ZOOLOGY AND BOTANY, MICROSCOPY, ETC. C)79 



carbide, and that the presence of the sulphur renders the carbide stable. 

 The effect of increasing sufficiently the percentage either of silicon or 

 of carbon in an iron-silicon-carbon alloy containing only moderate 

 amounts of these two elements, is to cause the formation of a carbo- 

 silicide of iron. This carbo-silicide appears to be unstable, readily 

 decomposes into graphite and silico-austenite, and is the cause of the 

 greyness of high-silicon cast-iron. 



Ferro-silicon.* — S. R. Bennett reports on the composition and 

 structure of these alloys. Published work is first summarized. Deter- 

 minations of the specific gravity of numerous alloys indicate the probable 

 existence of Fe 2 Si and FeSi, but do not support the existence of FeSi 2 

 or Fe 3 Si 2 . Several alloys were microscopically examined Up to 20 p.c. 

 Si the alloys consist of solid solutions of Fe and Fe 2 Si which are hard,, 

 firm masses giving off little or no gas. Alloys from 20 to 21 '6 p.c. Si. 

 consist of primary crystals of Fe 2 Si in a ground of eutectic composed of 

 Fe 2 Si and Fe Si ; these alloys begin to get more brittle than the lower 

 grades. From 21*6 to 33 • 3 p.c. Si the structure shows FeSi surrounded 

 by eutectic Fe. 2 Si and FeSi ; from 33 • 3 to 60 p.c. Si there are crystals 

 of FeSi in eutectic FeSi + Si ; and above 60 p.c. Si crystals of Si in a 

 field of eutectic FeSi and Si. 



Influence of Antimony and Tin on the Iron-Carbon System.f 

 P. Goerens and K. Ellingen have examined two series of ternary alloys, 

 prepared by the addition at 1350° C. of antimony or tin to molten 

 Swedish pig-iron containing 3 ■ 66 p.c. carbon. One series (11 alloys) con- 

 tained 5*8 to 59*3 p.c. antimony ; the other (12 alloys), to 11 '1 p.c. 

 tin. The carbon content in the antimony series was steadily lowered 

 by the antimony additions, falling to 0*.3 p.c. in the 59*3 p.c. alloy. 

 The effect of tin on carbon content was in the same direction, but was 

 comparatively slight. Cooling curves, chemical analyses, and micro- 

 scopical examination were made. The two ternary systems resemble 

 the iron-carbon-phosphorus system in that a ternary eutectic is formed 

 on solidification. In the antimony series this eutectic solidifies at about 

 950° C. Neither antimony nor tin changes the pearlite-formation 

 temperature. Three constituents were observed in each alloy — pearlite r 

 cementite, and antimonide or stannide of iron. The pearlite is rapidly 

 etched by picric acid and appears dark ; cementite remains white ; anti- 

 monide or stannide become light grey after long etching. Cementite 

 may be distinguished from antimonide or stannide by heat-tinting, the 

 cementite colouring more rapidly in each case. 



Specific and Latent Heats of Molten Cast-iron. :[ — W. Schmidt has 

 determined the total heat evolved when 500 grams of pure cast-iron, 

 containing 4*3 p.c. carbon (about the eutectic composition) cooled to 

 0° C. from 1375°, 1275°, 1175° and 1130° C, the last temperature 

 being just below the solidification point. The cooling took place in a 

 crucible within an ice calorimeter, the temperature being measured by 



* Local Govt. Board Rep., 1908-9. Supplement on nature, uses, and manu- 

 facture of ferrosilicon, 1909, pp. 90-96. 



t Metallurgie, vii. (1910) pp. 72-9 (10 figs.). 

 % Tom. cit., pp. 164-8 (1 fig.). 



