522 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Metallography, etc. 



The Metallic Sulphides PbS, Cu.,S, Ag,S, FeS.— K. Friedrich * has 

 attempted an investigation of the equilibrium diagrams of the alloys of 

 these sulphides with sulphur. He gives the melting points ( + 10° C.) 

 as PbS 1120° C, Cu,S 1135° C, Ag 2 S 812° C, FeS 1171° C. The 

 solidification of all the alloys, including the pure sulphides, takes place 

 through a considerable temperature interval. PbS, Ag 2 S, and FeS do 

 not appear to correspond to maxima in the solidification point curves. 

 It might be inferred from these results that none of these four 

 sulphides do in fact correspond to definite chemical compounds. The 

 technical difficulties of investigation, however, are great, and the 

 abnormal results may perhaps be explained otherwise. 



Solubility of Graphite in Iron.f— C. Benedicks discusses the form 

 of the equilibrium diagram of the stable iron-graphite system, from 

 0-2 p.c. carbon. Heyn's view is that graphite is completely insoluble 

 in iron in the solid state, while Ruer's diagram indicates complete in- 

 solubility below a line running from 1000°C. at p.c. carbon to 1140° C. 

 (the eutectic temperature) at 2 p.c. Earlier workers put the limiting 

 temperature much lower. The author gives some experimental results, 

 and indicates the desirability of accurate determinations of the direction 

 of the curve. 



Crystals of Diamond and Carborundum in Steel.} — D. C. 

 Tschernoff in 1868 found small transparent crystals in an ingot of 

 tool steel. A recent examination of some of the same crystals and 

 the steel by F. Osmond has led him to believe they are carborundum. 



Nickel-bismuth Alloys. § — A. Portevin gives a more complete 

 account, with diagrams and photomicrographs, of his determination of 

 the equilibrium diagram. || After pointing out how incomplete reactions 

 occurring during the cooling of an alloy interfere with the applica- 

 tion of thermal analysis, the author describes the experimental work, the 

 results of which point to the existence of two successive and incomplete 

 reactions in the nickel-bismuth system. These may be expressed by the 

 equations — 



(1) At 054° C. : liquid with 6-5 p.c. Ni + Ni ^± NiBi(?) 



(2) At 462° C. : liquid with 3 p.c. Ni + Xi Bi ? ^± Ni Bi 3 

 At 269° C. the eutectic Bi - Ni Bi 3 forms. 



Bromine water was used as an etching reagent. 



Alloys of Silver. IT — This is the first of a series of papers by 

 A. Portevin, in which is to be given an account of the researches on 

 alloys carried out since 1904 in the laboratories of G. Tammann, at 

 Gottingen, and of Kurnakow at St. Petersburg. The industrial metals 

 will be taken in alphabetical order, and the various investigations of the 



* Metallurgie, v. (1908) pp. 23-27, 50-8 (9 figs.). 



t Tom. cit., pp. 41-5 (10 figs.). 



X Rev. de Metallurgie, v. (1908) pp. 79-80 (1 fig.). 



§ Tom. cit., pp. 110-20 (8 figs.). fl See this Journal, 1908, p. 124. 



f Rev. de Metallurgie, v. (1908) pp. 144-66 (32 figs.). 



