700 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Gold-magnesium Alloys.* — R. Vogel has determined the equilibriums 

 diagram by the method of thermal analysis, and confirmed it by micro- 

 scopic examination of alloys. The system is compared with the gold- 

 cadmium and gold-zinc systems. Three maxima indicate the occurrence 

 of the compounds AuMg, AuMg 2 , AuMg 3 . Three series of solid 

 solutions occur. 



Tin-lead Alloys.!— P. N. Degens has redetermined the equilibrium 

 diagram. The quantity of alloy used for cooling curves was about 

 160 grams, and the cooling from 800-100" C. occupied 25-35 minutes. 

 The freezing point curve indicates complete miscibility in the liquid 

 state, the formation of a eutectic freezing at 181° C. and containing 

 24 - 4 atomic p.c. lead, a solid solubility of tin in lead of 12 atomic p.c, 

 a very small solid solubility of lead in tin, and gives no evidence of the 

 formation of compounds. In alloys containing 0-88 p.c. lead a thermal 

 critical point was found at 146' J C., and the occurrence of a change at 

 this temperature was confirmed by dilatometric measurements. The 

 author holds that a compound separates at 146° C. Lead-rich alloys 

 were etched with a 5 p.c. solution of acetic acid in ethyl-alcohol. 



Sub-oxides of Caesium.J — The solubility of metallic oxides in the 

 molten metals has some important practical bearings in metallurgy. 

 For the study of this phenomenon Rengade has selected caesium 

 because of its low melting point and its capacity for holding in solution 

 a large amount of oxide. The caesium-oxygen system was studied by 

 the method of thermal analysis. The equilibrium diagram given was 

 derived from data yielded by heating curves in preference to cooling 

 curves, as the supercooling observed in the solidification of the melts 

 rendered the indications of cooling curves uncertain. The operations 

 were carried out in vacuo or in an atmosphere of nitrcgen. Starting 

 with the pure metal, melts of increasing concentration in oxygen were 

 obtained by admitting, successively, known quantities of oxygen to the 

 glass tube containing the caesium. The compounds found were Cs 7 0, 

 Cs 4 0, Cs T Oo, Cs 3 0, Cs 2 0. Three eutectic points were observed, one 

 belonging to a labile equilibrium. No solid solutions occur. Some 

 microscopic observations were made. 



Physico-chemical Studies in Tin.§ — E. Cohen has studied the 

 occurrence of " tin-pest " in old coins, and ascribes it to the change 

 from the usual form of tin to the brittle-grey variety, taking place 

 below 18° C. 



Basic Bessemerising of Copper-matte. |] — F. Schreyer, in the course 

 of investigations on this subject, has made a metallographic study of the 

 system FeO - Fe 2 3 with indefinite results. Sections cut from fused 

 mixtures of the oxides, in different proportions, were polished and etched 



* Zeiteckr. Anorg. Chem., lxiii. (1909) pp. 169-83 (13 figs.). 



t Tom. cit., pp. 207-24 (18 figs.). 



t Rev. MetaUurgie, vi. (1909) pp. 934-45 (5 figs.). 



§ Zeitschr. Phys. Chem., lxiii. (1908) pp. 625-34 (15 figs.). 



|| MetaUurgie, vi. (1909) pp. 190-7 (22 figs.). 



