260 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Metallography, etc. 



Microstructure of Copper.* — W. Stahl gives photomicrographs of 

 samples of copper taken from the molten bath at different stages in the 

 final refining operation. At the beginning the copper contained 

 0*8-0 '9 p.c. oxygen ; the photomicrograph shows crystallites of cuprous 

 oxide in a ground mass of eutectic. There is a continuous diminution 

 in amount of oxide present till in the refined copper a thin network 

 of eutectic surrounds the grains of copper. 



Physical Properties of Alloys.f — E. Pannain finds that the specific 

 gravity of coinage alloys (bronze and silver-copper alloy) is raised con- 

 siderably by the mechanical treatment involved in the manufacture of 

 the coins. Most of the increase in density occurs in the first rolling. 



Some Zinc Alloys4 — B. E. Curry has determined the equilibrium 

 diagram of the antimony-zinc system by taking heating curves of 27 pre- 

 viously annealed alloys. The diagram thus obtained differs in important 

 respects from that given by Monkemeyer, and to a smaller extent from 

 that given by Zemczuzny. Six solid phases occur in the diagram : pure 

 antimony, pure zinc, the compound ZnSb, and three series of solid solu- 

 tions, a, fi, and y. The a and (3 phases are instable below 437° and 

 405° C. respectively. The y phase is stable only below the solidus. 

 The results demonstrate the inadequacy of cooling curve determinations. 

 The two phases in the zinc-tin diagram are pure zinc and a solution of 

 zinc in tin, having a maximum concentration of about 7 p.c. at 180° C. 

 In the zinc-cadmium diagram the two phases are two solid solutions, 

 zinc in cadmium (maximum concentration 4 p.c. at 217° C), cadmium 

 in zinc (maximum concentration 5 p.c. at 217° C). The liquid melt 

 separates into two layers in the zinc-lead and zinc-bismuth systems. 

 Particulars of suitable etching reagents are given. 



Alloys of Silver with Zinc.§ — N. A. Pushin and M. S. Maximeuko 

 have determined the specific resistances, the temperature-coefficients of 

 the specific resistances, and the thermo-electric forces of alloys of silver 

 and zinc. The existence of the following compounds is inferred : Zn 6 Ag, 

 Zn 4 Ag, Zn 3 Ag 2 , ZnAg, ZnAg 2 (?), Zn 2 Ag (?) and Zn 10 Ag (?). Several 

 series of solid solutions are formed. 



Alloys of Tin and Lead.|| — The linear relation between composition 

 and electrical conductivity of tin-lead alloys appears to indicate that 

 neither compounds nor mixed crystals are formed. On the other hand, 

 the thermal evidence points to the existence of mixed crystals at both 



* Metallurgie, vi. (1909) pp. G09-10 (8 figs.). 



t Atti R. Accad. Lincei, xviii. (1909) pp. 700-1, through Joum. Soc. Chern. Iud., 

 xxviii. (1909) p. 1089. 



J Joum. Phys. Cheru., xiii. (1909) pp. 589-605 (7 figs.). 



§ Journ. Russ. Phys. Chem. Soc, xli. (1909) pp. 500-24, through Joum. Chem. 

 Soc, xcvi. (1909) pp. 539 -40. 



|| Zeitschr. Elektrochem., xv. (1909) pp. 125-9, through Journ. Chem. Soc, 

 xcvi. (1909) p. 319. 



