120 SUMMAEY OF CURRENT RESEARCHES. 



reagents, and demonstrating the superiority of the reagent recommended, 

 are given. The persistence of phosphorus segregation throughout heat- 

 treatment is also ilhistrated. 



'' Grhost-lines " in Steel Forcings.* — A few minutes after the 

 completion of the casting of an octagonal ingot of nickel-chromium 

 steel, weighing about 57 tons, a burst-out occurred at the bottom, and 

 about 17 tons of steel escaped. A hollow shell w-as thus produced in 

 the upper part of the ingot, and in each internal angle of this shell 

 a series of protruding ribs was found. J. 0. Arnold has examined these 

 projections, which he regards as "ghosts." They were found to contain 

 considerably more carbon, sulphur, phosphorus and nickel than the 

 surrounding steel, and to have micro-structures corresponding with 

 their composition. The author considers that the occurrence of these 

 segregated projections indicates that the ghosts in steel are the portions 

 which solidify first, not last, as commonly believed. 



Surface-markings caused by Quenching.f — B. Bogitch describes 

 a phenomenon apparently due to surface deformations. Small plates 

 of annealed mild steel were polished, heated to temperatures between 

 200° and 400° C, and quenched in water. Surface-markings, the 

 appearance of which depended on the temperature from which the 

 specimens were quenched, were produced The height of the " folds " 

 was extremely minute. 



The Constituent Alite of Portland Cement Clinker. J — E. Jiinecke 

 shows by thermal and microscopic evidence that alite, the chief con- 

 stituent of Portland cement clinker, is a definite compound of the 

 formula sCaO, AI2O3, 2810^. Photomicrographs in colour, taken with 

 polarized light from thin sections, are given to establish that the 

 compound obtained by melting the powdered oxides together in the 

 electrical arc is identical with alite. 



* Journ. Inst. Mech. Eng., 1915, pp. 653-72 (7 figo.). 



t Comptes Rendus, clx. (1915) pp. 768-71 (1 fig.). 



t Zeitschr. Anorg. Chem., Ixxxix. (1914) pp. 355-69 (10 figs.) 



