220 SUMMARY OF CURRENT RESEARCHES RELATING TO 



brium of the thallium-bismuth system, and suggest that the y-phase is a 

 compound of variable composition. In spite of the softness of the 

 alloys, fairly good sections were obtained by the usual cutting and 

 polishing methods, but preparations for microscopic examination were 

 also made by casting on a polished glass plate. With the thallium-rich 

 alloys, however, the casting adhered so strongly to the glass that it could 

 not be separated without spoiling the surface. The sections prepared in 

 the ordinary way had been annealed, and sometimes differed markedly 

 from the glass-cast preparations since the rapid cooling of the latter 

 resulted in incomplete equilibrium. A dilute solution of bromine and 

 hydrochloric acid in water, and a mixture of concentrated nitric and 

 hydrochloric acids were used as etching reagents. 



Influence of Phosphorus on Copper-aluminium Alloys.* — A. A. 

 Read has studied the properties of a number of alloys containing 

 0-11 p.c. aluminium, 0-1 p.c. phosphorus, and describes their micro- 

 structure. The phosphorus remained in solid solution up to about 

 - 2 p.c. Alloys containing more phosphorus showed envelopes of 

 phosphide surrounding the crystals. On annealing, the phosphide was 

 found to ball up. 



Egyptian Metal Antiquities.+ — H. Garland describes the micro- 

 structure of a number of copper and bronze Egyptian tools from 2000 

 to 7000 years old. Cored structures were prominent in some specimens, 

 and the distorted crystalline structures also found were evidence of 

 hammering or similar cold-working. Where re-crystallization had 

 occurred the crystals were small. The author concludes that the 

 structural changes taking place in such metals and alloys at atmospheric 

 temperatures are trifling. 10 p.c. ammonium persulphate solution was 

 found to be the best etching reagent for revealing cores, while chromic 

 acid proved suitable for sharply defining the crystal boundaries. 



Microchemistry of Corrosion.^ — C. H. Desch and S. Whyte have 



carried out corrosion experiments upon three copper-zinc alloys of 

 /? composition. One alloy contained 53 p.c. copper, 47 p.c. zinc ; the 

 other two were similar, but also contained respectively 1 p.c. tin and 

 1 p.c. iron. A surface finished on fine emery-paper was made the 

 anode in a 5 p.c. solution of sodium chloride, the cathode being a 

 platinum wire. An E.M.F. of 3 volts was applied. Corrosion was 

 found to take place by removal of zinc from a surface layer, a skin of 

 nearly pure copper remaining. This copper skin was not united to the 

 alloy below by any zone of intermediate composition, the boundary 

 between copper skin and unchanged alloy being quite sharp. The 

 copper skin showed the outlines of the /? crystals from which it was 

 derived ; it could be peeled off, leaving clearly visible the microstructure 

 of the unchanged alloy beneath. Indications that corrosion began at 

 the boundaries of the crystal grains were obtained. 



* Journ. lust. Metals, x. (1913, 2) pp. 344-70 (16 figs.), 

 t Journ. Inst Metals, x. (l!»13, 2) pp. 329 43 (14 figs.). 

 X Journ. Inst. Metals, x. (1913, 2) pp. 304-28 (11 figs.). 



