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BELL SYSTEM TECHNICAL JOURNAL 



Fig. J 



(b) Showing inappreciable depth of carbiirized zone, and a large non- 

 metallic inclusion in the steel. Inclusions of this sort denote poor 

 quality or dirty steel. Magnification, 100 X. 



Fig. K. Steel of 1.5% carbon lualnl tn S2.i° C. and iincnched in oil. Tliis 

 medium-power photomicrograph at 100 X really tells very little about the steel, 

 except that it possesses a fine structure. 



