668 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Metallography, etc. 



Structure of Coinage Bronze.* — F. diiolitti and E. Pannain have 

 si in lied the microstructure of Italian coinage bronze, containing 95 ■ 8 p.c. 

 copper, 3 - 82 p.c. tin, and 0'38 p.c. impurities. The polished sections 

 were repeatedly etched with hot nitric acid ' 24 p.c, and were gently 

 repolished with chromium oxide after each etching. The alloy as cast 

 was found to consist of the solid solutions a and /3, thoughua bronze of 

 this composition should consist entirely of a. The presence of /3-crystals 

 is due to the speed of cooling, which is too great to permit of the estab- 

 lishment of equilibrium between the first u-crystals and the liquid. The 

 concentration of the liquid in tin thus increases beyond the theoretical 

 value, and the /3-crystals, rich in tin, result. The /3-crystals were not 

 removed by heat treatment. The authors investigated the effect of 

 mechanical work on the alloy. 



Arsenic and Antimony in Copper.f — A. H. Hiorns and S. Lamb 

 have studied the influence of small quantities of arsenic and antimony 

 on copper. Thirteen alloys were prepared containing 0*05 to 2'9p.c. 

 arsenic, and thirteen alloys containing • 1 to 8 ' 5 p.c. antimony. Various 

 physical tests were carried out, and sections for microscopic examination 

 were cut transversely from' both quickly and slowly cooled ingots. Both 

 series of alloys were found to consist of dark soft crystals, surrounded 

 by a lighter and harder constituent which increased in .quantity as the 

 proportion of the foreign element was greater. In the slowly cooled 

 alloys small quantities of bodies, which appeared to be the chemical com- 

 pounds Cu 3 As and Cu 3 SI>, were noted. 



Gold-tellurium Alloys.^ — H.Pelabon has determined the solidifica- 

 tion temperature curve of the gold-tellurium system. A eutectic con- 

 taining 16 '5 p.c. gold solidifies at 415° C. A maximum (472° C.) at 

 41 to If) p.c. gold indicates the existence of a definite compound, which 

 appears to correspond to the mineral calaverite Au 2 Te 4 . From 45 to 56 p.c. 

 gold the curve falls to 452° 0., the melting-point of tellurium. All the 

 alloys containing more than 56 p.c. gold solidify at 452° C, but at higher 

 temperatures are increasingly pasty as the content of gold is greater. No 

 indication of the existence of Au 2 Te was obtained. 



Cobalt-tin Alloys. § — S. F. Zemczuzny and S. W. Belynsky give an 

 equilibrium diagram obtained by thermal methods and confirmed by 

 microscopic examination of the alloys. Two compounds, Co 2 Sn and 

 CoSn, and two eutectics were found. CoSn is non-magnetic, as are also 

 all the alloys with less cobalt than this compound. 



Boiling-points of Metals. || — H. C.Greenwood has employed a vertical 

 carbon tube resistance furnace; in it was suspended a long graphite 



* Atti R. Accad. Liucei, xvii. (1908) pp. 068-70, through Journ. Chem. Soc, 

 xcvi. (1909) pp. 144-5. 



t Journ. Soc. Chem. Ind., xxviii. (1909) pp. 451-7 (8 figs.). 



X Comptes Rendus, cxlviii. (1909) pp. 1176-7. 



§ Zuitschr. Anorg. Chum., lix. (1908) pp. 364-70 (7 figs.). 



|| Proc. Roy. Soc, Series A, lxxxii. (1909) pp 396-408 (2 figs.) 



