THE STRUCTURE OF CHRYSTALS

Nelson Evening Mail, Volume LVI, 30 December 1924, Page 2

THE STRUCTURE OF CHRYSTALS

A notable advance in methods & studying the ’ structure of, nVatter ' was: achieved when ' X-ray's were used to analyse the composition of crystals. The greatest authority on this subject, Sir William Bragg, described; the progress and the dirdctionj of the research in ihis presidential address to the section" of mathematical aiid physical science at •the Toronto meeting of ’the';.Bri,tish Associa'ticlj'i;yHlf stafed'etliat, whereas the classification ; apcoydipg to, external symmetry divided' into 32 classes, investigation bv X-rays .lik'd demonstrated _230 pio-des, of intcrioj- arrangement. Tliis is advancing a .whole sta^e : to\yard -.the- final solution of, the structure problem,’.’ said Sir William Byagg. “We carry'the, aiialy.sjs right tip to the limits which ”can,' be •‘foreseen by the ipatliematical investigation of the geometry of space. We require only a sufficient number of'X-ray measurements'; if these can be obtained, the crystal then—with certain additional information as to polarity--ca'n be assigned to its particular anode or space, group, with • one or two exceptions. It .may lie that the structure of the crystals is so simple that, having got so far, the full solution, is already in sight. In the vast majbrity of;eases this is not so; 1 we have only come to the. cud of the second stage 1 of the work. Having solved, wholly or in great part, the structure o/ some, of the simpler crystals, and being able to proceed in all cases, even of the most, complicated: crystals, to the .deter- 1 munition of 'the number, of molecules in the cell, and of ■■■their mode of arrangement, we must try to currelate what wo have found with Ailie properties of the crystal. By that means we shall become gradually more certain of (lie general connection between the structure and its physical and chemical properties; we shall become aide to settle further structural details in various cases, and so, by alternate and mutually supporting advances, we may hope to reach our goal. . . . Wo. hope in the end to determine the position of every., atom, apd explain its influence through its nature and position upon the properties of the substance. Jt is the .eneipistiy of the spUd tlialj c,bines into Anew, 'richer in its variety ' even than t|ie chemistry we have studied for the past century, and possessing an importance wlhieli is obvious to: us all. Every side of scientific activity takes part in tin's advance, for all sciences are. concerned with the behaviour of matter.”