The publication of Theophrastus on Stones is without question an important event for scholars and students interested in the history of pure and applied science. By common consent one of the greatest of the Greek philosophers and naturalists, Theophrastus is still a highly significant figure in the development of mineralogy and other scientific and technological areas, yet no modern annotated translation of his treatise On Stones has hitherto been available. It has been more than two hundred years since the first English translation by John Hill appeared. French and German translations have been published within the last fifty years as parts of other works, but they contain neither text nor commentary. This book, which includes the original text, an English translation, and a commentary, gives the reader-with or without a knowledge of Greek-an invaluable interpretation of the technical aspects of the treatise and the rationale of the processes described in it. It will have a wide appeal not merely for the classical scholar but for a larger public whose interests lie in such scientific fields as chemistry, archaeology, mineralogy, and geology. Earle R. Caley and John F. C. Richards have brought to completion a book which is a distinguished addition to scientific and classical literature. Earle Radcliffe Caley, a native of Ohio, received the M.Sc. and Ph.D. degrees from Ohio State. From 1928 to 1942 he taught at Princeton University. On several occasions he served as a chemist for the excavation of the Agora at Athens, Greece. Since 1946 he has been on the faculty of Ohio State's Department of Chemistry. Professor Caley has written on various applications of chemistry to archaeology. For certain articles in this special field, he received the Lewis Prize of the American Philosophical Society in 1940 and a citation from the American Classical League in 1954. John Francis Chatterton Richards, author of various publications on classical literature, was graduated B.A. at Oxford in 1921 and M.A. in 1927. He began teaching at Dartmouth College in 1927. From 1930 to 1936 he was Instructor and Tutor at Harvard University, from which he received the A.M. and Ph.D. degrees. He has taught classics at the University of Rochester, and, since 1939, has been in the Department of Classics at Columbia University.