INDUSTRIAL A N D ENGINEERING CHE.MISTR Y
February, 1926
stand how much they owed him, but personally I count it a great privilege to have been associated with him for many years as a student and member of his faculty, and to have thus caught some of his high ideals and enthusiasm for accurate and pains-
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taking work. The School of Chemistry and the fine building it now occupies are, in a sense, monuments to his efforts, but his best reward must lie, as for all great teachers, in the love and gratitude of the men he taught and inspired. FRANCIS C. FRARY -
NOTES AND CORRESPONDENCE Present Status of the Facts and Theories of Detonation Editor of Industrial and Engineering Chemistry: The article under this title by G. L. Clark and W. C. Thee [THIS JOURNAL,17, 1219 (1925)] interested me greatly as a critical review of the subject as found in recent literature. The recent work of Bone on combustion a t high pressures, the original theory of “detonation control by inert gas diluent,” originally adyanced by Ricardo, and the later work of Alcock are about the only recent important phases not mentioned. This subject is so complicated by conflicting, unclassified facts and theories that i t is an extremely difficult subject to review adequately in one paper without “treading on some one’s toes,” unless the conflicting evidence is first further coordinated and classified. Among some of the assertions made by Clark and Thee with which I cannot agree is the statement found in the second paragraph, second column on page 1223 : Woodbury, Lewis, and Canby, firing acetylene-air mixtures, state that increased temperature produced little effect upon the rate of flame propagation. With this Brown, Leslie, and Hunn seem to agree. The paper “Gaseous Explosions. I-Initial Temperature and Rate of Rise of Pressure” [THISJOURNAL,17, 397 (1925)] presented complete experimental and theoretical evidence t h a t initial temperature (not ignition temperature) has t i pronounced effect upon the rate of rise of pressure, flame propagation, and detonation in all homogeneous reactions. I cannot understand how any one could read this paper, the abstract, or even its title, and conclude t h a t we believe “increased temperature produced little effect upon the rate of flame propagation.” GEO. GRANGER BROWN UNIVERSITY OF MICHIGAN ANN ARBOR, MICH. December 12, 1925
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Editor of Industrial and Engineering Chemistry: The writers of the paper on the “Present Status of the Facts and Theories of Detonation” greatly regret that the first two sentences of the second paragraph, second column, page 1223, have suffered in the process of condensation of the paper, and lead t o a mistaken interpretation of the work of Woodbury, Lewis, and Canby, and of Brown, Leslie, and Hunn. The word “such” should be inserted before “effect” in the first sentence, in order t o refer back to the assertion by Mallard in the preceding sentence that increase in initial temperature increases speed of propagation, rate of combustion, rate of rise of pressure, etc. Following the word propagation should be inserted, “but that increases in temperature above a certain definite value are actually accompanied by a decrease in the rate of combustion.” These omissions were overlooked in the final form of the paper, probably because of confusion between ignition temperature and initial temperature. We shall appreciate publication of these corrections. I n the opinion of the writers, however, the drivers of automo-
biles who know that detonation occurs much more rapidly with hot engines on hot days will seek t o find explanation of the apparent discrepancy between practical operation and these experimental results. The interpretation, of course, hangs upon very careful definitions and distinction between rates of reaction and rates of rise of pressure, etc. GEORGEL. CLARK MASSACHUSETTS INSTITUTE OF TECHNOLOGY CAMBRIDGE, MASS. December 29, 1925
Note on “Influence of Reaction Rate on Operating Conditions in Contact Sulfuric Acid Manufacture” The authors wish t o call attention to the fact, t h a t the differential equation for reaction rate employed throughout this article [THISJOURNAL,17, 593 (1925)l is in units different from those ordinarily used. Furthermore, in the equation as written the change in volume of the reacting gaseous mixture is neglected in so far as i t affects the differential coefficient itself. To make the equation exact the right-hand side should be multiplied by the volume. The reaction constants as computed, while proportional t o the constants expressed in absolute units, are also functions of the total pressure and temperature. For constant pressure conversion the equations given need no modification unless the pressure is other than atmospheric or the change in total mols of the reacting dixture is considerable. W. K. LEWIS E. D. RISS
Preparation of an Ash-Free Wood Charcoal In the recent note by the author, THISJOURNAL,17, 1114 (1925), he unintentionally neglected to mention that Max Latshaw first prepared the charcoal under the author’s direction. This method became routine in the author’s laboratory when wood charcoal was needed, and as such the note was written. L. H. REYERSON
Calendar of Meetings American Ceramic Society-Atlanta, Ga., February 8 to 13, 1926. American Chemical Society-71st Meeting, Tulsa, Okla., April 5 to 9, 1926. American Electrochemical Society-Chicago Beach Ho eel, Chicago, Ill., April 22 to 24, 1926. Association of Chemical Equipment Manufacturers-2nd Chemical Equipment Exposition, Cleveland, Ohio, May 10 to 15, 1926. American Institute of Chemical Engineers-Berlin, N. H., June 21 to 23, 1926. Fourth Annual Colloid Symposium-Massachusetts Institute of Technology, Cambridge, Mass., June 23 to 25, 1926. The diagram of the apparatus accompanying the article entitled “Use of Methyl Salicylate in a Flowmeter,” by R. H. K. Foster, THISJOURNAL, 18, 82 (1926), should be inverted.
