ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 379 



the diseases of metals, represented by incipient fractures, slag inclusions, 

 planes of weakness, and metals in which weakness has been produced by 

 improper treatment. 



The second part contains the general methods for the micrographic 

 analysis of carbon steels. The first two chapters are devoted to the 

 technique for obtaining suitable surfaces for microscopical examination. 

 The next chapter describes the primary constituents of carbon steels, and 

 the fourth is occupied with the micrographic identification of the various 

 constituents. Then follows a detailed examination of selected steels, and 

 the influence of annealing and quenching. The last chapter gives the 

 author's theoretical and practical conclusions. 



To this English edition are added two special appendices, one on 

 the apparatus and the method for photographing the metallic surfaces, 

 the other on the relative softness of austenite. 



The volume is well got up, and the index sufficient. 



Influence of Structure upon Strength under Sudden Stresses.§ — 

 R. Job gives an interesting instance of a driving-wheel tyre which 

 fractured in service, while in apparent good condition as to size and 

 extent of wear, and without any indications of internal flaws. Neither 

 analysis nor tensile tests suggested any faults, but microscopic examina- 

 tion of an etched surface from a central section revealed that the 

 structure was excessively coarse and open, thus proving that thorough 

 working of the steel had ceased while the metal was at a high tempera- 

 ture. The material was therefore capable of but relatively small 

 resistance under sudden stress. 



Notes on the Structure of an Alloy which on Freezing Separates 

 into Solid Solutions and a Eutectic.|| — J. E. Stead reproduces a large 

 scale photograph used by Sir William Roberts- Austen in his " James 

 Forrest " lecture, before the Institution of Civil Engineers, April 23, 

 1902, on the structure of phosphorus and iron compounds. Dark 

 octahedral spines represent the unsaturated portions which first solidified 

 and merged into the saturated or white parts surrounding the " land- 

 locked " eutectic itself. 



* Iron and Steel Metallurgist, vii., March 1904, pp. 324-5 (1 fig.). 

 t Tom. cit. pp. 258-9 (1 fig.). 



