NEW BOOKS
Automatic Control of Chemical and Petroleum Processes. Theodore J. Williams and Verlin A. Lauher. 336 pages. Gulf Publishing Co., Book Division, 3301 Buffalo Dr., Houston 1, Texas. $10.50. This hardback book not only covers the basic principles of automatic con trols in detail, but also discusses con trols from the practical viewpoint of the user. Problems which can be found in everyday plant situations are used as examples. Representative chapters are written on such topics as the use of the Bode diagram for control system study, the Nyquist diagram and how it is used, and the place and use of the root locus. Methods
in
Enzymology.
Vol.
V.
Edited by Sidney P. Colowick and Nathan O. Kaplan, xxv + 1087 pages. Academic Press Inc., Ill Fifth Ave., New York 3, Ν. Υ. 1962. $28.00. This volume in the series is intended as a supplement to Volume I of this treatise and to Section I of Volume II. These earlier volumes dealt with the preparation and assay of enzymes. Volume V contains some general pro cedures for purifying enzymes and for preparing biological specimens for en zyme studies. However, for the most part, it consists of new procedures for the study of newly-found enzymes or for carrying out newly-developed tech niques. High Temperature Microscopy in Base Metal and Light Metal Re search. Wm. J. Hacker & Co., Inc., P.O. Box 646, West Caldwell, N. J. This 16 mm. sound film is available on a loan basis. Automatic
and
Remote
Control.
Edited by J. F. Coales and coedited by J. R. Ragazzini and A. T. Fuller. 4 volumes. Butterworth Inc., 7235 Wisconsin Ave., N. W., Washington 14, D. C. 4 volumes, $165.00; single volume, $44.00. This book contains the proceedings of the First International Congress of the International Federation of Auto matic Control (IFAC) held in Moscow in 1960. The papers were presented by an international group of experts in the field including approximately 100 American authorities and 129 from the U.S.S.R., all of whose papers are fully translated. The work is divided into four vol umes. Volumes I and I I deal with the
Cary Spectrophotometers measure reliably at high absorbances where effects of many sources of error are minimized Many materials such as high density filters, solutions which cannot be diluted, etc., must be measured at high absorbance. In many instances, such a technique should be chosen because of important advantages it offers; it reduces errors which affect the zero line such as those caused by contamination of cell windows, slight shifts in cell positions, etc.; it makes possible fewer dilutions and allows use of more accurate, convenient and inexpensive longer path cells. Cary spectrophotometers provide several advantages for high absorb ance measurements. The low stray light of their double monochromators allows accurate, direct readings for most problems. Their high light gathering power, stable and sensitive photometers, and intense sources give good relative freedom from random noise limitations. Both the Model 11 and Model 14 spectrophotometers are capable of directly measuring absorbance values up to 2 or more; with reference beam attenuation they can accurately measure absorbances of 4 or more over most of their ranges. For measurements of this type, special neutral density screens are avail able for use as convenient and reproducible beam attenuators. (These screens are also valuable as precise secondary standards of absorbance for verification of photometric reproducibility. ) In addition to making high absorbance measurements, Cary spectrophotometers offer unique benefits for a wide variety of problems. INSTRUMENTS For information, write for data file A 18-52.
Cary
APPLIED PHYSICS CORPORATION . 2724 So. Peck Rd., Monrovia, Calif. Circle No. 20 on Readers' Service Card
VOL. 34, NO. 6, MAY 1962
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