SEVENTH ANNUAL RECEPTION. 503 



3. Paraffine Ingot cooled slowly. 



4. Paraffine Ingot cooled quickly. 



5. Steel Ingot cooled quickly. 



5.1 Aluminum Ingot cooled quickly, 



3. Evolution of Gas by Metals During Solidification. 



6. Over-poled Copper. 



7. Spitting of Silver. 



8. Steel Casting with Blow-holes. 



9. Steel Ingot with Blow-holes. 



10. Steel Ingot with Blow-holes. 



1 1 . Steel Ingot, Blow-holes prevented by adding aluminum. 



4. Metallography of Steel. 



a. Crystalline Form of the Constituents of Steel. 



1 2. Crystalline form of Ferrite (pure iron). 



13. Crystalline form of Ferrite (pure iron). 



14. Crystalline form of Cementite (FCgC). 



15. Crystalline form of Cementite. 



16. Crystalline form of Graphite. 



b. Micrographs. 



1 7. Ferrite. 



18. Pearlite (eutectic, ferrite and cementite interstratified). 



19. Pearlite with cementite. 



20. Martensite. 



2 1 . Microstructure of Steel as effected by thermal treatment. 



22. Microscope with Section of Pearlite. 



c. Influence of the mode of rupture and of thermal treat- 

 ment on the structure of iron and steel. 



23. Fibrous and crystalline Fracture in the same Bar. 



24. Coarse and fine Fracture in the same Bar. 



25. Series of fractures Representing different Temperatures. 



26. Coarse and fine Fractures in the same Face. 



27. Coarse and fine Fractures in the same Face. 



28. Coarse and fine Fractures in the same Face. 



29. Coarse and fine Fractures in the same Face. 



