Esw~tiallyall of the reviewer's fnvor~kswere found i n thc index. rlnrh i. cxcrllent and iz of nppru~mntely:Wll liner. A n r r amplr of thc detail of the text 1s the rreatmcnt of arrtoarerir ester, covering over 17 pages. I n the index under this topic are found the following headings: Acetoacetic ester, 185-202; acylation of, 197; alkylatian of, 1 9 3 4 ; enol-keto forms, 188-92; ketal, 196; ketone and acid hydrolysis, 192; preparation of, 186, 206; reactions of, 187, 193; structure, 186; tautomerism, 192, 194: theories of mechanism of formation. 197-201: use in svn;h&ir, 193,250,258,639. On the theoretical side relatively full treatment is given such topics as the coordinate bond, parachor, dipole moments, aromaticity, the fine structure of naphthalene, etc. In spite of the wealth of detail offered, if one attempts t o point out one or more tooics which might be covered more fully for a balanced treatmint, perhaps further discussion of the Perkins reaction and the side reactions occurring in the use of the Gtignard reagent might be desirable. A chapter is included on the literature of organic chemistry. This is a feature seldom found in introductory texts and yet most chemists will agree with the author's statement that "the importance of acquiring the habit of recourse to the varied and extensive literature of chemistry can scarcely be overemphasized." OSBORNE R. QWAYLE
DRYINGAND DEHYDEATION oa FOODS. Harry W. VMZLoesecke, Senior Chemist, U. S. Department of Agriculture, Washington, D. C. Reinhold Publishing Corporation, New York, 1943 302 pp. 64 figs. 82 tables. 15 X 23 cm. $4.25. This is a very useful book for those engaged in dehydration of foods for the military forces and Lend-Lease, as it contains much advice and information on equipment and processes. The author is well qualified by his recent research experiencein the U. S. D. A,. Western Re~ionalLaboratom. It is rather highly condensed and hence s&es better as anoperating manualihan as a textbook. In a fieldof technology that is undergoing suchrapid changesand progress as a result of current research and development by many agencies, i t is inevitable that soon after issue the book will lack some important data. Far example, the sulliting of vegetables for dehydration in order to protect them against harmful oxidative losses in flavor, color, and vitamins is now coming into prominence, but is not covered in this book. I n the chapter on types of dehydraters practical information precedes theory, and theory is covered rather bridy. I n most publications theory is presented first, but perhaps for the practical operator the author's sequence may be the better. The reviewer might mention a few points on which he differs from the author or that appear to him to be in error. The author states that floor kilns dry food slowly. As a matter of fact, those used for apples in the Pacific Northwest dry quite rapidly; e. g., requiring only 6 to 61/r hours to dry apples, which time compares very favorably with that in other dehydraters. Incidentally, most kilns for apples in California and Washington are equipped with fans to increase the rapidity of air circulation, a fact which the author does not stress. I n the drying of berries the author omits use of SOp to protect color and flavor; the reviewer finds such treatment very desirable. The impression is given that pears are dehydrated commercially in important amounts. I n so far as the reviewer is aware this is not the case, a t least in the West. The mooortion of the raisin crop that is dehydrated is not about 30pe;cent as indicated by theauthor, but normally is less than 15 per cent. The method for SOn assay on page 259 gives total SO1, not merely the free, if the reviewer understands the directions correctly.
I t is our belief that the directions for refreshins of dried weet a l k \hould I,? more specific; e. g , volurnc of vryetahle to volu m * of 1120fur refre.hin): would he rnorc u,cful than thr preient directions. Ilowrver, thi? ii a fault found in othcr publications also. I n the section on dehydrater types it is mentioned that 50 to 75 per cent of the air may usually be recirculated. This condition would be satisfactory for prunes, but not for rapidly drying products such as cabbage and apples where little t o no recirculation is advisable. The imrtial lid of patmls in the appendix i- urcfui, allhaugh it would be morc so if a fcw of the mom important patents had been hriefed or sumnlnrized, and if thc titles had been somewhat more descriptive. On the whole, the reviewer does not find that the errors are serious or numerous. On the contrary, he recommends the hook t o dehydrater operators and students of food technology as a most useful guide and source of information. The lists of references a t the ends of several chapters are valuable to those who wish t o refer t o the original source material or who wish details not presented in the book. w. V. CRWESS ~~~~~
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AND SYNTHETICS.MOW& D. ENCYCLOPEDIA 011 SUBSTITUTES Schongold, Editor. Philosophical Library. Inc., New York, 1943. 382 pp. 15 X 23 cm. $10.00. This encyclopedia hss the scope of a chemical dictionary for industry applied specifically to the field of synthetic resins, plastics, and substitutes. The trade names of the resins and plastics are up to date for the moment, and these substances are described as completely as can be expected for products covered by patents. The selection of organic and inorganic compounds covers the field chosen in an arbitrary fashion although the book is not cramped for space. The volume will be useful for the manufacturer since physical properties, solubilities in common solvents, and uses are described, and possible suhstitutes for wartime needs are given for many materials now difficult to obtain. This last is the hook's only important distinction from other cheaper and more comprehensive dictionaries now available. The reviewer found in cross references all the synonyms used, which is commendable. It contains an index of trade names with the companies which make them, and a short subject index. Condensed structural formulas for organic compounds could have been given without using more space. The few which are given lack clarity because the common methods of the organic textbook are not used uniformly and too large a percentage are incorrect, e. g., vanillin, formaldehyde, ethyleneglycal, lactic acid, and isopropyl ether. The naturally occurring and synthetic camphor formulas are written in different ways without showing the real distinction. Acrylonitrile is the only compound found by the reviewer containing a double bond which is so indicated. Antimony oxide (wrong formula) is distinguished from antimony trioxide without any given reason. Nitralim (misspelled) is printed twice and defined as two different chemicals on the same page. Chemists and Victory Gardeners will probably cast doubt on the reliability of the entire encyclopedia when they see the following astonishing statement credited to the Ministry of Agriculture in England, "common salt may be substituted for potash as a fertilizer." The price is inflationary. LEALLVN B. CLAW
BROWN UKIVBRUTY PPOMDENC*, RHODBISLAND
