ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 519 



modern wrouglit-iron. The good state of preservation of the iron was 

 probably clue to a protective coating of slag. 



Lack of Uniformity in Steel Bars.* — In the course of experiments 

 on the tensile testing of reinforcing bars, E. P. Withrow and L. C. 

 Niedner have shown by microscopical examination that the axial region 

 of some of the specimens contained more carbon than the outer layers. 

 The removal of the outer layers by machining accordingly increased the 

 relative strength of the bar. 



Sulphides in Steel. f — J. 0. Arnold and G. R. Bolsover describe 

 the microscopic forms assumed by the sulphides of manganese and iron 

 in a further series of experimental steel ingots. The appearance and 

 nature of a eutectic-like structure, apparently consisting of manganese 

 sulphide and iron, are discussed. 



Internal Fissure in a Steel Axle.J — R. Job describes a micro- 

 scopical investigation which led to the conclusion that an internal 

 transverse oxidized crack in a large steel axle had been caused by 

 stresses, set up by faulty heat-treatment, acting on unsound steel. 



Diffusion of Carbon in Iron.§ — F. W. Adams has heated low-carbon 

 material such as Swedish iron and mild steel, in contact with high 

 carbon steel or cast-iron, in a vacuum, at 900°-1000° C, to determine 

 by the gains and losses in weight, together with the percentage gains 

 and losses of carbon, whether carbon diffuses in the form of carbide or 

 as elemental carbon. The surfaces in contact were previously polished. 

 It was found that no diffusion of carbon occurred unless weldinsr or 



o 



inter-crystallization took place ; thus a determination of the change in 

 weight of each specimen became impossible when carbon diffused from 

 one specimen to the other. 



Iron-silicon-carbon Alloys. || — G. Charpy and A. Cornu-Thenard 

 describe their thermal, microscopical, and chemical investigation of the 

 effect of silicon in iron-carbon alloys. Silicon has a marked influence 

 on the thermal critical points, strongly promotes the separation of 

 graphite, and lowers the solid solubility of carbon in iron at high tem- 

 peratures. 



Annealing of Grey Iron Castings.1" — G. S. Evans describes the 

 softening effect and the changes in microstructure occurring when small 

 grey iron castings are annealed at temperatures not below 700° C. This 

 treatment causes a reduction in the percentage of combined carbon, 

 additional graphite being precipitated by decomposition of carbide of 

 iron. 



* Proc. Artier. Soc. Testing Materials, xiv. (1914) pt. 2, pp. 90-109 (25 figs.), 

 t Journ. Iron and Steel Inst., xci. (1915, 1) pp. 271-5 (-4 figs.). 

 j Proc. Amer. Soc. Testing Materials, xiv. (1914) pt. 2, pp. 76-89 (9 figs.). 

 § Journ. Iron and Steel Inst., xci. (1915, 1) pp. 255-70 (11 figs.). 

 || Journ. Iron and Steel Inst., xci. (1915, 1) pp. 276-305 (32 figs.). 

 i Foundry, xliii. (1915) pp. 219-21 (9 figs.). 



