PLATE II 



Fig. 1. Diagrammatic representation of the method used in 

 obtaining X-ray diagrams of fibrous material. The beam is 

 coUimated by a cylindrical slit, s, 0-5 mm. diameter, made of some 

 material impervious to X-rays, such as lead. The fibre bundle F is 

 placed up against one end of the slit and perpendicular to the beam. 

 The diff"racted rays are received on a photographic plate and are 

 recorded there as arcs. The diagram shown here is that of ramie 

 fibres. In all subsequent X-ray diagrams in this book the cell 

 length lies, as here, parallel to the longer edge of the page. 





Fig. 3. X-ray diagram of hemp fibres before and after de- 

 lignification. A mask of brass was placed over the 

 photographic film in such a way that only two opposite 

 quadrants in a circular aperture were exposed at one time. 

 The two specimens (treated and untreated) were therefore 

 photographed on one film and therefore processed together. 

 This reduces to zero any complications due to variation in 

 development technique, etc. 



Upper right ami lower left: Untreated hemp fibres. 



Upper left and lower right: Fibres after lignin extraction. 



[Facing p. 42 



