406 SUMMARY OF CURRENT RESEARCHES RELATING TO 



nickel, and zinc, and a continuation of the study of the crystalline 

 structure and mode of solidification of eutectic alloys. 



Platinum-lead Alloys.* — N. A. Puschin and P. N. Laschtschenko 

 have studied this system by the electric potential method, and have 

 found two compounds, PbPt and Pb 2 Pt. The existence of these com- 

 pounds was confirmed by microscopic examination of the alloys. 



Alloys of Silicon. — S. Tamaruj has investigated the silicon-tin, 

 silicon-lead, and silicon -thallium systems. Silicon does not mix in the 

 molten state with either lead or thallium, but mixes in all proportions 

 with tin. There are no compounds in the silicon-tin system. The 

 three equilibrium diagrams are given. 



Pt. Vogel | finds that magnesium and silicon are miscible in all 

 proportions in the liquid state, form one compound Mg 2 Si, two eutectics 

 (42 and 96 p.c. magnesium), and no solid solutions. Mg 2 Si melts at 

 1102° C. The equilibrium diagram deduced from the thermal data, 

 and confirmed by microscopic examination, is given. Dilute hydro- 

 chloric acid was used for etching. 



Silicon-magnesium System.§ — P. Lebeau and P. Bossuet conclude 

 from microscopic and chemical evidence that SiMg 2 is the only com- 

 pound that silicon forms with magnesium. The alloys were prepared 

 by melting magnesium filings with crystals of silicon, a small quantity 

 of potassium fluosilicate being added, or by heating magnesium with a 

 mixture of fluosilicate of potassium and magnesium. Alumina was 

 used for polishing, but scratches could not be avoided. Alloys contain- 

 ing little silicon were observed to be grains of magnesium surrounded 

 by a eutectic. At about 2 p.c. silicon, crystals of a silicide began to 

 appear, and the 36*15 p.c. silicon alloy consisted wholly of this silicide. 

 With further increase of silicon another eutectic appeared, and alloys 

 with more than 50 p.c. silicon were observed to contain crystals of free 

 silicon. The structure of many of the sections was visible after polishing, 

 while dilute hydrochloric acid was used for etching others. The com- 

 position of the silicide was established by analysis of crystals isolated by 

 dissolving out the magnesium in a 25 p.c. Si alloy with ethyl iodide in 

 anhydrous ether. 



Alloys of Manganese.||— G. Arrivaut has applied chemical methods 

 to the study of the binary alloys of manganese with numerous other 

 metals. The alloys were prepared from pure materials in magnesia 

 crucibles by the aluminothermic process or by melting the metals 

 together in the absence of air. The alloys were treated with various 

 reagents (acids, alkalies, etc.) in such a way that only the manganese 

 was dissolved, the other metal remaining in the residue. According to 

 the nature of this residue the alloys are divided into two classes : 

 (1) those from which one or more constituents corresponding to simple 



* Zeitschr. Anorg. Cbem., lxii. (1909) pp. 34-9 (1 fig.). 

 t Tom. cit., pp. 40-5 (3 figs.). % Tom. cit., pp. 46-53 (7 figs.). 



§ Rev. Metallurgie, vi. (1909) pp. 273-8 (8 figs.). 



il Mem. Soc. Sci. Phys. Nat. de Bordeaux, ser. 6, iv. (1908) pp. G7-1G0 

 (20 photomicrographs). 



