556 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Metallographie Notes.* --H. le Chatelier describes the micro- 

 structure of a variety of specimens. Titanium of different degrees of 

 purity, carbide of titanium, carbide of aluminium, cast iron quenched in 

 the experiments on the artificial production of diamond — all these being 

 specimens prepared by Moissan in the electric furnace — were examined. 

 The effect of cold-work in promoting the growth of crystalline grain in 

 mild steel upon subsequent annealing between Goo and 700° C, was 

 clearly shown by a specimen furnished by Charpy. This had been im- 

 pressed by a Brinell ball, then annealed, and machined level with the 

 bottom of the impression. The polished and etched specimen showed a 

 ring of exceedingly large crystals, corresponding to the region which had 

 undergone the greatest distortion in the test. The structure inside and 

 outside this ring was much less coarse. The author's remarks on the 

 disintegration of aluminium are dealt with in the preceding abstract. 



Alloys of Sodium "with Silver and Gold.f — C. H. Mathewson has 

 worked out the equilibrium diagrams of the sodium-silver and sodium- 

 gold systems by thermal, microscopical, and chemical methods. Sodium 

 and silver form no compounds, and each is soluble in the other in the 

 solid state only to a minute extent, if at all. Sodium and gold form 

 one compound, Au 2 Na. The concentration of any solid solutions is 

 extremely small. 



Ternary System, Silver-tin-lead.J — X. Parravano has investigated 

 this ternary system by determining, by thermal methods, the equilibrium 

 diagrams of a number of sections, parallel to the silver-tin side, of the 

 triangular ternary diagram. Cooling curves were taken of 102 alloys, 

 falling into 13 series, each series containing a constant percentage of 

 lead. Confirmation of the thermal results was obtained microscopically ; 

 a 10 p.c. solution of acetic acid in alcohol was used for etching. Four 

 solid phases exist : mixed crystals of silver and tin, mixed crystals of 

 lead and tin, the compound Ag 3 Sn, and pure tin. A ternary eutectic 

 melting at 175° C. was found. 



'& 



Ternary Alloys of Lead, Tin and Antimony.§ — R. Loebe has deter- 

 mined the equilibrium diagram of this ternary system by thermal 

 methods, confirming his conclusions by microscopical examination of 

 the alloys. Cooling curves were taken of some 200 alloys, falling into 

 12 series ; each series formed a section across the triangular diagram. 

 In the binary systems, lead-antimony and lead-tin, the components are 

 insoluble in each other in the solid state, while iu the tin-antimony 

 system three series of solid solutions occur. The position and form of 

 i lie four surfaces of primary crystallization of the ternary system were 

 established, but owing to the slow rate of diffusion in the solid state, 

 and also to the segregation caused by differences in specific gravity 

 between some of the phases, the position of the solidus surfaces could 

 not be fixed with certainty. Xo ternary eutectic point was found, the 

 binary eutectic tin-lead having the lowest melting-point. The ternary 



* Rev. Metallurgie, viii. (1911) pp. 367-76 (14 figs.). 

 t Internat. Zeitschr. Metallographie, i. (1911) pp. 51-63, 81-8 (14 figs.). 

 I Iutemat. Zeitschr. Metallographie, i. (1911) pp. 89-108 (32 figs.). 

 § Metallurgie, viii. (1911) pp. 7-15, 33-49 (79 figs.). 



