SURFACE LAYERS OF CRYSTALS 



140 



1 



180 CARB. 



303 V2 EMERY — ► 



nA = 2d SIN e 



X-RAY 

 TUBE 



Fig. 10.— Section of transmission Lane camera. Si and S . are coUimating slits 



/ 



Fig. 11. -Transmission Laue ,)hotographs of a 4 mm.-thick BT quartz plate, (a) I-ace 

 nearer film laiiped with 180 carborundum. Other face iai'-ped with 303. emcr>-. (b) 

 Same as a, after 47 hours' etching, (c) Same as a, but through a ditlerent part ol the 

 plate. Plate rotated 180° in its own plane, (d) Same as c. alter >0 mmutes ctchmg. 



