one. The experiments on cyanides, proteins and carbohydrates are more numerous than is usual in elementary manuals. A commendable feature of the ethyl acetate experiment is the inclusion of the comnositions and hoiline- ooints of constant-boiline mix. turcs of &I acetate, alcohol,nnd water. This will euplak, and bell, to avoid, a difficulty often encountered by students. 'l'he usrfulne.* or nppropriatcnes.; of a few erpcrimcnts may perhaps be questioned, e. g , three methods for making methane; the test for formaldehyde in milk; the preparation of formic acid from ovalic acid; two procedures for the preparation of thiocarhanilide; the preparation of phenyl isothiocyanate and triphenylguanidine; the henzilic acid rearrangement; the purification of benzene; the preparation of phenylmethylpyrazolone; the preparation of iodohenzene dicbloride. The procedures are in general clearly described. The object of each exercise, if it is not made ahvious in the heading, is stated briefly a t the outset. Several chapters are introduced by reaction charts which indicate the transformations t o be effected. Many experiments include interpolated questions (to be answered in the notebook) designed to induce the student t o think. The apparatus required will present no problems. The less simple outfits are shown by line drawings. The use of a heated funnel for filtration of hot solutions prior t o crystallization is not mentioned. There are a few places in which the directions appear to he insufficiently explicit. Thus it is stated that melting-point tubes should he "about 1.5 mm. in diameter," and that the melting point is the "temperature a t which the substance begins to melt." I n the test for halogen in presence of nitrogen and/or sulfur "a portion of the filtrate is acidified with nitric acid and boiled," directions which some students may follow faithfully (if not intelligently) and still get a fallacious test for halide. The distinction between methyl and ethyl alcohols, based on the formation of the salicylates, one of which "may he identified by its odor." seems t o need some clarification. The directions for the preparation of tribromophenal do not mention the formation of tribromaphenoxybramide nor provide for its reduction. The Schotten-Baumann reaction is so presented that a student taking the short course may conclude that this named procedure is limited to preparation of henzoic esters by use of benzoyl chloride. The authors have not been consistently careful with respect t o the inclusion and the strategic placing of directions for avoidance of fire and other hazards. The first explicit information as to a safe pmedure for recrystallization from volatile and in!Jammable solvents is given following the preparation of m-dinitrobenzene, a n exercise which is omitted from the short course and is normally reached in the long carmse only in the forty-second period. Crvstallizations fram inflammable solvents are directed in a number of a r l i e r cxperimcnrs (mcluding thkfirst experiment in the manual), in one case with a parenthetical caution, but irr no case with a crass refcmnce to the uplicit dirccrium in the later section. The experiment on the preparation of methyl cyanide fmm acetamide (twenty-third period) includes a caution with respect t o burns from phosphorus pentoxide, which information is withheld in several earlier experiments in which phosphorus pentoxide is used, uiz.,in the preparation of ethylene (optional exneriment for the fourth neriod) and in drvine ether for the Grienard reaction (fifteenth period). The student is directed to keep his anhydrous ether over sodium metal, but is given no suggestion as to a safe procedure for the eventual disposal of the residual sodium, though this operation involves probably the most serious single fire hazard in the student laboratory. The poisonous and irritating properties of phenylhydrszine are mentioned in the experiment on osszones, but are overlooked in the directions for the orenamtion of nhenvlhvdrazine footional about seventeen , periods later), involving isolation of the base by extraction in ether. A degree of caution which seems excessive appears in the experiment on ether, where the impression is created that the preparation of ether is hazardous and is advisedly done as a demonstration by an instructor. In the opinion of the reviewer the student should perform this experiment as a valuable lesson in the control and cobrdination of experimental conditions. The fire hazard should he no greater than in ether extractions, crystalliza-
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tions from imlammahle solvents, and disposal of sodium residues. The section on qualitative organic analysis suggests several steps in the preliminary attack (ignition test, determination of physical constants, elementary analysis, determination of the solubility group, and test for acidic or basic character using "universal" indicator paper), but the selection of the further procedures is left t o the student, who has already done some experiments (in the preparative course) on separations and on preparation of derivatives. The "unknowns" are selected from a lint of one hundred thirty-one compounds, representing most of the classes studied. Many of these compounds will have been encountered previously in the course and should he easy to identify. The comnounds are tabulated first in annroximatelv the order in . which they appear in the organic text, with the soiubility group indicated for each compound, and then in the order of ascending melting points of solids and of ascending boiling points of liquids. "No attempt is made to present a 'fool-proof' scheme of analysis which will make mental effort and alertness unnecessary. It