452 



TABLE 467.— MAGNETIC PROPERTIES OF VARIOUS TYPES OF IRON 



AND STEEL 



From tests made at the National Bureau of Standards. B and H are measured in cgs units. 



Values of B 2000 4000 6000 8000 10,000 12,000 14,000 16,000 18,000 20,000 



Annealed Norway iron.H .81 1.15 1.60 2.18 3.06 4.45 7.25 23.5 116. — 



fi 2470 3480 3750 3670 3270 2700 1930 680 150 — 



Cast semi-steel H 2.00 2.90 4.30 6.46 9.82 15.1 24.9 50.5 135. 325. 



M 1000 1380 1400 1240 1020 795 563 317 133 62. 



Machinery steel H 5.0 8.8 13.1 18.6 25.8 35.8 50.5 76.0 142. -, 



n 400 455 460 430 390 340 280 210 127 — 



Very pure iron \ H 3.30 4.48 6.35 9.10 13.0 18.9 28.8 47.0 103. 240. 



as received / p 606 893 945 880 770 635 486 340 175 83 



Annealed in vacuo) ....H .46 .60 .80 1.02 1.38 2.00 3.20 11.3 72.0 194. 



from 900°C J n 4350 6670 7500 7840 7250 6000 4380 1420 250 103 



As received //»., 150, B max 18,900, B r 7,650, H c 2.8. 



After annealing H m „ 150, B ma * 19,500, H c .53, 



TABLE 468.— MAGNETIC PROPERTIES OF ELECTRICAL SHEETS 



From tests made at the National Bureau of Standards. B and H are measured in cgs units. 



Values of B 2000 4000 6000 8000 10,000 12,000 14,000 16,000 18,000 20,000 



Dynamo steel H 1.00 1.10 1.43 2.00 3.10 4.95 9.20 34.0 114. — 



(i 2000 3640 4200 4000 3220 2420 1520 470 158 — 



Ordinary trans- 1 H .60 .87 1.10 1.48 2.28 3.85 10.9 43.0 149. — 



former steel J p 3340 4600 5450 5400 4380 3120 1280 372 121 — 



High silicon trans-1 ....H .50 .70 .90 1.28 1.99 3.60 9.80 47.4 165. — 



former steel J n 4000 5720 6670 6250 5020 3340 1430 338 109 — 



TABLE 469.— MAGNETIC PROPERTIES OF IRON IN VERY WEAK FIELDS 



The effect of very small magnetizing forces has been studied by C. Baur and by Lord 

 Rayleigh. The following short table is taken from Baur's paper, and is taken by him to 

 indicate that the susceptibility is finite for zero values of H and for a finite range in- 

 creases in simple proportion to H. He gives the formula k = 15 + 100H, or I = 15H -f 

 100// 2 . The experiments were made on an annealed ring of round bar 1.013 cm radius, the 

 ring having a radius of 9.432 cm. Lord Rayleigh's results for an iron wire not annealed 

 give k = 6A + 5.1H, or I = 6AH + 5.1 H 2 . The forces were reduced as low as 0.00004 

 cgs, the relation of k to H remaining constant. 



Second experiment 



SMITHSONIAN PHYSICAL TABLES 



