Experiments and Obfervations . 
men. They may then be polifhed, after which they may be 
rendered more frongly magnetic by the ufual method of 
touching them with other magnetic bars ; whereas it is a very 
laborious operation to render magnetic large bars of hardened 
feel from the very beginning, viz. when they have none of 
that power. 
In the courfe of performing thofe trials, I frequently ob- 
ferved, that the pieces of Heel, whilf they were red hot, 
feemed not to be attracted by the magnets ; fo that the lead 
fhock, and even the pouring of the water, could remove them 
from the proper fituation, which rather lurprifedme; becaufe 
it has been afferted, by fome authors, that the magnet attracts 
red-hot iron as well as cold. Kircher efpecially fays, that he 
tried the experiment *, and found that a piece of iron heated fo 
as to be hardly difcerned from a burning coal, was attracted by 
the magnet as eafilv as when cold ; and he even afiigns a reafon 
why the power of a magnet is defrayed by a great degree of 
heat; whereas the red heating of the iron will not prevent its 
being attracted by the magnet. The reafon he gives is, that 
the fire corrupts and calcines the magnet, but purifies the iron. 
The following experiments were made in order to afcertain this 
matter. 
I kept a piece of feel in the fire till it was quite red hot, 
and in that fate prefented the magnet to it, fo as to touch it 
repeatedly in various places ; but no fign of attraction could be 
perceived before the rednefs difappeared. I mean, however, 
fuch rednefs as may be evidently feen in the clear daylight ; 
for, as was fhewn by other experiments, when the magnet 
begins to attract the heated iron, the rednefs of the latter can 
fill be feen in the dark. 
* fte Magnete, lib. I. p. II. theorem xxxi. 
Having 
