262 SUMMARY OF CURRENT RESEARCHES RELATING TO 



diagram is too complex for brief summarising, and in some regions is 

 insufficiently established. The compounds (Cu 2 S) 2 (FeS), (Cu 2 S) 3 (FeS) 2 

 and probably (Cu 2 S) 2 (FeS) 5 , or (Cu 2 S)(FeS) 2 , are indicated by the dia- 

 gram. Concentrated nitric acid was used for etching those sections 

 which required etching. 



Mixed Crystals of Sulphur and Tellurium.* — G. Pellini finds that 

 sulphur and tellurium do not form a compound, but form a series of 

 mixed crystals. A solid amorphous solution of tellurium and sulphur 

 was also obtained. 



Influence of Arsenic and Tin upon Iron.f — C. F. Burgess and J. 

 Aston have studied the magnetic properties of alloys prepared from 

 electrolytic iron, one series containing 0" 29-4 '14 p.c. arsenic, the other 

 series containing 0' 29-2 "06 p.c. tin. Compared with approximately 

 pure iron, the alloys give materially lower hysteresis losses and have a 

 higher permeability. 



Phosphides of Iron. J — H. le Chatelier and S. Wologdine point out 

 that many metallic compounds, which have been described from time 

 to time, are imaginary. Until these supposed compounds are eliminated, 

 by the application of modern metallographic methods of investigation, 

 it is not possible to arrive at any laws governing the formulas of metallic 

 compounds. An examination of the compounds of iron and phosphorus 

 reduces their number from nine to four. The existence of Fe 3 P and 

 Fe 2 P is undoubted, that of FeP and Fe 2 P 3 is very probable, but their 

 formulas are not so well established as those of Fe 3 P and Fe 2 P. 



Alloys of Iron.§ — P. Oberhoffer briefly summarises published work 

 on the binary and ternary alloys of iron. Our knowledge of the equi- 

 librium diagrams is incomplete for the binary systems, and is still less 

 advanced for the ternary systems. 



Heat-treatment of Iron and Steel. || — Methods of heat-treatment 

 suitable for various descriptions of carbon steel are specified. The 

 position of Ac 3, in steels containing not more than ■ 90 p.c. carbon, 

 may be calculated approximately from the formula 



Ac 3 = (900 - 200 c) °C, 



c being the percentage of carbon in the steel. 



W. Campbell f has made further experiments on the removal of 

 " ingotism " by annealing. In a previous investigation he had found 

 that in a steel casting containing - 43 p.c. carbon, the coarse ferrite 

 network was not completely removed at 1180°C, but could not be 

 detected after heating to 1195°C. The present work was done on two 

 pieces of steel castings (a) and (b) containing ' 35 and ■ 5 p.c. carbon 



* Atti R. Accad. Lincei, xviii. (1909) pp. 19-24, through Journ. Ghem. Soc. 

 xcvi. (1909) p. 805. 



t Electrochein. and Met. Ind , vii.(1909) pp. 403-5 (3 figs.). 



% Cornptes Rendus, cxlix. (1909) pp. 709-14. 



§ Metallurgie, vi. (1909) pp. 612-18. 



|| Amer. Soc. for Testing Materials, Proc. ix. (1909) pp. 214-18. (Report of 

 Committee on heat-treatment of steol.) t Tom. cit., pp. 370-7 (12 figs.). 



