ANALYTICAL CHEMISTRY
534
Vacuum Manipulation of Volatile Compounds. R. T. Sanderson. viii 162 pp. John Wiley & Sons, Inc., 440 Fourth hve., Iiew York 16, S . Y., 1948. Price, $3.
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The title of this book might convey to the casual observer an uncertainty or misconception as t o its contents. The subtitle, which states that it is “a laboratory manual describing the application of high vacuum technique in experimental chemistry,” is less ambiguous. The statement of the purpose of the text as set forth in the preface is far too modest. The claim that it is to provide information “to enable an investigator with an average background of scientific training and experience to construct and operate a SIR: The biuret method of Robinson and Hogden [ J . Biol. general purpose high vacuum apparatus for chemical research” Chem., 135, 707, 727 (1940)l for the determination of serum prois Fell fulfilled. But, in addition, it should prove to be a font teins is RTidely used for the determination of protein in tissue of information for most workers in the field of high vacuum. homogenates, enzyme preparations, and similar materials, alThe emphasis is on fundamentals. Certain sections are though details of such an adaptation have never appeared in the detailed and skillfully presented-for example, the chapter on literature. In dealing with such crude materials, an annoying the production and measurement of low temperatures. Howturbidity often appears in the final color solution, making visual ever, a similar discussion of high temperature is lacking. One measurement of the color difficult and photometric measurement might also question the wisdom of omitting some details on inaccurate. quartz, graded seals, glass-metal seals, and instrumental methods Because this difficulty seemed to occur most often in liver from available for measurements in high vacuum, though references starved or protein-depleted animals, the turbidity was considered are made to some of these The sections on vapor pressure and probably lipide in nature. It was found that the turbidity could fractionation are excellent. Safety in vacuum work is wisely be removed in the following manner: emphasized. A notable and very useful feature is the inclusion The color is developed in the usual way, including 10 minutes, in the index of an extensive table of the vapor pressures of pure standing a t room temperature. The tubes are then chilled on ice compounds. for 2 hours. This coagulates the fatty turbidity and permits its This book, then, fulfills the need for a compilation of the ready removal together with the excess copper hydroxide, by methods and equipment to be used in vacuum chemistry, and, filtration through a coarse filter paper (Schleicher and Schuell although not exhaustive, should be most useful as a handbook No. 410 is suggested). A certain amount of the color is absorbed on fundamentals. JOHN J . NAUGHTON by the paper, as pointed out by Robinson and Hogden, but it has been found here that if a standard curve (using rabbit serum standardized by Kjeldahl determinations) is prepared from a Bibliography on Water and Sewage Analysis. B. H . Weir, filtered series of standards, the curve follows Beer’s law as well as Poagie E. Murray, George W . Reid, and Robert S . Ingols. does a curve of centrifuged standards, although the slopes of the viii 215 pages. Special Report 28. State Engineering two curves are appreciably different. Experiment Station, Georgia Institute of Technology, Atlanta, ROBERT 5 . FEINSTEIN Ga., 1948. Price, $4.
Modification of Biuret Method of Protein Determination
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According to the authors, “This bibliography was prepared in a n effort to bring together an indexed guide of the pertinent literature on water and sewage analysis., .’, It appears that this effort has been successful. The bibliography, which is not annotated, contains 2560 references and is intended to be complete through January 1, 1948. Although most of the journals consulted are for the period 1920 to 1947, references from Chemical Abstracts date back as far as 1907. The great majority of references concern water analysis. An important feature is the listing of references to abstracts such as Chemical Abstracts, as well as to original papers. The bibliography includes an author index. The subject headings are divided into 36 convenient groups, beginning with acidity, alkalinity, and aluminum and ending with toxic gases, turbidity, and zinc. In addition to the consecutively numbered references throughout the book, there is a supple mental list of cross references to methods of analysis, such a biochemical, colorimetric, and volumetric. Every serious worker in the fields of water and sewage analysis will want to have this S.K. Love book for reference purposes.
University of Chicago Chicago, Ill.
p-Aminobenzoic Acid SIR: In Table I1 of the paper entitled “p-Aminobenzoic Acid and Its Sodium Salt” [AKAL.CHEM.,20, 919 (1949)] we reported various pH values for aqueous solutions of paminobenzoic acid with and without added equivalent amounts of sodium hydroxide. A footnote should have been added explaining that these pH values represented those of concentrated stock solutions used t o prepare the dilute solutions for spectrophotometric analysis. These values have been questioned by Vandenbelt and Doub ( 3 ) and t o clarify the situation further x-e have rechecked our results. We have determined that the pH of the final dilutions and changes should be made as follows: pH 3 . 5 9 t o 4.78 9.19 11.58
5,ll 5.49 5.82
6.86
Doub and Vandenbelt’s ( 1 ) observation of wave-length maxima a t 284 millimicrons for p-aminobenzoic acid in distilled water a t pK 3.75 is correct, However, in our studies we have attempted to demonstrate a method of spectrophotometric analysis for p The Division of Analytical and Micro Chemistry, AMERICAN aminobenzoic acid in distilled water without added buffers or acidifiers a t its wave-length maxima in the solvent. We have perCHEMICAL SOCIETY, has announced the personnel of its Paper formed these experiments many times and have consistently obCommittee: W. M. MacNevin, chairman, A. Q. Butler, J. R. tained wave-length maxima for p-aminobenzoic acid in distilled Churchill, Wm. G. Batt, G. T. Wernimont, Walter J. Murphy, water a t 266 millimicrons. and L. T. Hallett.
Analytical Division Paper Committee
