Phosphorised Portions in Iron and Steel. By J. E. Stead. 289 



nitric acid (Method 3), which leaves the phosphorised portions 

 white on a dark ground. 



Fig. 6. — The same steel as fig. 3, but with 0'5 p.c. phosphorus. 

 Heat tinted (Method 1). 



Fig. 7. — Plates of pure iron with two bands of iron high in 

 phosphorus between them. Etched by the picric acid method. 

 The dark bands represent the parts high in phosphorus. 



Fig. 8. — Alternate plates of pure iron, free from phosphorus, 

 and iron containing 0*25 p.c. of that element. Etched by the 

 iodine method. Illuminated by the oblique light. The piua iron, 

 white, is etched ; the phosphorised portions, dark, have resisted the 

 attack. 



Fig. 9. — Cross section of a rail-head containing 0*08 p.c. 

 phosphorus. Structure developed by the nitric acid method. The 

 dark spots represent minute segregations of phosphorus. 



Fig. 10. — Longitudinal section of a steel tyre, containing about 

 C - 5 p.c. carbon. Etched with dilute iodine, showing that the 

 resist phosphorus lines pass through the normal ferrite and pearlite 

 areas. 



Fig. 11. — Longitudinal section of a heavy crank-shaft, etched 

 slightly with picric acid, showing the terminating point of a 

 phosphorus segregation (white). The carbon has been thrown out 

 of the segregation during annealing, and surrounds it in the con- 

 dition of pearlite (dark). The segregation appeared as a white line 

 nearly two inches in length, and represents what machinists some- 

 times call " phantoms " or " ghosts." As a rule these local segrega- 

 tions are accompanied by sulphide of manganese. In one case an 

 approximate analysis indicated 0*35 p.c. phosphorus, 0*5 p.c. 

 sulphur, and no carbon. The surrounding metal had ■ 04 p.c. 

 phosphorus and " 05 p.c. sulphur. 



June 21st, 1905 



