NEW BOOKS P. HORWOOD.15 x 23 cm.; The Sanitation of Public Water Supplies. By MURRAY 181 pp. Baltimore: Charles C. Thomas, 1932. In the first chapter, dealing with public health activity, the author divides the history of development of the field into successive periods in which the sanitary engineer, the bacteriologist, and the physiologist exercised a dominant influence. He regards the control of environment as principally responsible for advances made -an opinion which will not be shared by many public health workers. A more extended discussion of vital statistics would be a welcome addition t o this chapter. In chapters I 1 and I11 the development of public water supplies is treated historically and statistically; information concerning several large cities is cited. Chapter IV discusses the requirements of drinking water, dealing with physical, mineral, and bacteriological standards. The relation of water and disease is comprehensively treated in chapter V, particular attention being given to typhoid fever. Methods of water treatment are detailed in chapters VI t o X, inclusive, titled successively: “The Purification and Improvement of Water Supplies,” “Water Softening,” “Slow Sand Filtration,” “Rapid Sand Filtration,” and “Disinfection.” The chapters on “Softening” and “Rapid Sand Filtration” are exceptionally good, typical chemical reactions and descriptions of operating conditions characterizing the discussion. Disinfection by use of hypochlorite, chlorine, and chloramine, with discussion of the chemical “mechanism” is treated in the final chapter, with methods of use for various conditions. The use of ultra-violet light is also described. The material in this book covers the title comprehensively in a n elementary manner, and it should be of value to the general reader, although each technical reader perhaps would prefer to arrange and emphasize the material differently while agreeing t h a t its selection is substantially satisfactory. F R E D E RBASS. ~C
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131 pp. LonRHODES. 19 x 13 cm.; x Phase Rule Studies. By J. E. WYNFIELD don: Oxford University Press, 1933. Price: $2.25. In the introduction E. L. Rhead says: “Owing to its many practical applications a knowledge of the Phase Rule has become indispensable in the equipment of the modern chemist. . . . The Phase Rule is capable of application in many directions, not only to subjects that are palpably chemical in their nature, but to others that are not essentially so, or, a t qny rate, are not usually approached from a chemical standpoint. The principles of the Phase Rule are eminently applicable in geology, mineralogy, and metallurgy, although the introduction is generally by avenues other than a course in pure Chemistry.” The chapters are entitled: introductory; one-component systems; two-component systems in which mixed crystals are not formed; two-component systems in which mixed crystals are formed; three-component systems, isothermal diagrams; threecomponent systems, the polythermal model and its projections; miscellaneous applications of the phase rule; systems of four or more components and their graphical representation; experimental methods employed in phase rule work. 557
