318 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Metallography, etc. 



Silver and Cuprous Oxide.*— C. H. Mathewson and C. H. Stokes- 

 bury find that cuprous oxide dissolves freely in molten silver, but is 

 practically insoluble in tke solidified metal. Thus silver and copper are 

 alike in their behaviour towards cuprous oxide, silver and cuprous oxide 

 forming alloys containing a eutectic. The eutectic contains 1*3 p.c. 

 Cu 2 0. As in the copper-cuprous oxide alloys, the cuprous oxide coalesces 

 readily. The primary crystals of silver tend to encroach on the eutectic 

 areas. The structure is apparent in polished sections, but a mixture of 

 concentrated ammonia and hydrogen peroxide has been found suitable 

 for etching. 



'to - 



Alloys of Cerium with Silicon and Bismuth.t — R. Yogel has' 

 made extensive use of microscopic examination in the determination of 

 the equilibrium diagrams of the cerium-silicon and cerium-bismuth 

 systems. The compound CeSi, melting above 1500° C, was observed in 

 unetched sections as yellow rounded crystallites. The eutectic of CeSi 

 and silicon had a well-formed lamellar structure. Free silicon was found 

 as hard needle-shaped crystals. The cerium-bismuth alloys were polished 

 with alumina on wet cloth, but oxidized very rapidly. The structural 

 characteristics of the four compounds and the eutectics occurring in the 

 cerium-bismuth system are described. 



Metallography of Electrolyticaliy- deposited Alloys. £ — R. Kre- 

 mann, C. T. Suchy, and R. Maas find that iron-nickel alloys deposited 

 electrolyticaliy from a solution of ferrous and nickel-sulphates are analo- 

 gous in structure to alloys prepared by fusion. A structure characteristic 

 of the electrolytic alloys consisted of concentric layering*. Cross-sections 

 of the deposits had a lamellar appearance. 



Protective Oxidized Coating on Sheet-iron. §— Matweeff has exam- 

 ined microscopically transverse sections of thin Russian sheet-iron used 

 for roofing ; this material is remarkably resistant to corrosion. The 

 specimens were embedded in gum-lac for polishing. The layer of oxide 

 was not homogeneous, and consisted of compact ferrous oxide which 

 could be polished, intermixed with friable and porous magnetic oxide. 

 Protection against corrosion appears to be conferred by the magnetic 

 oxide, which is retained in position by a kind of skeleton of the 

 mechanically stronger ferrous oxide. 



Crystallizing Properties of Electro-deposited Iron.||— J. E. Stead 

 and H. C. H. Carpenter have studied the structure of pure electro- 

 deposited iron strip containing 99'9G7 p.c. iron, subjected to various 



* Int. Zeitschr. Metallographie, v. (1914) pp. 193-212 (12 figs.), 

 t Zeitschr. Anorg. Chern., lxxxiv. (1913) pp. 323-39 (10 figs.) 

 X Monatsh. Chern., xxxiv. (1913) pp. 1757-1809, through Journ. Chern. Soc, cvi. 

 (1914) pp. 96-7. 



§ Rev. Metallurgie, xi. (1914) pp. 480-2 (5 figs.). 



|| Jouru. Tron and Steel Inst., lxxxviii. (1913", 2) pp. 119-70 (41 figs.). 



