RESEARCHES IN MAGNETISM. 
617 
place the matter beyond doubt, this solenoid was unwound, and another was applied 
which, instead of being wound on the wire itself, was wound on a glass tube inside 
of which the wire hung free. 
This new set of conditions gave results which entirely confirmed those obtained 
before, and which may therefore be described only very briefly. The magnetising 
force was not raised so far as before, as the early parts of the curves were of principal 
interest. 
The results of four series of readings are shown in Plate 65, fig. 51, as follows :— 
I. is the normal or no-load curve, taken after demagnetising with no load on. 
II. is the curve taken after first demagnetising with no load and then performing 
the cycle 0 —15 kilos. — 0 before magnetising. 
III. is the curve taken with 3 kilos, on after first demagnetising with no load, 
and then applying the loads 0 — 10 — 3 before magnetising. 
IY. is the curve taken with 3 kilos, on after first demagnetising with no load, 
and then applying the loads 0 — 10 — 0 — 3 before magnetising. 
The same differences are exhibited as in the former instance. II. shows greater 
susceptibility than I., and III. than IV. It is indeed not a little remarkable that 
such apparently trifling variations of conditions should cause the great differences 
which these curves manifest. 
§ 102. With the same wire and the glass-tube solenoid mentioned in the last 
paragraph the following additional observations were made. 
The wire was demagnetised by reversals, with no load, and then loaded with 
14 kilos, and a curve taken. The wire was then demagnetised by reversals with the 
14 kilos, on, and a second curve taken. Then the load was removed, and similar pairs 
of curves taken with 12, 10, 8, 6, 4, and 2 kilos, of load. Plate 65, fig. 52, shows the 
results. In the left-hand portion of the figure we have the curves taken with loads 
of 14, 12, 10, 8, 6, 4 and 2 kilos., when each of these loads was applied after 
demagnetisation, and no second demagnetisation took place before beginning to take 
the curve. In the right-hand portion of the figure the conditions are the same 
except that after the load was put on a second demagnetisation was performed 
before the curve was taken. 
Each curve in the latter series lies below the corresponding curve in the former, 
showing that demagnetisation after loading leaves the wire in a less susceptible 
condition than loading after demagnetisation produces. Comparing the curves of 
each group amongst themselves we see that with both modes of treatment a stress of 
8 kilos, gives, throughout the greater part of the curves’ course, a greater value to the 
susceptibility than any of the other stresses. It should be remembered that each 
kilo, of total load means an intensity of stress equal to 2'3 kilos, per sq. mm. 
§ 103. The parts of these curves near the origin lie so close to one another that 
their relative positions are not clearly shown in fig. 52, and the results of this experi¬ 
ment are better seen by plotting the same observations in the manner described in 