is expected that students will make mistakes hut that they will learn as they proceed." The index lists principal topics and compounds made or studied. I t is brief, and does not consistently include processes, apparatus, and reagents. The omissions are probably unimportant in a hook of this type. The text is not as free of typographical errors as would he expected in a third edition, though the number and the character of the ermrs are not such as t o mar the book. One misspelling by no means peculiar t o these authors involves the name Tollens. There are no less than twelve appearances of its possessive form as "Tollen's." The reviewer is not well enough acmainted with oreviaus edtrions of thc manual to estimate the amount of rcvision represrnrrd by the third edition. The changes mmtionrd in its prcface include the omission of some eypcrlmcnts of doubtful value and the substitution of several "improved preparations," many changes in detail in the text, and expansion of the section a n qualitative analysis. The book has many merits, can unquestionably he made to serve as the essential guide for a thorough elementary laboratory course, and has enjoyed a deserved success. The book is bound uniformly with Dr. Williams' textbwk, and is printed on r%ther soft paper:. The publishers' admonition (following page xiii) t o the student to keep the manual in his reference library may he applauded in principle but is perhaps not altogether ingenuous. The reasons advanced are not wholly valid in the case of a n elementary laboratory manual (which is not a "textbook" and which has not been "studied from cover to cover") but if the notice helps to curb the traffic in second-hand lahoratorv manuals fa result oossiblv not unforseen bv the nubI~ihers)it will a190 aid teochcrs of organic cbcmistry, in whose cuurscs the scnsonal renppearnnces of used manuals, frcely and often inaccurately annotated by previous owners, constitute a deterrent to accurate work, careful observation, and cerebral activity. E. C. U'Aomn
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U N l V B B S I N OP PIINNSYLVAN,* P " , L A ~ ~ L F PBNNSYLV*NI* ~,*.
LABORATORY UNITS IN CHEMISTRY.William McPhcrson and Ed Henderson, Ohio State University, and George Winegar Fouler, School of Education, Syracuse University, and Supervisor of Science, City Schools, 329 pp. Ginn and Company, New York City, 1938. xii 68 figs. 17.5 X 23 cm. 5.80.
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LABORATORY UNITSIN CHEMISTRY is a laboratory manual and study guide for high-school chemistry. The manual is especially designed to accompany the book, CHEM~STRY AT WORK,hut may be used with other texts. The book contains fourteen units, the nature and purposeof which can be best portrayed by giving some description of the divisions within each unit. Each of these units is composed of t h e following sections: Question Survey. Study Outline, Optional Work. Unit Readings. Problems. Helps
for Optional Work, and Organization of the Unit in Question Form. Before discussing these topics briefly it may be helpful t o quote a few sentences from the preface of the manual which will state some of the beliefs and aims of the authors. "Mastery of subject matter, growth in knowledge of how t o study, and training in self directed work and in initiative are large factors in the learning process, for which definite provision is made in LABORATORY UNITSIN CHEMISTRY. . Teachers of chemistry recognize three major problems: (1) how t o relate the laboratory work t o the study of the text: (2) how to adapt the material of their science and the work in the classroom t o the individuals in a group; and (3) how t o test the important 'outcomes' of teaching. To help in solving these problems successfully the authors have brought together in LABORATORY UNITS IN C n e m s ~ n Ya combination of laboratory experiments and directed study activities, as a complement of CHEMISTRY AT Won5." The "Question Survey" of each unit consists of a series of questions which may be answered during the study of some of the experimental work, which the student may sometimes answer out of his general knowledge, or which he may be expected t o answer on the basis of a combination of reading, general observation, and study of the material in the unit before him. I n general, these questions are very goal and if answered carefully would represent an understanding of the material a t hand. The "Study Outline" of each unit is composed of various "Topics" and "Directed Study" for the topics. Some of these topics would require some experimenting and a good deal of outside study on the part of the student and should result in the acquiring of a large amount of information. Some would require knowledge based on observations a t home, in shops, factories, and elsewhere in addition to that obtainable from bwks. The section in each unit on "Optional Work" indudes a series of questions which are headed, "Do you believe?" At the close of each unit the student will find a series of Helpful Suggestioni for the study of material which is intended t o bring him to a condusion in regard t o his belief on the question before him. A few of these questions selected a t random from various units may help t o make this part of the unit clear. A few of them Nn, "Do you believe
