VOL.7, NO. 6
RECENTBOOKS
will be used chiefly by upper classmen and graduate students, the bibliography is altogether inadequate. Moreover, the book comes far short of being brought down t o date in certain cases. For example, the section on the precipitation of colloids mixht years . have been written twentv . . ago. There are errors, both typographical and otherwise, which should be eliminated from the next edition. B. WEISER HARRY
Colloid Chemistq: Principles and AppliMSc., cations. JEROME ALEXANDER, consulting chemist and chemical engineer. D. Van Nostrand Co., Inc., 270 pp. 1929. Third edition. x 15 X 23 cm. $3.00.
+
The first chapter starts out as an introductory one but has a paragraph on wave mechanics, apparently because a material corpuscle is involved. The second chapter starts with material units and includes a table of isotopes, the diameter of the galaxy. Sorensen's pH, and residual affinities. The reviewer finds i t difficult to believe, p. 25, that the decreased efficiency of enzymes, after the temperature exceeds a certain value, is due t o the average molecular velodty reaching so high a value that the enzyme cannot cope with it. Chapter I11 deals with the classification of colloids but does not include the iuterlacing systems t o which many jellies belong. Chapter IV discusses the consequences of subdivision, the most important of which is that the total surface increases. Chapter V gives an elementary and much simplified description of the ultramicroscope. I n Chapter VI we find the general properties of colloids. The remaining eight chapters deal with practical applications of colloid chemistry, the special topics being: astronomy; meteorology; smokes, fogs, and dusts; perfumes; geology; mineralogy; gems; agriculture; clays; ceramics and refractories; flotation; dyeing; shower-proofing
1449
fabrics; nitrocellulose and its products; celluloid; explosives; paints, pigments, varnishes; emulsions; soaps; lubrication; colloidal fuel; petroleum; asphalt; fire foam; insecticides; filtration; sewage disposal; photography; brewing; tanning; paper; tubber; foods and their preparation; baking; milk; ice cream; confectionery; gelatin and glue; glasses; metals and alloys; the time factor; iron and steel; steel; stepped transformation in steel; standard heat treatment terms; tin - lead alloys; zinc - copper alloys; bronzes: amorphous vs. colloidal theory; electrodeposition of aietals; boiler scale; cement, mortar, and plaster; chemical analysis; pharmacy and therapeutics; antiseptics and bacteriology; biology and medicine; enzymes; cytology; growth; evolution; physiology and pathology; capillary circulation; psychiatry; . a m phylaxis and immunity; healing of wounds; digestion; absorption, secretion, excretion; diagnosis; chemotherapy and colloid therapy; serum therapy; plants: bio-electric currents; some physicachemical aspects of life; mutation and evolution. C . This is hlghly impressive on paper but there is not much leeway when one tries t o treat some ninety topics in 158 mediumsized pages. I t is a hopeless task, for instance, t o treat ceramics, p. 109, in two short paragraphs. When so much has t o be left out, it seems a pity t o include anything that is wrong; but the color of the ruby is due t o dissolved chromic oxide and not to dispersed ferric oxide, p. 97. One wonders whether the author knows what the Cottrell process is, p. 89. When one says high-tension current, one d m not ordinarily mean direct current. The book is entertaining reading and should be read for that purpose only. WILDERD. BANCKOFT CDRNBLLUNIVERSITY
ITAACA, NBW YORK
Bacterial Metabolism. MARJORYSTEP~ENSON, M.A., associate of Newnham College. Cambridge, member of the scientific staff of the Medical Research
