1822.] Philosophical Transactions for 1822, Part I. 881 
in the direction of the dip, as the measure of the disturbing 
power. 
Magnetic power. 
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Dear Steels ATC. s ce-ch a oS nslin Chae eet OD 
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It being obvious from these experiments that the intensity of 
the magnetic power was in proportion to the softness of the 
metal, the author became desirous of determining the magnetic 
relations of each variety when rendered perfectly soft by being 
heated in a furnace. With this view, bars of each substance, of 
equal size, were rendered white-hot, when it was found that their 
powers, as was anticipated, agreed nearly with each other. 
“While carrying on these experiments,” says Mr. Barlow, 
“it had been observed, both by Mr. Bonnycastle and myself, 
that between the white heat of the metal, when all magnetic 
action was lost, and the blood-red heat, at which it was the 
strongest, there was an intermediate state in which the iron 
attracted the needle the contrary way to what it did when it was 
cold, viz. if the bar and compass were so situated that the north 
end of the needle was drawn towards it when cold, the south 
end was attracted during the interval above alluded to, or while 
the iron was passing through the shades of colours, denoted by 
the workman the bright-red and red heat.” 
After noticing the results hitherto obtained relative to the 
magnetic action of heated iron, and showing how the contradic- 
tory statements on the subject.may be reconciled, by supposing 
that the observations were made with iron at different degrees 
of heat, Mr. Barlow proceeds to describe some preliminary 
experiments “on the anomalous attraction of heated iron which 
takes place while the metal retains the bright-red and red heat ;” 
and he then gives a table containing the results of a regular 
series of experiments on the subject, amounting in number to 38. 
These experiments were all made with bars of cast and of 
malleable iron inclined in the direction of the dipping needle, 
and, what is somewhat unappropriately called, the negative attrac- 
tion was found to be the greatest where the natural attraction 
was the least; that is, opposite the middle of the bar, or in the 
plane of no attraction. With the bar inclined at right angles to 
its former position, the results were not.so strongly marked 
as in the experiments just mentioned. 
Mr. Barlow shows trom experiment, that these singular effects 
