Assuming the density of Bi to be 9.8, and neglecting corrections for heat dilatation, his value for the susceptibility at 20°C. is equivalent to κ = −13.23 × 10−6. As the temperature was raised up to 273°, κ gradually fell to −9.38 × 10−6, rising suddenly when fusion occurred to −0.37 × 10−6, at which value it remained constant when the fluid metal was further heated. Fleming and Dewar give for the susceptibility the values −13.7 × 10−6 at 15°C. and −15.9 × 10-6 at −182°, the latter being approximately equivalent to Κ × 106 = −1.62. Putting t° = −182 in the equation given above for Curie’s results, we get Κ × 106 = −1.66, a value sufficiently near that obtained by Fleming and Dewar to suggest the probability that the diamagnetic susceptibility varies inversely as the temperature between −182° and the melting-point.
Other Diamagnetics.—The following table gives Curie’s determinations (Journ. de Phys., 1895, 4, 204) of the specific susceptibility Κ of other diamagnetic substances at different temperatures. It should be noted that Κ = κ/density.
| Substance | Temp. °C. | −Κ × 106. |
| Water | 15-189 | 0.790 |
| Rock salt | 16-455 | 0.580 |
| Potassium chloride | 18-465 | 0.550 |
| Potassium sulphate | 17-460 | 0.430 |
| Potassium nitrate (fusion 350°) | 18-420 | 0.330 |
| Quartz | 18-430 | 0.441 |
| Sulphur, solid or fused | 18-225 | 0.510 |
| Selenium, solid or fused | 20-200 | 0.320 |
| Selenium, fused | 240-415 | 0.307 |
| Tellurium | 20-305 | 0.311 |
| Bromine | 20 | 0.410 |
| Iodine, solid or fused | 18-164 | 0.385 |
| Phosphorus, solid or fused | 19-71 | 0.920 |
| Phosphorus, amorphous | 20-275 | 0.730 |
| Antimony, electrolytic | 20 | 0.680 |
| Antimony | 540 | 0.470 |
| Bismuth, solid | 20 | 1.350 |
| Bismuth, solid | 273 | 0.957 |
| Bismuth, fused | 273-405 | 0.038 |
For all diamagnetic substances, except antimony and bismuth, the value of Κ was found to be independent of the temperature.
Paramagnetic Substances.—Experiments by J. S. Townsend (Phil. Trans., 1896, 187, 533) show that the susceptibility of solutions of salts of iron is independent of the magnetizing force, and depends only on the quantity of iron contained in unit volume of the liquid. If W is the weight of iron present per c.c. at about 10°C., then for ferric salts
106κ = 266W − 0.77
and for ferrous salts
106κ = 206W − 0.77,
the quantity −0.77 arising from the diamagnetism of the water of solution. Annexed are values of 106κ for the different salts examined, w being the weight of the salt per c.c. of the solution.
| Salt. | 106κ + 0.77 | Salt. | 106κ + 0.77 |
| Fe2Cl6 | 91.6w | FeCl2 | 90.8w |
| Fe2(SO4)3 | 74.5w | FeSO4 | 74.9w |
| Fe2(NO3)6 | 61.5w |