ARTICLES 



THE ANALYSIS OF CRYSTAL-STRUCTURE 



BY X-RAYS 



By W. T. ASTBURY, B.A. 



University College, London 



It is now just over ten years since Laue first proposed the use 

 of crystalline structures for the investigation of the real nature 

 of X-rays. From Laue's hypothesis and the experiments of 

 Friedrich and Knipping which confirmed it have arisen two 

 parallel lines of research, one of w^hich still uses known crystal- 

 structures for the investigation of X-rays, while the other uses 

 well-defined X-rays as a means of arriving at the ultimate 

 significance of crystal-structure. The work of the Braggs 

 and their followers has, of late, been largely directed along the 

 second of these two main lines of research, and, if we ignore 

 the blank left by the war, it has been so fruitful of results 

 that it is now felt that we are rapidly passing into a stage of 

 development of the subject when principles will be evolved 

 that will not only correlate the facts of crystal-structure, but 

 also, at the same time, throw considerable light on the hidden 

 forces of the atom itself. When the science was new, crystal- 

 structure was studied for its own sake, but since then the out- 

 look has broadened considerably, and the elucidation of its 

 problems for the sake of physics and chemistry and science 

 in general is a subject that is growing apace. 



Probably the most important recent advance in the study 

 of crystal-structure has been the work of Sir W. H. Bragg on 

 the structure of organic crystals {Proc. Phys. Soc, vol. xxxiv, 

 December 1921). Apart from the purely physical and crystal- 

 lographic point of view, this work possesses a peculiar interest 

 for the chemist, insomuch as it emphasises and confirms the 

 structural formulae to which he has so long and confidently 

 pinned his faith. Hitherto the structural formulae of the organic 

 chemist have been merely the theoretical links in the powerful 

 chain which stretches from marsh-gas at one extreme to the 

 most complicated dyes at the other. But now the searching 

 analysis of crystals provided by the use of X-rays has shown 



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