110 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Structure of Hypo-eutectoid Steel.* — H. M. Howe and X. G. Levy 

 describe experiments which indicate that, though the precipitation of 

 ferrite, in or below the transformation range, in hypo-eutectoid steel 

 cooling from a higher temperature, is rapid at any given temperature, 

 the coalescence of this ferrite into visible masses is slow if • 4 p.c. car- 

 bon, or more, is present. The masking of the early formed ferrite 

 network is due more to the slowness of coalescence which results in the 

 formation of masses of ferrite within the mesh, than to the balling-up 

 of the network itself. 



Japanese Meteorite. t — M. Chikashige and T. Hiki describe the 

 structure of a meteorite observed to fall at Okano in 1904. Its compo- 

 sition was iron 94 • 85, nickel 4 • 44, cobalt ' 48 and phosphorus * 23 p.c. 

 A section deeply etched with 'nitric acid, showed Neumann lines. Crystals- 

 of rhabdite (phosphorus-nickel-iron), sometimes several millimetres in 

 length, were embedded in a ground mass of hexahedric nickel-iron. 

 The structure was completely changed by heating to a high temperature. 



Eutectic Crystallization.^— R. Yogel discusses the various forms 

 of eutectic structure, and shows that the controlling factors in the 

 crystallization of eutectics are the same as in one-component systems, 

 viz. linear velocity of crystallization, spontaneous crystallization capacity, 

 and flow of heat. Two possible modes of formation of the familiar 

 banded structure are : 1. The successive cr}'stallization of alternate 

 layers of the two constituents, the lamellae formed being at right angles 

 to the direction of flow of heat. - 2. The simultaneous crystallization of 

 the two constituents in the form of rods, parallel to the direction of 

 flow of heat. Experimental investigation appears to indicate that 

 banded eutectic structures are, in fact, formed by the second of these 

 two possible modes of crystallization. 



Standard Magnification for Photomicrographs. §—M. T. Lothrop 

 and C. R. Bulley point out the confusion caused by the great variety of 

 magnifications to be found in published photomicrographs. The authors 

 do not recommend any particular set of standard magnifications, but 

 suggest that such standards be drawn up by a competent committee. 



National Physical Laboratory. || — The etching of steel at high tem- 

 peratures by Baykoff's method, with gaseous reagents such as hydro- 

 chloric acid, was found to be satisfactory at temperatures above 1000° C, 

 but at lower temperatures the products of the reaction remained as a 

 film upon the polished surface, completely masking the structure. The 

 production of " heat reliefs " by heating steel in a vacuum is being tried 



* Int. Zeitschr. Metallographie, iii. (1912) pp. 4-14 (14 figs.), 

 t Zeitschr. Anorg. Chem., Ixxvii. (1912) pp. 197-9 (8 figs.). 

 X Zeitsclir. Anorg. Chem., Ixxvi. (1912) pp. 425-36 (12 figs.). 

 § Proc. Int. Assoc. Testing Materials, ii. (1912) No. 11, 4 pp. 

 II Nat. Phys. Lab. Ann. Report, 1911. 



