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estimation of the num1)er of electrons involved in polarographic reductions. Hy ignoring such ditrerences between diffusion coefficients of different ions it is, e.g., wrongly concluded (page 73) that nitrate is polarographically reduced t o ammonia. The theoretical part gives more than an adequate background for the practical part. 1n.eighty pages a detailed discussion of polarographic equipment, performance of the determination of polarograms, and the interpretation of the latter for analytical purposes is given. A chapter of more than one hundred pages is devoted t o analytical procedures for the polarographic determination of inorganic and organic compounds alone and in various mixtures. This part could be made more complete. The chapter on the application of polarography t o the investigation of proteins and sulfhydryl-containing compounds is outstanding. This chapter should be of special interest t o physiologists, biochemists, and pathologists. The pioneer work carried out by Ileyrovsky’s school should stimulate further research in this important field of medicine. .The last chapter deals with polarographic titrations. On page 424 the author objects t o the use of the word “amperometric titrations,” which has been coined by the reviewer. Heyrovsky’s objection is based upon his statement that the use of a rotating platinum electrode as indicator electrode has no advantages. However, the rotating platinum elect rode has established itself in the last six gears as a very important electrode for the simple rapid determination of traces of quite a number of constituents. The last fifty pages give a complete chronological bibliography of polarography until 1041. .Such a bibliography is very convenient. In this country there is no need for such a bibliography, because a more up-to-date one has been prepared and is being distributed by E. I+. Margcnt Rr Company, Chicago, under the title Bibliography of Polarographic Literal w e , 1988-1945, IIeyrovsky’s book is a welcome addition t o the literature on polarography. I . R f . ROLTHOFF. Elastic and Creep Properties of I‘ilainentous Materials arid Other Hiyh Polymers. By HERBERT LEADERNAN.2 i 8 pp. (mimeographed). Washington. D. C.: Textile Foundation, 1944. This book is a highly theoretical treatment of the subject from the fundamental point of view of relating the properties of these materials t o their structure. The whole of P a r t I, comprising 103 pages, is devoted t o a theoretical and mathematical treatment of primary creep, the superposition principle, and the relation of mechanical mode!s and the structure of high polymers t o these properties. Part I,I is devoted t o the experimental work which Dr. Leaderman carried out as a Fellow of the Textile Foundation on the relationship of the elastic and creep properties of silk, viscose and acetate rayon, and nylon. These materials all show creep properties, i.e., their extension under constant load is not constant but is a function of time, the rate of creep decreasing with time. When the load is removed, elastic contraction takes place followed by a slower creep recovery. Although the latter ceases after a period of time equal t o that during which the load was applied-provided the load was below the yield point-a permanent set remains. Such a fibre is said to be“mechanicallyconditioned,”and this conditioning may be removed by treatment with water or steam followed h y drying without load. I n silk and the rayons the instantaneous or elastic deformation is proportional t o the load; however, the delayed deformation (creep) is not, but is a function of time. These materials do not follow the superposition principle. Sylon follows a still different set of laws. It exhibits both types of deformation but the reversible (elastic) deformation is a much larger proportion of the total. Two hundred ten literature references are included in this study, which is for experts in the field rather than laymen. I
