ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 637 



The depression of the transformation point is proportional to the 

 amonnt of the added metal both in the nickel-copper and nickel-tin 

 alloys, but not in the alloys of nickel with silver. The latent heat of 

 transformation of nickel was determined by an indirect method, a mean 

 value of 4 • 4S being obtained. The author concludes from his own results 

 and those obtained by otlier workers that there is no simple relation 

 between the atomic weight of the added metal and the lowering of the 

 transformation temperature of nickel. 



Change of Structure in Iron and Steel.*— AY. Campbell, discussing 

 the equilibrium diagram of the iron-carbon system, takes the view that 

 the same diagram may represent either the solidification of cementite 

 with formation of a cementite-martensite eutectic or the solidification of 

 graphite with the formation of a graphite-martensite eutectic. The 

 author gives the results of some heat-treatment experiments on six high 

 carbon-steels. t A general description of the structure of iron and steel 

 is included, with some notes on the effect of heat-treatment. 



Piping in Steel Ingots. J — A. Obholzer gives his experience of the 

 advantages resulting from the use of thermit to diminish piping. 



Tantalum Steels. § — L. Guillet has examined 4 steels containing' 

 0*09, (J- 15, 0-60 and 1-05 p.c. tantalum, carbon ()-12-0-18 p.c. A 

 ferro-tantalum made in the electric furnace was used in the preparation 

 of the alloys. No special difficulty in melting or in mechanical treat- 

 ment was experienced. The normal steels were found to be pearlitic. 

 Tantalum appears to have a slight hardening effect. The influence of 

 this element on microstructure and mechanical properties is small, and 

 the author concludes that tantalum steels are of little practical interest. 



Relations between the Diagram of Binary Alloys and their 

 Malleability. II — L. Guillet states some general laws deduced from data 

 available, dealing with each possible type of equilibrium diagram. The 

 malleability of an alloy is a function of the malleability of each solid 

 phase and the proportion of malleable to non-malleable phases present. 

 An alloy consisting of a pure compound or a pure solid solution (corre- 

 sponding to a maximum of the liquidus and solidifying at a constant 

 temperature) is not malleable. A solid solution rich in a malleable 

 metal is malleable. Two metals which form a continuous series of solid 

 solutions are either both malleable or both non-malleable, and the 

 alloys have the same characteristics. 



Constitution of Alloys. If — A. Portevin fully describes Tammann's 

 method of thermal analysis, passing in review the numerous cases, 

 corresponding to the different types of equilibrium curve met with 

 in the study of alloys, for which the method has been worked out at 

 the University of Gottingen. The principle of the method is as 



* Journ. Franklin Inst., clxiii. (1907) pp. 407-34 (35 figs.). 

 + See this Journal, 1907, p. 253. 



: -lourn. Franklin. Inst., clxiv. (1907) pp. 1-11 (10 figs.). 

 § C!omptes Kendus, cxlv. (1907) pp. 327-9. 

 II Op. cit., cxliv. (1907) pp. 1273-5. 

 t Key. de Metailurgie, iv. (1907) pp. 797-813 (13 figs.). 



