. Transactions. :i\ Fig. 15.—Same as Fig. 14. Etched 10 sec. with 4 per cent, nitric acid. X Fig. 16.—Norway iron treated 20 hr. at (350° C. in synthetic ammonia, SHOWING TYPICAL SMALL NEEDLES. EtCHED 10 SEC. WITH 4 PER CENT. NITRIC 500. H. E. WHEELER 269

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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries