BOOK REVIEWS

graduate students and non-experts" and emphasises the transition metal hydrides. A knowledge of chemical thermodynamics rtnd structural chemistry is assumed by the author.

The author has criticdly reviewed the available literature and has selected typi- cal systems to illustrate basic principles. The subject matter is well organized and the book is written in a simple and concise style.

Suocessive chapters present: a classi- fication of metal hydrides based on chemi- cal bonding principles, preparations1 meth- ods and characteristic properties, crystal structure and phase relationships, thermo- dynamics of metal hydrides, electrical and magnetic properties, and non-staiehi- ometry and lattice defects.

On the basis of concentration de- pendence of the relative partial molal enthalpies of solution the author intro- duces the concept of a solid solution of hydrogen in a non-stoiehiometric hydride. This concept seems rather academic a t the present state of our knowledge of hydride structures.

The results presented in the chapter on electrical and magnetic properties appear inconclusive. I n the words of the author, the last two chapters of this hook may become obsolete in a. few years.

The treatment of solid state chemistry of binary metal hydrides in this mono- graph is hampered by our poor under- standing of the nature of the chemical

bond a t the present time. Reliable quantitative relationships are difficult to obtain despite the practical importance of metal hydrides in modern technology of materials.

The book gives a fairly accurate ac- count of the state of the art of binary metal hydrides. It may well serve to stimulate mare research in this field.

ALFRED PEELER Westinghouse Research

and Development Center Pitlsbwgh, Penmyluania

Ernrt Mach: Wegbereiter der Modernen Phyrik

K. D. Heller, Haifs. Springer-Verlag, Genna. New York, 1964. vii + 169 pp. 1 portrait. 23 X 15 cm.

Perhaps the nicest gesture of recognition of outstanding merit in the field of physical science is the longstanding custom of naming fundamental units after the person most prominent in their discovery, development, etc. In this day of super- sonic jets and missiles the man on the street or even those working with such fast moving objects hss no or little ides of why speeds are measured in mitchs. The word comes from the name of the Austrian

approaches the speed of sound and the Mach number represents the ratio of the

speed of a. body to the speed of sound in undisturbed sir.

This book (in German) carries the suh- title, "Forerunner of the LModern Physics!' Mach's life was not dramatic and little space is therefore devoted to his career that was spent in universities st Prague and Vienna. Most of the text is made up of excerpts from his books and his voluminous correspondence. Among the subjects treated are mechanics, mnsations, heat eta., dong with the philosophical and psychological aspects of the field of physics. His writings influenced the sub- sequent developments in all three fields. He did not accept. the theory of atoms until late in his career and his critique of Newtonian mechanics influenced Ein- stein, though Mach was not convinced of the validity of the relativity theory.

Dealing as i t does with topics outside the chemical field it is certain that the l m k nil1 not a p p : t l I( , !!..t!,y Amn!.t~, ttur will ( ~ l y i r i z t . 1x1 yvwrk. 1.e 1 1 1 1 1 x 1 ~ c d I)). what i t I.!$S !<, ~ T c I . 'IL) mhcr. 11 :iii r d , :i glimpse into the thinking of a gifted man whose merits are being more appreciated as these sciences (also psychology and philosophy of science) grow more mature.

RALPH E. OESPER Unitrersily of Cincinnati

Cineinnali. Ohio

A474 / Journal of Chemical Education