320 



the jellow amounted to about 1.5' and ap|ieared to vanish in llie 

 orange. 



u^f(üi(/(üiese Antuiionlde (Mn. 35. Sb. 65 = MnSb nearly, Tammann, 

 6^ = 265°). The dispersion curve is given in my first paper (i.e. Fig. 2). 

 The temperature curve, s = ff {t), is represented in table i. Below 

 60° the rotation remains constant. In the neigiibourhood of 80° it 

 begins to decrease and thereafter continues to decrease at a nearl}' 

 Jinear rate. The zero point seems to lie at about 265°. After heating 

 to 205° the rotation rose again to its former value on cooling and, 

 therefore, does not show thermal hysteresis. A second heating gave 

 the two last points near 222° and 245°. Further heating destroyed 

 the mirror. 



'fit) 



TABLE 1. 

 Mn Sb (saturated) 



;. = 567 im 



Binary Iron compounds. 



Iron Carbide I, (Cementite Hilpert, 0^ = 235°). Wologdin found 

 for the transition temperature 180°, which with the apparatus used 

 by him may represent a lower limit. Mauraix observed in the case 

 of high degree carbon steels irregularities below 240°. This was 

 contirmed by Smith, White, Barker and Guild who ultimately extracted 

 the cementite powder from their steel by the Arnold process'). The 



1) M. Wologdin, Coral. Rend. 148, p 776, 1909 ; Ch. Maurain, Compt. Rend. 

 150, p. 779, 1910; Ann. d. Chim. et Pliys. (8) 20, p. 372, 1910; S. W. F. Smith, 

 W. White, S. G Barker und G. Guild, Proc. Phys. Soc. London 24, pp. 62, 

 342, 1912 und 25, p. 77, 1912; I. 0. Arnold, Journ. Iron & Steel Inst. 1, p, 174, 

 1910. 



