varian analytical instrument division

Innovations for chemists: HA-100 NMR

The high-resolut ion HA-100 Spectrometer is recognized as the NMR standard in labora­tories throughout the world. Its unmatched performance is now even better, with sensitivity in­creased to 40:1. With this new sensitivity, plus stability and re­solving power, the HA-100 meets and exceeds rated specif ica­tions year after year with only normal maintenance. This is an­other example of innovations in NMR, EPR, Mass Spectrometry, and Laboratory Magnets to help the chemist do a better job more easily. For information, contact your local Varian representative.

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as micro (<20 A), intermediate (20-200 Â) and macro (>200 A) leading to distinct types of sorption, and the book is organized along these lines.

Chapter 2 includes a long discussion of the BET and other monolayer meth­ods as applied to nonporous solids. Chapter 3 concerns surface area and pore size distribution from physical ad­sorption data on porous solids. The reader is left uncertain as to the best way to handle the hysteresis problem in calculation of pore size distribution.

Chapter 4 considers adsorption on microporous solids which is a timely and needed review in view of the cur­rent importance of molecular sieves. Chapter 5 deals with conversion of adsorption data to two dimensional equations of state by the Gibbs equa­tion and interpretation from this point of view including a discussion of Ross and Olivier's work with this approach. Chapter 6 on chemisorption, although not comprehensive, should be useful to workers in the field of catalysis.

The text is concluded by a useful section on experimental methods, numerous figures and tables serve as documentation and improve under­standing of the various relationships throughout.

The book is particularly recom­mended for workers in the adsorption field and should also be of value to those interested in determining surface properties of solids. I t provides an excellent, well organized, up to date review of British literature and limited reference to U. S. work.

In. general, it is similar to other re­views on the subject and does not ap­pear as critical as the objective implies.

Typography is excellent and no sig­nificant errors were noted. Author in­dexing is rather hard to utilize.

The Formation and Properties of Pre­cipitates. Alan G. Walton, xi + $32 pages. John Wiley & Sons, 605 Third Ave., New York, Ν. Y. 10016. 1967. $11.

Reviewed by Lester C. Howick, De­partment of Chemistry, University of Arkansas, Fayetteville, Ark. 72701.

In this book Professor Walton pre­sents a readable and current introduc­tion into the state of our knowledge concerning precipitate formation and properties. While providing a quanti­tative approach, he does not allow the presentation to become overly mathe­matical and constantly stresses the in­terpretation and meaning of the ex­pressions as well as commenting upon the presence or absence of experimental support for their acceptance.

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