ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 403 



Metallography, etc. 



Platinum-antimony Alloys.* — K. Friedrich and A. Leroux have 

 determined the equilibrium diagram for the range 0-91*3 p.c. platinum. 

 The presence of the following phases in the solid alloys has been estab- 

 lished : pure or nearly pure antimony, PtSb 2 and Pt 5 Sb 2 . Pure platinum 

 may exist in the platinum-rich alloys. Pt 5 Sb 2 is the product of a re- 

 action occurring in the solid state. Heat-tinting was employed to 

 render visible the micro-structure. 



Influence of Manganese on the Iron-carbon System.f — F. Wiist 

 gives a comprehensive account of previous work on iron-manganese 

 alloys, with and without carbon, and describes his investigations on 

 thirty-three alloys, prepared by melting pure cast iron with manganese and 

 an excess of carbon. The alloys contained manganese ■ 06-80 ■ 45 p.c, 

 carbon 4 '03-6 "9 p.c. The solidification point of cast iron is somewhat 

 lowered by manganese additions up to 13 p.c. ; it then rises, till at 80 p.c. 

 it is about 1250° C. The "pearlite point" (Ai^) is lowered by small 

 additions of manganese, and at 5 p.c. disappears altogether. Alloys with 

 more manganese contain no pearlite. Manganese increases the capacity 

 of iron for dissolving carbon, and alters the position of the eutectic 

 point. This point in pure iron-carbon alloys lies at 4*2 p.c. carbon, 

 and at 4*05 p.c. when 15 p.c. manganese is present. The presence of 

 manganese favours the formation of troostite and solid solution. Many 

 of the sections, of which photomicrographs are given, were etched with 

 nitric acid in amyl-alcohol. 



Heat-contents of Binary Systems.! — G. Tammann represents the 

 thermal equilibrium of binary mixtures by means of a three-dimensional 

 model, the base of which is the ordinary temperature-concentration 

 diagram. The height of the surface of the model, at any point, is 

 proportional to the heat content of unit mass. Photographs of models 

 corresponding to different cases are given. 



Recalescence Temperatures of Nickel. § — T. A. Lindsay has taken 

 cooling curves of nickel containing less than 2 p.c. of impurities, by 

 the differential method, using copper as the neutral body. In cooling 

 from 900° to 180° C, nickel gives out heat gradually from about 700° 

 to about 285° C. At some points in this range the heat evolution is 

 more rapid, small recalescences occur about 660° C. and 525° C, a larger 

 one from 440°-370° C, and the most marked recalescence from 370°- 

 285° C. 



Melting-point Curves of Binary Alloys. || — D. Mazzotto applies two 

 corrections to the melting-point curve, one depending on the heat of 



* Metallurgie, vi. (1909) pp. 1-3 (13 figs.). 

 t Tom. cit., pp. 3-14 (20 figs.). 



t Zeitschr. Phys. Chem., lxiii. (1908) pp. 129-40 (16 figs.). 

 § Proc. Roy. Soc Edin., xxix. (1908) pp. 57-67 (6 figs.). 



j| Journ. Chem. Soc, xciv. (1908) pp. 6G0-1. See also Nuovo Cim., xv. (1908) 

 pp. 401-22. * 



2 E 2 



