BOOK REVIEWS. 495
This latter process has supplanted all the others in respect to its industrial importance.
Following a brief chapter on the history of nitrogen fixation processes which, in addition to the two just mentioned, includes the cyanamide and alkali cyanide methods as well, further preliminary information is furnished in the chapter on physical methods of studying chemically active states of gases and of investigating catalyst surfaces. Complementary to the articles on the "Arc Method of Nitrogen Fixation" and" Synthetic Ammonia" are valuable data on some physical properties of hydrogen, nitrogen, methane, ammonia, carbon monoxide and carbon dioxide and their mixtures. Coincident with this last chapter is another of equal importance on high pressure equipment and technic.
Leaving behind the briefer chapters covering the cyanamide, alkali cyanide and synthesis of urea methods, we again come to one of relative great importance, that on the oxidation of ammonia. In the production of nitrates, ammonia oxidation is as an essential a step as the synthesis of the ammonia itself. Considerable quantities of research have been accorded this oxidative process and much valuable information and data are furnished in the chapter.
Very appropriately, a chapter on synthetic nitrogenous fertilizers has been included. Some idea as to its extent may be had by realizing that a fertilizer may contain one or more of the calcium, potassium, sodium or ammonium salts of carbonates, phosphates, nitrates, sulfates and even chlorides, not to mention a number of simple and complex organic nitrogen compounds. What a large number of problems are involved in preparing combinations that will not cake or absorb moisture excessively; will be suitable for a particular soll or crop; will be economically sound in its application. The photograph of the interior of a spray tower, p. 453, is a classic in its field.
To top off these five hundred pages of fixed information and data, an extensive series of nitrogen statistics is appended. Glancing over these tables it was interesting to see that there now exists in Germany a synthetic ammonia plant capable of fixing 600,000 net tons of nitrogen per year. Following the statistics comes an equally imposing bibliography containing seven hundred seventy-eight references.
Fixed Nitrogen is well and interestingly written. The subject has been treated with a high degree of completeness at the same time presented in a clear and simple manner. The book should prove a handy reference to the instructor, the student, the industrial chemist as well as a treatise of general interest to others.
T. K. CLEVELAND. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS: Report No. 416, The N. A. C. A. Variable-Density Wind Tunnel, by Eastman N. Jacobs and Ira H. Abbott, 12 pages, illustrations, 23 X 29 ems.
Washington, Superintendent of Documents, 1932. Price five cents. This report describes the redesigned variable-density wind tunnel of the National Advisory Committee for Aerguautics; it supersedes a previous report that described the original tunnel. The operation of the balance and the method of testing are explained and the method of correcting and presenting airfoil data is described. A summary of the formulas for predicting the characteristics of finite wings from the airfoil section data as they are usually presented is also given.