of molecular attraction is not at all understood." Another desirable improvement is the omission of many of the purely empirical equations, such as Prud'homme's equation connecting absolute boiling point, melting point, and critical temperature of liquids; Arrhenius' equation representing the viscosity of a liquid as a function of the temperature; and the empirical ionization equations for strong electrolytes. An empirical equation, based as it is upon limited data, is often little more than a lucky guess, and may have no relation to the mechanism of the process. It usually contains a number of constants which must be determined for each substance or reaction, and is thus limited in its applicability. The reviewer is mindful of the fact that a purely empirical equation is better than none a t all for calculating unknown quantities and that even our most important equations contain specific constants. However, in the teaching of physical chemistry, the emphasis needs to be placed upon those well-established principles and equations which have been repeatedly verified and whose correctness is generally recognized. From the mechanical standpoint the bookrepresents an improvement over previous editions. The book manifests the same superior quality of workmanship which has consistently characterized the International Chemical Series. Readers will welcome the elimination of troublesome diagonals in the printing of mathematical formulas. Cuts have been reduced in size, and derivations of formulas, formerly in fwtuotes, moved up into the body of the text. The b w k is strikingly free from typographical errors, only one coming to the reviewer's attention, nanlely, Poiseuille, which on page 100 is rendered "Poiseville." A certain inconsistency in the use of chemical terms is apparent in numerous places. For example, an pp. 84 and 157. both "benzene" and "benzol" are used. On oaee . - 162. the author uses thc accepted term "diphenyl" hut on pp. 350-1. "hiphrnyl"and "bibenzyl." Although chemical terminology islargrly arbitrary. it is desirable that i t be runsirrent and uniform throughout the
Onc must recop-nizr that the revision of such a book, involving as i t docs the elimination of less important matrrinl, a critical iclcct~on,digestim and assemhlv of ncw knowledge, and thc correction of previous errors, is a t best a prodigious task. In the present instance, the author deserves commendation for the success he has achieved. As a means of imoartinz a thoroueh fundon~cntalknowledge of the subject, thc hook deserves wide ndoptjon as s tcxl in the first course in physiral chemisry.
Tna Tnsnnroc~EMIsTRY OF THE CHEMICALSSWSTANCES.F. Russell Bichowsky, Editor for Thermochemistry for the Internotional Criliull Tables, and Frederick D. Rossini, Scientist in Physical Chemistry a t the National Bureau of Standards. Reinhald Publishing Corporation, New York City. 1936. 460 pp. 15 X 23 cm. $7.00. The scope and plan of organization of this useful compilation are best indicated by quotations from the preface. "There are four main sections to the present book: (I), theintroduction or explanatory part; ( 2 ) ,the table of h a t s of formation, which is the fruit of the work; ( 3 ) ,the text,inwhich the original published data are cited and discussed; and (4), the List of references to the literature, which includes references to all the published data bearing on thermochemistry." "The table of values contains a list of all the chemical substances (except carbon compounds containing more than 2 carbon atoms), for which there are thermochemical data, together with valuesfor the heatsof formation (orheat of transition, fusion, or vaporization) of each substan&. I t was deemed ex;edient not to include in the present table values for the heats of formation of carbon compounds containing more than two carbon atoms. It should be possible t o obtain from this table. by simple addition and subtraction, the heat of any process involving any of the substances given, with an accuracy as great as is actually known. There are listed in the table 5840 values of
heats of formation, and, in addition, 350 values of heats of transition, fusion, vaporization, or reaction, for substances far which no values are given for the heat of formation." "In thelist of references are given the citations t o theliterature for d l the published works bearing on thermochemistry which are discussed or mentioned in the text. This list of 3730 references includes all the publications covered by Chemical Abstracts up to January 1,1931, and nearly all of the important and significant contributions which have been published in the period from January 1. 1931, to January 1. 1934." "The standard temperature selected for the values given in this book is 18" Centigrade, following the procedure of the thermochemistry section (Bichowsky) of the International Critical Tabla. The authors have been reluctant not to use the almost universally accepted standard temperature of 25' Centigrade for thermodynamic calculations; but the selection of la9 as the standard temperature is practically necessary in this c a x because all of the monumental work of Julius Thomsen and of Marcellin Berthelot was done a t or near 18" and there are not now n\;ulal,lc sufivirnr hrar capacity data with which to make accurate convrr&n to 25' (thii is especially important for reaction%inrulving substances in aqncous solution where the temperature coefficient is usually very large). I n later years, as the data on heat capacities become available, or as the heats of many of the reactions, which have until the present time been measured only by Thomsen or Berthelot or both, are redetermined, it will be quite feasible to use 25' as the standard temperature." One mav oerhaos . hooe that in a future edition the cornoilers and publishers will sre fit to inrludc 23' values, wen though it bc impo4hle to ronvcrt the entire compilation to this self-consistent basis. 01-10 R s r ~ m
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SEMI-MICRO QUALITATIVEANALYSIS. Carl J. Engeldn, Professor of Analytical Chemistry, University of Pittsburgh, Tobias H. Dunkelberger, University of Pittsburgh, and William J. Schiller, Mount Mercy College, Pittsburgh. John Wiley & Sons, Inc., New York City, 1936. x $- 265 pp. 14.5 X 23 cm. $2.75. The text "Semi-Micro Qualitative Analysis" represents an innovation in the teaching of the subject of qualitative analysis t o beginning students. I t introduces new ideas which, without doubt, are a great improvement over the usual macro methods and procedures. It is a great pleasure to learn that these semimicro methods have now been made available to students engaged in a study of the subject of qualitative analysis for the first time. The project is to be highly recommended; it is a desirable as well as a distinctive contribution to the teachingef chemistry. The advantages of dealing with dropi'or a t the most 1-2 cc. of solution are auite evident. Considerable time is saved the student in carrvine out filtrations.. washiner. evaoorations. and ~, , "~ handling of apparatus and so1utiun.i. Precipitation of the sulfides by hydroxen sulfide is facilitated and, in addition, since relatively small amounts of the gas are required for the procedures, it does not become a serious problem in the contamination of the atmosphere of the laboratory. Dealing with small quantities of materials imparts t o the student the necessity of exercising care in his manipulations and, above all, naturally leads to neatness. Another major advantage is the saving made in the expense required to provide for laboratory work. Large amounts of chemicals and large pieces of apparatus are no longer indispensable. The procedures described by the authers are not intended to be of the "micro" type. They appear to have reached the condusion through experience that procedures intermediate between the usual "macro" and the real "micro" schemes are the most suitable for the beginning student. I n this way the principles of ionic equilibria and the chemistry of the more common positive and negative ions are preserved. Group precipitations and separations are camed out in accordance with the usual macro schemes, with the exception that the amount of solution or material to be analyzed is reduced to a practicable minimum. ~~
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