362 PROCEEDINGS OF THE SOCIETY. 



cause of the so-called fibrous appearance of wrought iron. The ferrite 

 is not really pure " ferrite," but a solid solution containing small per- 

 centages of silicon and other impurities. 



Ref. : " Metallography " (Sauveur), chap. vi. with figs. ; " Value of 

 Science in the Smithy and Forge " (Cathcart), pp. 48, 49 and 

 figs. 



3. Geey Pio Iron. — R.No. : 912. Analysis : c.c. 0*52 p.c, graphite 



3 • 5 p.c. Treatment : As cast. 3fa(/. : x 100. 



Matrix (white) of ferrite — darker parts pearlite — long black inclusions 

 graphite. (The graphite has probably been removed in polishing. Only 

 the cavities originally containing it remain.) 



Ref.: "Metallography" (Sauveur), chap. xxii. ; "Microscopical 

 Analysis of Metals" (Stead) [hereinafter called "Micro- 

 Analysis" (Stead)], figs. 119 and 120. 



4. White Pio Irois". — R. No, : 913. Analysis : c.c. '^ ^.c. Treatment', 



As cast. Mag. : x 150. 



Light background cementite FegC. Finely divided structure, 

 pearlite. Laminated dark areas, sorbite. 



Ref. : "Metallography" (Desch), p. 376, pi. xiv. A and b. 



5. Low Carbon Steel. — R. No.: 1350. Analysis: c.c. 0"17 p.c, 



Mn 0*4 p.c. Treatment: Annealed. May.: x 100. 



Polyhedral grains of ferrite ; at the boundaries may be seen small 

 areas of pearlite which under higher magnification show the typical 

 laminated structure. Throughout the range of carbon steels np to 

 • 9 p.c. carbon, a gradual increase in the amount of pearlite present 

 will be noticed. 



Ref. : " Metallography " (Sauveur), chap, xv., fig. 234. 



6. Low Carbon Steel. — R.No.: 428. Analysis: c.c. 0*17 p.c, 

 Mn 0-4 p.c Treatment : Quenched 900° 0. water. Mag. : x 100. 



The effect of heat treatment is here seen to consist in the breaking 

 up of large areas of pearlite, and a close-grained homogeneous structure 

 is obtained. 



Ref. : " Metallography " (Sauveur), chap, xv., fig. 229. 



7. Low Carbon Steel.— i?. No.: 429. Analysis: c.c. 0*17 }).c, 



Mn 0-4 p.c Treatment: Quenched 900" C. water, 400° C. air. 



Mag. : X 100. 

 This is a tempered specimen in which the treatment has been less 

 drastic ; consequently tlie structure is inteimediate between Nos; 428 

 and 1350. 



Ref. : '• Metallography " (Sauveur), chap. xv. p. 239 et seq. 



