22 ME. J. REGINALD ASHWORTH: 
was boiled for three and a half hours in two stages, and a week later the coefficient 
was exactly the same as before. It was now laid aside for a month, when the 
coefficient was found to have changed from +0'000015 to —O'OOOOII, and this again 
slowly altered for twelve months, and became finally nearly steady at — 0’000047, 
which is less than a half of 1 j^er cent, for 100° C. The intensity had also changed, 
at first quickly, but latterly very slowly. Here it is interesting to notice that at any 
stage heating and cooling through a range of 80° or 90° diminishes the intensity in 
the later tests to a very trifling extent, but the undisturbed action of time produces 
a very slow but steady diminution to the final limit; and this recalls the circumstance 
mentioned j^reviously, how the action of time alone alters the molecular structure of 
steel so that its drawing qualities are greatly improved (§ 7). 
The magnet was now remagnetised (July 11th, 1898), which immediately raised 
the intensity from 221’7 to 474'8, a value practically identical with its initial intensity; 
after a series of heatings and coolings, with boiling at intervals, the magnet was laid 
aside, its coefficient then (October 14th) being + 0•000007, and the intensity 306‘9. 
At the same time another piece of H 30 wire was cut so as to be 8 centims. long, 
magnetised and tested. Its intensity initially was 474'7 and its coefficient +0’000033. 
After a number of heatings and coolings, remagnetisation and boiling for several hours, 
it was tested again, and laid aside for comparison with the former. Its coefficient was 
then + 0‘000032, and the intensity 333‘9 (Table VII.). Both these magnets were 
tested in June and November, 1899, and again in April, 1900. It appears that in 
the summer of 1899 the coefficients were larger than seven months previously, and 
reached a maximum of + O'OOOOGl and + 0’000076, and that since then they have 
become a little less, and now (April, 1900) stand at + 0‘000042 and + 0'000059. 
The intensity after heating and cooling has only fluctuated to the extent of 
3 per cent. 
Both these magnets are almost exactly alike in all tlie details of their behaviour, 
and it will be noticed that the second magnet when magnetised and immediately 
remagnetised, without any long interval between the magnetisations as with number 
one, arrives at once at the same condition as the first. 
18. Magnets made from this wire with a larger dimension ratio would have higher 
intensities and yield still more constant results, but then the coefficients would depart 
considerably from zero, because of the too small demagnetising factor. If, however, a 
longer piece of the wire be taken, a part of its abnormal pro^^erties can be removed 
by heating to a suitable temperature and quenching, as already shown,and thus a 
zero coefficient can be obtained with a smaller deman’iietisiiiP' factor. 
cv O 
Two lengths of 12 centims. each were cut from the same kind and thickness of 
wire as before, and were heated until just red-hot and quenched in water; they were 
then magnetised and repeatedly heated and cooled. The coefficient was negative and 
in magnitude —0'000044, and the intensity about 670 for both, the original intensity 
* ‘Roy. Soc, Proc.,’ vol. 62, p. 215. 
