ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 507 



tin, 39-8 bismuth, 27-5 cadmium atomic p.c. The compound Sn4Cd 

 is formed in both systems : its normal temperature of formation is 125° C. 



Lead-thallium and Lead-indium Alloys.* — N. S. Kurnakow and 

 N. A. Puschin have determined the equilibrium curves of these two 

 systems. The freezing-point curve of the lead-thallium alloys rises from 

 the melting points of both metals to a maximum at 380° C. (38-40 

 atomic p.c.lead), and shows a sudden change of direction at 310 '4° C. 

 (5 '5 atomic p.c. lead). The equilibrium curve of the lead-indium 

 system is simple, and indicates a continuous series of solid solutions. 

 The micro-structure of the alloys was investigated. 



K. Lewkonjaf has also determined the equilibrium diagram of the 

 lead-thallium system ; there are important differences between his results 

 and those obttiined by the above authors. The maximum at 374° C. is 

 held to indicate the compound PIjTL. 



Effect of Stretching on Conductivity. J — J. A. Donaldson and 

 R. Wilson have determined the specific resistance and density of lead 

 wires, permanently stretched to different extents. The change in con- 

 ductivity produced was found to be small, and appears to be within the . 

 limits of experimental error. 



Thermal and Electrical Effects in Soft Iron.§ — E. H. Hall, 

 L. L. Campbell, S. B. Serviss, and E. P. Churchill, in carrying out their 

 intention of determining the various properties of the same specimen of 

 soft iron, have obtained the following additional results.|| Temperature 

 coefficient of thermal conductivity between 115° and 204° C. referred to 

 the value at 115° = —0*00068 approximately. Electric resistance,, 

 absolute, 17260 at 100° C. and 26140 at 218-2° C, with a mean tem- 

 perature coefficient 0*00661 (on the basis of the value at 0° C.) between 

 100° C. and 218° C. Values for the Thompson effect coefficient are 

 given. 



Specific Heat of Iron at High Temperatures.lf — J. A. Harker 

 determined the total heat evolved by iron of a high degree of purity, in 

 cooling from temperatures ranging from 216° C. to 1144° C. to ordinary 

 temperatures. The specimens, enclosed in porcelain protecting tubes, 

 were heated in an electric resistance furnace to the required temperature, 

 then dropped into a thin-walled vessel containing light magnesia, 

 surrounded by the water of the calorimeter. The results indicate that 

 the specific heat rises up to about 900° C, then falls considerably. 



Tin-nickel Alloys.** — L. Guillet criticises severely the purely 

 chemical methods employed by Vigouroux for examining alloys, and 

 contends that the determination of equilibrium diagrams and investiga- 

 tion of microstructm'e must foi^m the basis of all study of alloys. The 



* Zeitschr. Anorg. Chem., lii.(1907) pp. 430-51 (9 figs.). 

 t Tom. cit., pp. 452-6 (1 fig.). 



X Proc. Roy. Soc. Edinburgh, xxvii. (1907) pp. 16-20. 

 § Proc. Amer. Acad. Arts and Sci., xlii. (1907) pp. 597-626 (2 figs.). 

 II See this Journal, 1905, p. 667. 



t Coll. Researches Nat. Phys. Lab., ii. (1907) pp. 207-14 (2 figs.). 

 ** Rev. de M6tallurgie, iv. (1907) pp. 535-51 (17 figs.). 



2 L 2 