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(a) That Seheele was the first person actually to see a gaseous element? (b) That golden hair can be made through chemistry? (To try to find an answer to this the student is told t o bleach hair with hydrogen peroxide, and so forth.) (c) That Moseley's discovery of atomic numbers was greater than Lavoisier's discovery of the cause of fire? (d) That bromides and iodides are salts-?' Many of the questions included in this"0ptiond Work' 'seem to the reviewer to he much less valuable than they might be. Or, a t least, it seems to the writer that the heading. "Do you believe" is a less helpful approach than some other might be. The section of each unit entitled "Unit Readings" contains an excellent and fulllist of readings taken from awide range of books and journals which the student should find interesting and helpful. Next in each unit comes the section headed "Problems." Thrw arc cornposed of the directions and reporr sheets fur the exprrirnrntal work of each unit. These erperimrnts follow rather rlowly the clarrical experimrnts for a high-school text with a somewhat larger number of the type that may be classed as experiments in organic chemistry, household, or every-day chemistw than is customarv in many texts. A number of them emphasize practical applications of chemical principles. These pages contain many blank spaces for the report on the experiment and the answering of questions. Immediately after each experiment, which is called a problem, there is a section called "Self Test" for the problem. This work is intended t o test the student's ability to think scientifically. I n this section a problem. a fact discovered by experiment, is stated. Following the statement of the problem is a series of statements containing the correct answer to the problem. The student is expected to find and check this correct answer. Another series of statements includes among correct and incorrect statements the reason for the
correct answer. The student also finds and checks the c m e c t one of these. This completes his test of his own ability t o "think scientifically." I n other words, the method used in this part of the unit t o test the student's ability to think scientilically is the reading of statements prepared by some one else and the checkine of the one that seems to fit the case. He does not have to formulate any questions himself, visualize reasons and words of his own "making," or express his thought in a statement of his own. He merely runs over statements of another and checks two of them. The reviewer wonders about the consequences of giving the students the impression that "scientific thinking" is as easy as this. The last material in each unit is called "Organization of the Unit in Question Form." This consists of a series of questions t o be answered as "true" or "false" or auestions with blanks to he filled in with a word or two. These &e intended t o help the student summarile the points brought out in the experiments of each unit. The manual, LABORATORY UNITSIN CHEMISTRY, nmtains an abundance of material to meet the needs of the most rigid highschool course. The book is quite free from actual errors, hut is much less free from the loose usage of words. It seems t o the reviewer that this careless use of words is not far from actual error and is particulnrly unfwtunate in a book intended for the studcnt just beginning to acquire a sriernifw vocabulary. lo vicw of the fact char the modern intrvretation of the structure of the atom is presented and used in a number of questions one is surprised to find oxidation referred t o as a gain of oxygen and reduction as the reverse of this. And, one can hardly excuse even one such error as the following: Hydrochloric acid is used for the preparation of chlorine "because the hydrogen of the acid may he removed by oxidizing it to water, leaving the chlorine in a free state." Aside from the rather prevalent loose usage of words. perhaps the most adverse criticism the reviewer might pass is one on the order of presentation of material which does not seem very consistent with the purpose of developing the reasoning ability of the student. For instance, the nonmetals, the chemistry of which is more difficult than that of the metals. are studied before the metals, thus making the work on non-metals more largely memory work than necessary. I t is diffieult, too, t o understand what the authors expect by way of equation writing because one finds, for instance, the simple equation for the reaction between silver nitrate and hydrochloric acid in water solution written out in detail with the names aboveeach compound pages after the student has been asked t o write the equation for the preparation of hydrogen peroxide and after he has been expected to "explain the bleaching action of chlorine." Although this manual seems less good in-many respects than the classical hooks of McPhersan and Henderson i t is a manual which is, by no means. too easy and is one that will interest many of those looking for something rather new in high-school lahoratory outlines for chemistry. But one who knows the former highschool bwks of the above authors will feel that this is not a wholly worthy attempt t o "modernize" the older hooks. And one hopes that a revision of LABORATORY UNITSIN CHEWISTRY will result in a mare careful use of terms and in some rearrangement of material which will lift more of the work above the level of a memory basis. H. H. FILLmGEn ~
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A SYSTEM OF CHEMICAL ANALYSISI1(IR THE COMMON ELEMENTS. Ernest H. Swift, Ph.D., Associate Professor of Analytical Chemistry, California Institute of Technology. Prentice-Hall Iuc., New York City. 1939. xxi 589 pp. 15 X 23 cm. $4.25. This addition t o the well-known series of text and reference works of the Preutiw-Hall Chemistry Series edited by Wendell M. Latimer is the result of ten years of development and practical investigation of the serviceability of "an analytical system which would provide not only reliable and sensitive qualitative informa-
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