ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 249' 



The Distribution of Phosphorus in Steel between the Points 

 Acl and Ac3.— J. H. Whiteley (Iron and Steel Institute Meeting, 

 May, 1920). Details are given of methods for etching phosphoretic 

 steels for microscopical analysis, and further work has been undertaken 

 on the subject of " ghost-lines." 



Some Defects in Electro-deposited Iron. — W. E. Hughes (Iron 

 and Steel Institute Meeting, May, 1920). The author concludes that 

 electrolytic iron is prone to a number of defects that make it unsuitable 

 for engineering purposes. The view that its hardness is due to the 

 presence of hydrogen is called in question. 



Silica Brick from the Roof of an Open-hearth Furnace.— J. E. 

 Stead {Trans. Ceramic Soc, 1918-19, 18, 389-98). A silica brick 

 from a Middlesbrough furnace had been reduced in size from 

 12 in. X 6 in. X 3 in. to 12 in. x 2| in. x 2| in. The results of micro- 

 scopical examination of this brick are given. 



The Microstructure of Zinc Retorts. — A. Scott {Trans. Ceramic 

 Soc, 1918-19, 18, 512-15). Two types of zinc silicate are present. 

 The spinel crystals forming one of the chief constituents of used zinc 

 retorts are identical with gahnite, ZnAloO^. 



Effect of Nitrogen on Steel.— Geoege F. Comstock and W. E. 

 Ruder {Chemical and 3Ietallurgical Engineering, March 3, 1920, 22, 

 No. 9). A resume of the important literature on amount of nitrogen in 

 various classes of steels, its method of occurrence and effect on physical 

 properties, together with some recent experiments on its action during 

 heat treatment. 



Nature of the Defects revealed by the Deep Etching of Trans- 

 versely-fissured Rails. — Henry S. Rawdon {Chemical and Metal- 

 lurgical Engineering, March 17, 1920, 22, No. 11). Microscopic studies 

 which show that "gashes" developed by deep etching of polished 

 surfaces correspond to tightly closed intracrystalline cracks ; they may 

 be discovered by dipping a magnetized specimen into a suspension of fine 

 iron dust. 



Genesis of Ferrite. — Federico Giolitto {Chemical and Metal- 

 lurgical Engineering, April 21, 1920, 22, No. 16). Contrary to 

 commonly accepted ideas, the ferrite in hypo-eutectoid steels is not 

 extruded as a shell to the outside of austentic kernels, but exists as an 

 aggregation of crystals essentially discontinuous at the low-carbon nuclei 

 of solid solution grains. 



Copper and Magnetite in Copper Smelter Slags. — Charles G. 

 Maier and G. D. Yan Arsdale {Chemical and Metallurgical Engineer- 

 ing, June 16, 1920, 22, Nos. 24-5). Chemical and microscopic 

 examination of a series of representative slags, showing how copper 

 losses occur, the relation of magnetite to copper loss, the behaviour of 

 converter slags in reverberatory furnaces, and suggestions for reducing 

 copper slag losses. 



