Technikatörténeti szemle 19. (1992)

KÖNYVISMERTETÉS - Papers of the First „MINERALKONTOR” International Conference on the History of Chemistry and Chemical Industry (Veszprém, 12-16 August, 1991)

Period II (the use of X-ray analysis) — starting from 1913 1 subperiod (transitional) 1913—1919 2 subperiod 1920 — the end of the 1960's 3 subperiod the beginning of the 1970's — mid 1980 4 subperiod started from the mid 1980's. In contrast to the most contemporary crystal chemists that connect the appearance of the science with the creation of the X-ray method, we refer the appearance of the science to the beginning of the 19th century. We'd like to remind that V. M. Goldsmidt (4) considered the first law of crystal chemistry the proposition of R. J. Hafiy that „to every chemically homogeneous compound corresponds a group of crystal forms typical particularly for the given compound." In other words, crystal chemistry of period I and modern crystal chemistry are drawn together by the search for the relation between the chemical composition and the crystal structure. Before 1913 only the external structure was spoken about, whereas in the following years the inner structure, i. e. the spatial arrangement of atoms in the crystal. We consider it expedient to separate four subperiods within the second period. The first subperiod is characterised by the search of the language, the accumulation of the necessary scope of structural data, the appearance of the first monograph the on the results of X-ray analysis of 33 compounds (8), and articles which generalized the results of the first deciphering (9-13). The year of 1920 is chosen as the boundary between two first subperiods because in this year a fundamental article by W. L. Bragg (14) was published, in which the first attempt to establish the regularities in the changes of interatomic spaces in a series of compounds with the same chemical formula was done. The necessity to differentiate between the second and the third subperiods is caused by „the revolution in X-ray analysis" that took place at the end of 1960's and the beginning of 1970's, i. e. massive usage of automatic diffractometers and computers, which allowed to increase for several orders the accuracy and the rate of the structure determination. The appearance of the fourth subperiod is determined by the fundamental importance of the cycle of researches on the determination of the distribution of the electron density in a crystal. It partiy changed the idea about the already studied structures and, mainly, greatly broadened the realm of contacts between crystal chemistry and quantum mechanics, which led to a more profound understanding of a chemical bond in a crystal. About the place of crystal chemistry in the system of sciences This question was discussed in publications listed in a chronological order (15—22). Their characteristics are given in article (3). By the way, the question on the status of modern crystal chemistry is more urgent. The lack of specialized research institutes and chairs under the conditions of an impetuous progress and considerable influence of crystal chemistry on the development of a whole complex of sciences is more a paradoxical than a difficult-to-explain fact.