80 



By etching with HF we get figures somewhat deviating 

 from the preceding ones. 



(Fig. 24) The form is as shown in the figure, but always 

 rather indistinct and not sharply bounded. 



/■{041} is rather highly corroded; the form resembles a 

 grain of barley with the point turned downward towards the 

 edge formed with ô{010}- 



(021, ^ (Fig.2o) The figur- 



es vary somewhat in 

 breadth by the use of 

 different acids. 



e{02l) generally 



Fig.25. Etching figures on {041} shows comparatively 



produced by acids. few figures. 



(111) 



(111) 



(101) 



(0*1) 



Fig. 26. Etching figures 

 on {021} produced by acids. 



Fig. 27. Etching figures 

 on {111} produced by acids. 



(Fig. 26} The form is always lengthened and truncate up- 

 ward, and pointed downward, towards the edge formed with 



f{m). 



o{lll} is rather slightly corroded; the figures are quite 

 unsymmetrical. 



(Fig. 27) By the use of strong and concentrated acids more 

 rectilinear figures like oblique squares are also produced here. 



