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II. The Thermomagnetic Analysis of Meteoric and Artificial Nickel-iron Alloys. 
By S. W. J. Smith, M.A., A.B.C.S., Royal College of Science, London . 
Communicated by Sir Arthur W. Rucker, F.R.S. 
Received November 1, 1906,—Read February 14, 1907. 
[Plates 1-2.] 
Contents. 
Section Page 
I. Description of the materials of which the thermomagnetic properties were investigated. , 23 
§ 1. Introduction. §§ 2-6. The Sacramento meteorite. § 3. Chemical analysis. 
§ 4. Spectroscopic analysis. § 5. Crystallographic analysis. § 6. Micro¬ 
graphic analysis. § 7. The nickel steel used in the comparison experiments. 
II. Preliminary measurements of permeability at the air temperature.. 27 
§ 1. Method employed. § 2. Results. § 3. Method of calculation of the perme¬ 
ability of a thick ring. § 4. Elimination of an error due to hysteresis 
effects which may occur in the ballistic method. §§ 5, 6. Effects of external 
fields. § 6. Experiments upon a wrought-iron ring. 
III. Arrangement of the apparatus for measurements of permeability over a wide range of 
temperatures.33 
§ 1. Apparatus employed. § 2. Method of deducing the temperature of the ring. 
§ 3. Method of winding the coils and description of the heating oven. 
§ 4. Relation between the temperature of the ring and the current in the 
heating coil. § 5. Evidence of the consistency of the temperature measure¬ 
ments. § 6. Constants of the ring coils as wound for the high-temperature 
measurements. § 7. Comparison of the C.G.S. values of the permeability 
at the air temperature obtained from different windings of the rings. 
IV. Permeability measurements between 0° C. and 850° C.40 
§ 1. Method of procedure. § 2. Preliminary experiments with a variable field. 
§ 3. Tabulation of results obtained with a field of constant strength. 
§§ 4-8. Description of the sequence of the observations. § 5. Meteoric iron 
(1st winding). § 6. Inferences. § 7. Meteoric iron (2nd winding). 
§ 8. Hadfield 5 • 8 per cent, nickel steel. 
VOL. CCVIII.—A 428. 
18.3.08 
