22 
ME. S. W. J. SMITH ON THE THERMOMAGNETIC ANALYSIS OF 
Section 
Y. The relations between the properties of nickel-iron alloys containing different percentages 
of nickel. 
§ 1. The temperatures of appearance and disappearance of magnetism in nickel- 
iron alloys. § 2. The relations between these alloys expressed in terms of 
the theory of solid solution. § 3. Possible changes below the eutectic 
temperature. § 4. The differences in the rates of appearance of magnetism 
in the different alloys. §§ 5, 6. Evidence of the connection between 
permeability and state of crystallisation; Guillaume’s experiments. 
§ 6. Experiments of Hopkinson and of Guillet. §§ 7-10. The crystalline 
structure of meteoric nickel iron. § 8. The lower limit of the Widman¬ 
statten figures. § 9. The upper limit: an interpretation of the micro¬ 
structure of the San Cristobal meteorite. § 10. Summary. § 11. The 
constitution of taenite: its mode of occurrence. § 12. Microstructure of 
taenite. §§ 13-17. Chemical analyses. § 14. The low values for the 
percentage of Ni. § 15. The intermediate values. § 16. The high values. 
§ 17. An interpretation. § 18. Plessite. § 19. The possible effect of the 
rate of cooling upon the temperature of reappearance of magnetism in 
irreversible alloys. 
VI. An interpretation of the irreversibility of nickel-iron alloys.. 
§ 1. The analogy between nickel-iron alloys and supersaturated solutions. 
Deductions from the experiments of Miers. § 2. Application to Hopkin- 
SOn’s results. §§ 3-12. Application to the experimental data of Section IV. 
§ 4. The recrystallisation during cooling of a nickel-iron alloy. § 5. The 
return to the “ magnetic ” state is gradual and extends over a wide range of 
temperature. § 6. Effects of temperature alternation after magnetism has 
partially reappeared. § 7. Relations between the temperature-coefficients 
of permeability of nickel-iron alloys and of pure iron. § 8. The temperature 
at which magnetic crystals begin to disappear. Bate of disappearance. 
§ 9. Effect of temperature alternation after partial disappearance of 
magnetism. § 10. Effect of continuous cooling to the temperature of the 
air after partial disappearance of magnetism. § 11. Effect upon the air- 
temperature permeability of interruption of cooling after partial reappear¬ 
ance of magnetism. § 12. Production of a steady state by repeated heating 
and cooling over a wide range of temperature. 
VII. The composition of the Sacramento meteorite as determined by thermomagnetic analysis . 
§ 1. The chief constituent. § 2. Evidence of the presence and relative amount of 
another constituent. § 3. Changes in the properties of the second con¬ 
stituent during the course of thermal treatment. § 4. Evidence that the 
taenite bands contain a nickel-poor constituent. § 5. The permeability 
variations below 500° C. § 6. Evidence that the taenite bands contain a 
nickel-rich constituent. § 7. Inferences from data for artificial alloys. 
§ 8. Comparison with data for the meteorite. § 9. Proof of the existence 
of magnetic gaps resulting from thermal treatment. § 10. Summary of 
conclusions with respect to taenite. §11. The lag in the appearance of 
magnetism in the taenite in its final state. § 12. The effect of thermal 
