468 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



Influence of Tin and Lead on the Microstructure of Brass.* — 

 F. Johnson has examined microscopically several specimens of brass to 

 which a little tin had been added, and one to which both tin and lead had 

 been added in small amounts. He concludes that tin is only slightly 

 soluble in the a phase of- cast 10 /'M) brass, but is readily soluble in the 

 ,/3 phase of alloys of the naval brass type. The reticulations caused by 

 the presence of tin in a brass in which the ratio of copper to zinc is 2 : 1 

 have no structural relations with any lead present. The lead exists in a 

 free state. The reticulations are due to the deposition of SnCu^ from 

 the metastable yS constituent, which is insufficient in quantity to retain 

 it in solid solution. 



Influence of Oxyg-en on Copper containing Arsenic or Antimony.f 

 R. H. Greaves includes with much other matter a description of the 

 microstructure of specimens of copper, containing from 0*05 toO'G2 p.c. 

 oxygen, together with 0*05 to 0'51 p.c. arsenic ; a similar series con- 

 taining antimony instead of arsenic was also studied. The sections 

 were etched with a 10 p.c. solution of ammonium persulphate. Copper 

 containing oxygen with low arsenic or antimony content, shows dendrites 

 of copper embedded in a ground mass of copper and cuprous oxide, not 

 showing a eutectic structure but occurring in isolated globules. With 

 more arsenic or antimony, the very distinct " cores" observed when little 

 oxygen is present pass into a dendritic form as oxygen content rises. 



Micrographical Studies. J — Particulars of four cases in which micro- 

 scopical examination has proved to be of considerable practical value 

 are communicated by the Atelier des Essais de Mecaux de la Cie. des 

 •Chemins de Fer P.L.M. Arsenic may be rapidly estimated in arsenious 

 copper by etching a polished section with nitric acid for five or six seconds, 

 and comparing it with photomicrographs of standard specimens simi- 

 larly prepared and containing a known percentage of arsenic. Black 

 spots are more or less abundant and voluminous according to the arsenic 

 content. The depth of carburization produced on the edge of steel 

 plates by cutting them with the oxy-acetylene blow-pipe is readily de- 

 termined by examining a polished and etched section. The brittleness of 

 mild-steel screws of large diameter was proved to be the result of the 

 cold-work endured in the screw-cutting operation, and was completely 

 removed by suitable annealing. The adulteration of wrought iron by 

 the insertion of steel bars when piling has been readily detected, and 

 guarded against by a suitable clause in the specification. 



Utility of a Metallographic Nomenclature. § — F. Robin points out 

 the disadvantages of systems of nomenclature based upon the use of 

 proper names, or of names indicating properties, and makes tentative 

 suggestions for a system of rational symbols. Thus, for example, a 

 binary solid solution might be indicated by the symbols of the two 

 metals separated by the letter m. Cu m Ni would signify the solid solu- 

 tion of nickel in copper. In the same manner, eutectics might be sym- 

 bolized by e placed between the symbols of the constituent elements. 



* Journ. Inst. Metals, vii. (1912) pp. 201-17 (12 figs.). 



+ Journ. Inst. Metals, vii. (1912) pp. 218-45 (14 figs.). 



X Proc. Int. Assoc. Testing Materials, ii. (1912) No. 8, 10 pp. (18 figs.). 



§ Proc. Int. Assoc. Testing Materials, ii. (1912) No. 8, 4 pp. 



