HIS REVIEW PRESCSTS a general T view of the field of X-ray diffraction. This includes not only the strictly classical analytical applications of Xray diffraction, that is, qualitative identification of compounds and quantitative determination of a species, but also the use of X-ray diffraction to determine molecular and crystal structure, particle size, crystallinity, stacking faults, isomorphous substitution, phase transitions, polymorphism, etc. This review covers the period of January, 1968 through December, 1969, mainly by the appearance of an abstract during this time, although several journals were independently scanned. The literature of X-ray diffraction is extremely large. One can almoit open Chemical Abstracts to a page a t random and find reference in an abstract to the use of X-ray diffraction. A comprehensive review aould be a formidable task and of cource be not a t all desirable as the glut of material would obscure the purpope of a review, that ip, to indicate the directions in which the field is going. This review is not comprehensive; however, it is hoped that no works of new and fundamental significance have been omitted.I t is appropriate that we start this review by mentioning the paper and short book by Lawrence Bragg (29, YO) which appeared at the end of 1967. This is a historical review of the discovery of X-rays and their application as an analytical tool. There has been a rather large number of new books dealing with all aspects of X-ray diffraction which have appeared during the past two years. The very large (1000 page) "Handbook of X-Rays: for Diffraction, Emission, Absorption, and Microscopy," edited by Kaebler (log), should prove a useful source book to those whcse interests in X-rays are not strictly that of diffraction. Another general book which has appeared is volume 1 in the progresb in analytical chemistry series; "X-Ray and Electron Methods of .halysis," edited by Van Olphen and Parrish (245). Two volumes of that excellent series "Advances in X-Ray Analysis," which reports the proceedings of annual conferences on Application of X-Ray Analysis held in Denver, Colorado, have appeared during the past two years; volume 11, edited by Newkirk, Xlallett, and Pfeiffer (170), and volunie 12, edited by Barrett, Newkirk, and Mallett (20). Other books which have appeared deal with more specific applications of X-ray diffraction and will be mentioned in those sections of the review discussing these areas.
INSTRUMENTATIONResearch into the design of diffractometers is continuing, although a t first glance it might appear that there is no point to looking into basically different diffractometer designs as commercial diffractometers are quite excellent with regards to intensity, resolving powers and ease of usage. Parrish and Mack (181, 182) have reported on their construction of a diffractometer based on Seemann-Bohlin focusing geometry. The advantages of this system are that simultaneous focusing of all reflections make it possible to employ several detectors, and the stationary specimen ...
