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photography. The author introduces and uses throughout this section the vector density concept for expressing color and the color matrix and method of matrix algebra t o obtain quantitative criteria for color reproduction. The book is written as a text and should serve very well as such for a group of students who are acquainted with elementary physics and algebra and have a speaking acquaintance with chemistry. A set of seventy well-chosen problems with answers should increase the usefulness of the book. I t should prove interesting and useful t o amateur and professional photographers of more than average inquisitiveness and of considerably more than average technical background. The book is attractively printed on good paper and is well illustrated, including several excellent color plates. I t is very well and carefully written. A table of definitions of symbols might have been included for the convenience of the casual reader. The author and printers should be complimented on the practically complete absence of the usual trivial type of errors. LLOYDB. THOMAS.
Discovery of the Elements. 5th edition, revised and enlarged. By MARYELVIRAWEEKS. 578 pp.; 347 illustrations. Easton, Pennsylvania: Mack Printing Company, 1945. Price: $4.00. Each successive edition of this admirable history of the discovery of the elements brings a new wealth of material. Miss Weeks is not content with stating bare facts, dates, and methods. She has truly sensed the importance of giving the entire scientific and biographical setting of each discovery. I n her portrayal of this background she displays a n eager enthusiasm t h a t captures and holds the reader's interest. This edition seizes the opportunity of describing the discovery of some of the new transuranium elements. Part of this account will be subject t o revision i n the light of further evidence which was not available at the time of writing and all of which is not yet available. Incidentally, a fine point of judgment may be involved i n how far to go i n describing the discovery of new isotopes of previously known elements. Every chemist is indebted t o Miss Weeks for her painstaking work, and most chemists will want t o add this volume to their libraries. The discovery of a new element always has a degree of importance and glamor not attaching t o new compounds, although we now know t h a t i n a sense the elements are compounds of only three components, two of which were not known fifty years ago. 9. C. L I N D .
Toward Improving Ph.D. Programs. By ERNESTV . HOLLIS. 204 pp. Prepared for the Commission on Teacher Education. Washington, D. C.: American Council on '
Education, 1945. Price: $2.50. The science of physical chemistry is so deeply interwoven with graduate research and graduate degrees t h a t there is a n obvious interest and propriety in considering recommendations toward improving the Ph.D. programs. The author begins with a brief historical review of the development of Ph.D. degrees in the United States apd its relation t o the German and English systems of higher education. The influence of the American Association of Universities, of the American Association of University Professors, of the Association of Land Grant Colleges and Universities, and of the Association of State Universities is traced i n the development of several of the earlier graduate schools i n the United States. The failure of independent graduate institutions divorced from undergraduate work has led naturally t o the system of graduate courses superimposed on and t o some evtent in instruction and faculty overlapping with undergraduate courses as they exist today in America. A large part of the book is devoted t o statistical tables and their analysis, covering some twenty-two thousand doctorates conferred by institutions i n the United States between 1930 and 1940 and broken down into the principal geographical regions of the country.
