OF FERRUGINOUS BODIES. 247 
dip, displayed three distinct and perfect magnets, 
at its three cold parts; each having its proper 
poles as if a distinct and separate piece of iron. 
The heated parts were perfectly neutral. 
84. In the class of experiments last described, 
(80-83), the poles adjoining the heated parts of 
the iron, began to advance upon those parts as 
they gradually cooled: so that in experiment 8, 
the moveable pole advanced to the extremity of 
the bar; and in experiments 9 and 10, the move- 
able poles advanced upon one another; and 
eventually merged their forces and were lost. 
Hence just above a black heat, each had become 
one distinct magnet, as though it had been wholly 
heated ; and thus it remained whilst kept undis- 
turbed. 
85. I have already adverted to a peculiar phe- 
nomenon occasionally observed by Mr. Barlow, 
whilst carrying on his experiments on heated iron 
(48). The phenomenon in question was a deflec- 
tion of the needle in the opposite direction to 
that which it would take according to the ordinary 
magnetic state of the iron. It was observed 
when the bars were at a bright red heat, and 
would continue some seconds before the needle 
returned to the meridian. The usual, or positive 
