (1931). (12) HAZEL,F., AND AYRES,G. H.: J. Phye. Chem. I, 3148 (1931). (13) HAZEL,F., AND SORUM, C. H.: J. Am. Chem. SOC.6% 49 (1931). (14) LANOELIER, W. F.:J. Am. Water Works Aeaoc. !U, 1500 (1936). (15) LARSON,T.E., AND BUSWELL,A. M.: Ind. Eng. Chem. 31, 132 (1940). (16)RICE,O.,AND PARTRIDQE, E. P.: Ind. Eng. Chem. 91, 58 (1939). (17)ROSENSTEIN, L.: U.s. patent 20,754(1938). (18)TRAX, EDW.C.: J. Am. Water Worka Assoc. 91. 1495 (1940). (19)WEISER,H.B.:Colloid Chemistry, p. 228. John Wiley and Sons, Inc., New York (1939). (20) WILLEY,A. R., AND HAZEL,F.: J. Phya. Chem. 41,699 (1937).
COMMUNICATION TO THE EDITOR LIQUID-VAF’OR COMPOSITION OF THE BOILING TERNARY SOLUTION ETHYL ALCOHOLGLYCEROLBENZENE
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Sir : I am much indebted to Dr. Hugh J. McDonald for discussing with me a number of points in his paper, “Liquid-vapor composition of the boiling ternary solution ethyl alcohol-glycerol-benzene,’’ published in the Journal of Physical Chemistry 46,706 (1941). However, the following comments should be noted: (I) In figure 1, the residue curves are plotted with moles of each component upwards and total moles of residue out to the right; a point representing the change of residue composition during distillation (for any one component) then move8 from the upper right corner towards the origin; the motion is opposite on the distillate curves. (2) On page 711,the statement is made that the “slope of the curve a t any point is, of course, the mole fraction of each constituent in the vapor a t that point.” This is confusing. For the distillate curves, with moles of component plotted against total moles, the ratio of ordinate to abscissa is, of course, the mole fraction in the total distillate. The value of the slope has an additional term, as may be shown by simple calculus. For the residue curves, the ratio of ordinate to abscissa gives the mole fraction in the residue (as is correctly stated in the paper) ; the slope of a residue curve gives the mole fraction of that component in the “instantaneous” vapor just leaving the residue, not the mole fraction in the total distillate. (3) The curve for benzene (or either other component) in figure 1 must be
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rotated 180°, not 90°, to make it coincide, as stated on page 712. This symmetry is, of course, due to the method of plotting the data. The curve for benzene is not drawn through the experimental points, but Dr. McDonald states that other runs showed this shape for the curve. (4) In figure 2 on page 712, the points for such a y-z curve may perhaps lie approximately on a straight line, but the slope of the line (for Sample 10) is approximately eight, and not unity, aa may be shown by calculations on data read from figure 1. This higher ratio of benzene in the vapor to benzene in the liquid is more plausible, considering its relative volatility in the system. Unfortunately, other y-z curves cannot be calculated from the information in the paper, although the determination of their slopes and thence the “distribution coefficients” would be of some interest. WORDENWARING. Richardson Chemical Laboratory, The Tulane University of Louisiana, New Orleans, Louisiana. Received December 20, 1941.
NEW BOOKS Ezperimental Physical Chemistry. By FARRINGTON DANIELS,J. HOWARD MATHEWS, AND 30” WARRENWILLIAMS. 6 x 9 in.; xvii 460 pp.; 121 fig. New York and London: McGraw-Hill Book Company, Inc., 1941. Price: $3.60. This book has undergone a thorough revision in going into the third edition, and in this process the authors have succeeded in considerably improving an already excellent text. AB the title implies, Ezperimental Physical Chemistry is not merely a laboratory manual of experiments in physical chemistry. I n addition to this i t is a handbook of the methods and apparatus of physical chemistry which will be a valuable guide to any one in research using the tools of this science. It is a book the usefulness of which to the student will only begin when he uses i t as a laboratory manual for his course in physical chemistry; he will find i t to be of increasing value in later years of research, An unusually large and wellselected list of references on every subject considered greatly enhances the usefulness of the book to one doing original work. The book is divided into three parts: laboratory experiments (300 pages), apparatus (108 pages), and miscellaneous operations (42 pages). The first part has been expanded in this edition, in part by increasing the number of experiments, and a180 by bringing methods and instruments formerly described in the second part into definite experimental procedures. The seventy-two experiments cover a wide range of topics, which are grouped in the following chapters: gases, liquids, opticochemical measurements, solutions, thermochemistry, colloid chemistry, homogeneous equilibrium, heterogeneous equilibrium, chemical kinetics, electrical conductance, electromotive force (tbere are ten experiments on this subject), electrode phenomena, dielectric constant, isotopes and exchange reactions, photochemistry. The second part of the book parallels the first in arrangement of subject matter. Alternative methods for various types of measurements are given, and most of the apparatus commonly used in physicochemical research is described. The third part covers calibration, thermostats, vsrious types of thermometric devices, elementary vacuur lube circuits,
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