ON THE DEPENDENCE OF VALENCE UPON VOLUME IN CERTAIN TRIVALENT ELEMENTS

A. Ludwig
1909 Journal of the American Chemical Society  
Ex-Ob- Ex- Ob-Temp. Total. ternal. served. Mills. Dieterici. Temp Total. ternal. served. Mills. Dieterici. -30' 75.2 9.86 65.34 65.74 6 6 . 2 5 -25' 66.90 12.00 54.90 58.62* 54.77 -20 6 9 . 0 8.70 60.30 j 9 . 6 0 j9.38 -20 65.04 11.88 53.16 56.88* 53.52 o 56.2 j . 8 4 48.36 48.25 48.41 o 5 8 . 2 9.68 48.52 4;.?0* 44.83* 20 35.0 5 . 2 2 29.78 31.33* 31. 2v* 20 40.0 7.09 32.91 34.22* 3 2 . j4 2 5 26.0 3 . 9 3 2 2 . 0 7 24.50* 2 4 . 3 2 * 30 2 2 . 5 ,j.13 17.37 24.54* 23.55* 30 11.0 2.15 8.85
more » ... 11.0 2.15 8.85 13,71* 13,55* 38.8 u o o ci 0 31.35 o o o o In a paper on the melting point of carbon, published in the year 1902,' the cessation of the electrical conductivity during the melting of carbon under a high gas pressure was thought to he an indication of the passage of a less dense form of carbon into the more dense form of diamond. On account of the relatively high inversion temperature, more than 3000 O, and the necessarily extreme pressure, a more complete study of this reaction appeared for the moment almost impossible. I t seemed much more promising to investigate the volume changes of some other conducting material which would be easier to melt. The element bismuth appeared to me particularly adapted for this purpose, not only on account of its low melting point, 265') but also on account of its relatively large increase of density (about 3 per cent.) on melting. I was aware that neither Spring2 nor Kahlbaum3 succeeded in producing a permanent change in the volume of bismuth, even with very high pressures (over 10,000 atmospheres). But as those scientists applied the pressure a t ordinary temperature only, I undertook to heat the metal up to the melting point and to prevent its expansion in passing into the solid state by the application of very high pressures. The material used for the purpose was 9 9 . 6 per cent. pure bismuth, with traces of antimony, lead, copper and iron. Tammann4 calculates the lowering of the melting temperature for bismuth through pressure from the formula A t = o.ooj86 ( p --I).
doi:10.1021/ja01940a002 fatcat:buu4wbgexzgefdajawy2vfqdim