to the clearness, especially to beginners and those not acquainted with technical terms and even prevent blunders among technical men themselves. As a suggestion to individuals who have developed their own courses independently of and before the advent of this work, the experience of the writer may serve as a way of introducing their students to the point of view of the bwk. We have not used the book as a text, but have recommended it as a personal reference passession. We have then assigned t o the individual students different chapters or sections in the book as "Reports from Our Consulting Chemical Engineers, Walker, Lewis and McAdams," whose technical details and mathematics we wish to have explained in detail for all of our "Works Staff." This problem requires the student to thoroughly study and digest the section assigned and gives him practice in reducing scientific and technical engineering material to the level of the ordinary business or fadory staff. The authors of this work have gone extensively into the theoretical basis of some of the chemical engineering operations. To some, this mathematical treatment will appear extreme, particularly when resort was inevitablv made to emoirical factors. The men in the industry should not expect too much of theoretical science or become discouraged when they find i t does not sound the depths which they are compelled to do from time to time when facing a concrete prohlem for which industry demands a solution. The authors have made a notable effort t o balance theory with their own actual engineering experience. I t does not take much of a prophet or much engineering experience to realize that the whole field of engineering is destined to more and more turn to chemical engineering for assistance. This text should therefore be a valuable work in the hands of evem civil, mechanical. electrical. or other engineer dealing with changes in materials whether chemical or physical.
First Report of the Committee on Photochemistry. H. S. TAYLOR,Chairmal~; W. D. BANCROXT, G. S. FORBES,H. G. DE LASZLO, S. C. LIND.LOUIS A. T m NER. Reprint and Circular Series of the National Research Council, Number 81. 95 pp. 17 X 24.5 cm. $1.00. Reprinted from J. Phys. Chem., 32, 481-575 (April, 1928). The papers included are: Introduction. H. S. Taylor. 1 p. Experimental Technique for Quantitative Study of Photochemical Reactions. George Shannon Forbes, 21 pp. Absorption Coefficients. Henry G. De Laszlo, 4 pp. The Excited Systems Formed by the Absorption of Light. Louis A. Turner, 9 pp. Quantum Processes in Photochemistry. Hugh S. Taylor, 13 pp. The Displacement of Equilibrium by Light. Wilder D. Bancraft, 44 pp. Relation hetween Photochemical a i d Ionization Reactions. S. C. Lind, 3 PP.
Wearing Apparel: Its Manufacture, Utility, Selection, and Care. seven radio talks. Radio No. 37. University of Pittsburgh, Pa., 1928. 62 22 an. 50 cents.
A series of Publication Pittsburgh, pp. 15 X
The titles of the talks included are as follows: 1. Cotton Fabrics. C. F. Goldthwait. 2. Undergarments. Edgar R. Clark. 3. Wool Clothing. Lloyd E. Jackson. 4. Silk H ~ I &E. I wassell. 5. Rayon Goods. George H. Johnson. 6. Furs. Lloyd E. Jackson. 7. H a t s . Rob Ray McGregor. The contents of this publication should he of especial value to persons who are desirous of acquiring an elementary knowledge of textiles. It should also be helpful to teachers of home economics and elementary chemistry.
arme en&.
Laboratory Manual of Colloid Chemistry. HAW N. HOLMBS..Second edition. John Wiley and Sons, New York, 1928. xviii 228 pp. 23 X 15 an. 8.00.
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