510 SUMMARY OF CURRENT RESEARCHES RELATING TO 



system, pure (or nearly pure) copper and a solid solution of copper in 

 silver with a maximum concentration of 6 p.c. Osmond had stated 

 that silver could not hold more than 1 p.c. of copper in solid solution. 

 Lead and copper do not mix in all proportions in the Hquid state. Xo 

 compounds occur : the solid phases are the nearly pure metals. Satisfac- 

 tory agreement with Heycock and Neville's results was found. The 

 ternary system was investigated by taking cooling curves of a large 

 number of alloys. The results are shown as equilibrium curves of 

 31 series, each series containing a constant percentage of one of the 

 metals. The complete system is represented by the usual method of 

 triangular co-ordinates ; the solidification surface is constituted of three 

 portions, any two of which cut each other along a line, while the three 

 meet at the ternary eutectic point (0 • 5 p.c. copper, 2 p.c. silver, 97 • 5 p.c. 

 lead) at a temperature 0" 5-1° C. below the eutectic freezing temperature 

 of the silver-lead system. Microscopic examination confirms the con- 

 clusions based on the equilibrium diagram. 



Variation in Melting Point of Eutectic Mixtures.* — C. Benedicks 

 and R. Arpi point out that though a eutectic, like a pure chemical body, 

 has a definite freezing and melting point, yet it is easy to raise the 

 temperature of a eutectic above its true melting point, while this cannot 

 be done with a pure substance without melting taking place. The 

 influence of size of grain was investigated by mixing together powdered 

 lead and tin in eutectic proportion (30 : 70) and taking heating curves. 

 The size of grain varied in different experiments. The authors found 

 that the larger the grain, the higher was the melting point. The 

 bearing of their results on the difference between the melting points of 

 white and grey iron of the same carbon content is indicated. 



Chemical and Metallographical Studies of Chilled Cast Iron.f — 

 H. Wedding and F. Cremer give the results of an extended research 

 carried out by the latter. A line is introduced into the iron-carbon 

 diagram indicating that in white cast iron the carbon content of the 

 carbon-saturated first separating mixed crystals is greater than in grey 

 cast iron with the same total carbon. The composition of the mixed 

 crystals is a function of the speed of cooling through the solidification 

 range. In grey cast u*on, resulting through slower cooling, the fineness 

 of the graphite flakes appears to be affected by the speed of cooling. 

 The form of the crystals of white iron is characteristic of crystals 

 obtained by the solidification of a super-cooled melt. 



Adams, J. M.— Transmission of Eontgen Rays through Metallic Sheets. 



Proc. Avier. Acad. Arts and Sci., xlii. (1907) 



pp. 671-97 (4 figs.). 

 B'baune, H. — Micrographic Eesearch on Iron and Steel. 



Zentralhl.f. Eisen., ii. (1907) p. 39. 

 „ Nitrogen in Iron and Steel. Tovi. cit., pp. 41-3. 



„ Nitrogen Absorption in the Cementation of Iron. 



Tom. cit., p. 248. 



* Metallurgie, iv. (1907) pp. 416-19 (2 figs.). 



t Stahl und Eisen, xxvii. (1907) pp. 833-8 and 866-70 (25 figs.). 



