PROFESSOR TYNDALL ON THE DIAMAGNETIC FORCE, ETC. 9 
The masses of soft iron sketched in fig. 1 were placed upon the ends of the elec- 
tromagnet, with their points facing each other; between the points the body to be 
examined was suspended by a fine fibre, which, passing round a groove, the sub- 
stance could be raised or lowered by turning a milled head. The body was first 
suspended on the level of the points and its deportment noted, it was then slowly 
elevated, and the change of position, if any, was observed. It was finally permitted 
to sink below the points and its deportment there noted also. 
The following is a statement of the results ; the words ‘ equatorial’ (E.) and 
‘axial’ (A.) imply that the longest horizontal dimension of the substance examined 
took up the position denoted by each of these words respectively. The manner in 
which the bars were prepared is explained further on. 
Table II. 
Name of substance. 
Horizontal 
dimensions. 
Deportment 
of mass. 
Position. 
A 
( 
Between 
poles. 
Above. 
Below. 
1 . Tartaric acid 
0*5 XOT 
Diamagnetic. 
E. 
A. 
A. 
2. A second specimen 
0*4 xO-1 
E. 
A. 
A. 
3 . Red ferrocyanide of potassium 
0-6 xO'l 
Paramagnetic. 
A. 
E. 
E. 
4. A second prism 
0-9 xO-12 
A. 
E. 
E. 
5. Citric acid 
0-55 X 0-25 
Diamagnetic. 
E. 
A. 
A. 
6 . A second specimen 
0*48 XO'2 
E. 
A. 
A. 
7. Beryl 
0-45 X 0-1 
Paramagnetic. 
A. 
E. 
E. 
8 . Saltpetre 
0-6 xO-3 
Diamagnetic. 
E. 
A. 
A. 
9. Nitrate of soda 
0-6 xO -12 
E. 
A. 
A. 
10 . Sulphate of iron 
0-7 xO-15 
Paramagnetic. 
A. 
E. 
E. 
11. A second specimen 
0-6 xO-03 
99 
A. 
E. 
E. 
12 . A third specimen 
1-0 xO-13 
99 
A. 
E. 
E. 
13. Calcareous spar 
0-5 xO-1 
Diamagnetic. 
E. 
A. 
A. 
14. A full crystal 
E. 
A. 
A. 
15. Carbonate of iron 
0*5 xO-1 
Paramagnetic, 
A. 
E. 
E. 
16. Carbonate of iron powdered and compressed... 
0-9 xO-18 
99 
A. 
E. 
E. 
17. Compressed disk 
0-8 x0'08 
99 
A. 
E. 
E. 
18. Bismuth 
0-95 X 0-15 
Diamagnetic. 
E. 
A. 
A. 
19 . The same compressed 
0-7 xO-05 
99 
E. 
A. 
A. 
20. The same powdered and compressed 
0-6 xO-07 
99 
E. 
A. 
A. 
21. Cylinder of the same 
1-0 xO-15 
99 
E. 
A. 
A. 
22. Tourmaline 
2-1 xO-1 
Paramagnetic. 
A. 
E. 
E. 
23. A second specimen 
M xO-1 
99 
A. 
E. 
E. 
24. A third 
0-9 xO-1 
99 
A. 
E. 
E. 
25. Sulphate of nickel 
0-9 xO-3 
99 
A. 
E. 
E. 
26 . A second specimen 
0*6 xO-2 
99 
A. 
E. 
E. 
27 . Heavy spar 
0-38 X 0-18 
Diamagnetic. 
E. 
A. 
A. 
28. A second specimen 
0*4 xO-18 
99 
E. 
A. 
A. 
29 . Carbonate of tin powdered and compressed ... 
0-34 X 0*04 
99 
E. 
A. 
A. 
30. A second specimen 
length 6 times width 
99 
E. 
A. 
A. 
31. Ammonio-phosphate of magnesia powdered and 
compressed 
0-3 xO-06 
99 
E, 
A. 
A. 
32. A second specimen 
0*5 xO-07 
' 99 
E. 
A. 
A. 
33. Carbonate of magnesia powdered and com- 
pressed 
0*45 X 0-04 
99 
E. 
A. 
A. 
34. Sulphate of magnesia 
0-32 X 0*2 
99 
E. 
A. 
A. 
35. A second specimen 
0-25 X 0-15 
99 
E. 
A. 
A. 
36. Flour compressed 
0-24 X 0*04 
99 
E. 
A. 
A. 
37 . Oxalate of cobalt 
0-6 xO-08 
Paramagnetic. 
A. 
E. 
E. 
MDCCCLV. c 
