Phil. Mag. Ser. 6, Vol. 8, Pl. IX. 
Fig. 15.—Speculum metal, polished across Fic. 16.—The same, surface film completely 
emery ridges and furrows. Normal formed. Normal light. x 775. 
light. X 775. 
Fic. 17.—The same, surface film removed Fre. 18.—The same, surface film restored. 
by etching. Normallight. x 775. Normal light. x 775. 
Fig. 19.—Lead, cut surface, flow lines 
breaking up into granules. Oblique lines. Oblique light. X 580. 
light. X 580. 
