]Mnir. 
Phil. Trans., A, vol. 198 , Plate i. 
Fig. A—-V" Steel as supplied, x 150 F. 
(Etched with IFNO 3 .) 
Fig. B 
Steel annealed for a few minutes 
at 750“ C. X 150 I). 
(Etched with HNO 3 .) 
Fig. C — 1" Steel as supplied. x 150 1). 
(Stained with Cocoa.) 
Fig. 1—Lovvmoor Iron as supplied. x 100 I). 
(Etched with IFNO 3 .) 
Fig. 2—Lowuioor Iron annealed for G liours 
at 750“ C. X 100 II. 
(Etched with HNO 3 .) 
