. Transactions. Fig. 29.—Same as Fig. 27; junction of light and dark areas. 15 sec. with 4 per cent, nitric acid. X 500. H. E. WHEELER 279. Fig. 30.—Same as Fig. 29; nearer to dark area. Martensitic. Etched 15 SEC. WITH 4 per cent. NITRIC ACID. X 500.

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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries