310 SUMMARY OF CURRENT RESEARCHES. 



at aboul 800 bo 900 C. After annealing at 900 C. the structure is 

 normal for pure iron, and the metal is soft and ductile. During the 

 heating, hydrogen and smaller quantities of other gases are evolved. 



Slag Inclusions in Steel.* — Specimens of acid steel and of basic 

 steel were rapidly cooled from the liquid state, and microscopically 

 examined by F. (uolitti and Gr. Tavanti. The same specimens were 

 again examined after annealings followed by rapid cooling, and by slow 

 cooling. The various treatments had no appreciable influence upon the 

 form and distribution of the inclusions of reaction slag, and the authors 

 conclude that such slag inclusions are not dissolved in the molten steel. 

 The behaviour of reaction slag appears to be different from that of 

 inclusions consisting mainly of sulphides of manganese and iron. 



Mechanical Anisotropy of Metals. — A. Portevin discusses the 

 irregularity of form of the impression made by the ball in Brinell tests 

 upon metallic specimens in which the crystals and the impression are 

 of the same order of magnitude. Each crystal is anisotropic, and its 

 mechanical properties are a function of direction relative to the crystal 

 structure. When the area affected by the test contains a very large 

 number of crystals, each independent in its orientation, as is commonly 

 the case, the various crystals neutralize each other as regards their 

 anisotropic properties, and approximately circular impressions are 

 obtained. An impression wholly contained within one crystal tends to 

 be square with rounded corners. The form of impressions covering a 

 small number of adjacent crystals, of similar or different orientation, is 

 described. 



Some Metal Failures in Plant.!— S. Evans describes a number of 

 failures occurring in an engineering works, the causes of which were 

 ascertained by microscopic examination of the faulty metal. A steel 

 crosshead of a gas-engine, containing 0"37 p.c. carbon, was considered 

 to have failed owing to its coarse structure, of the Widmanstatten type, 

 which might have been. removed bv suitable heat-treatment. 



'&■ 



* Ann. Chim. Appl. ii. (1914) pp. 360-366, through Journ. Soc, Chem. Ind. 

 xxxiv. (1915), p. 179. 



t Cornptes Kendus, clx. (1915) pp. 344-6. 



j Journ. Soc. Chem. Ind. xxxiv. (1915) pp. 204-207 (S figs.). 



