Oxford: At the Clarendon Press 1925. First Edition. 31 pages. Original light grey wrappers printed with green titles. 8vo. Untrimmed as issued. Soiling to the covers, minor chipping to the edges as normal. 8 figures on 2 pages. Crease to rear wrapper, short closed tear. Frontispiece is a photomechanical print of a Laue Photograph of Basic Berrylium Acetate. Very Good. Wraps. 
This small pamphlet does an excellent job of describing in laymen's terms the "Crystalline State" (or solid state) of matter (versus gaseous or liquid states). Bragg was a very good teacher, and this comes through here. It also brings into focus the importance of X-Rays in determining the structure of the Crystalline State at this point in time, contrasting what could be done previously and now in simple, understandable terms. Bragg also talks about specific examples which chemists had theorized, and how the new technology could confirm their conjectures and observations. Ever wanted to know why graphite is such a good lubricant? You can learn that here.
The Braggs (father and son) were awarded the Nobel Prize for Physics in 1915 'for their services in the analysis of crystal structure by means of X-rays'. Their experiments showed that X-rays could help identify the atomic structure of materials. 'the work of Bragg and his son Lawrence in 1913-1914 founded a new branch of science of the greatest importance and significance, the analysis of crystal structure by means of X-rays. If the fundamental discovery of the wave aspect of X-rays, as evidenced by their diffraction in crystals, was due to von Laue and his collaborators, it is equally true that the use of X-rays as an instrument for the systematic revelation of the way in which crystals are built was entirely due to the Braggs. This was recognized by the award of the Nobel Prize jointly to father and son in 1915.' (from the Nobel Prize Biography of WH Bragg).
"George John Romanes established a fund in 1891 for an annual lecture on any subject, approved by the Vice-Chancellor, relating to science, art or literature." (Bodleian Library catalog)