[ ”7 3 
XIV. On the anomalous magnetic action of hot iron between 
the white and blood-red heat. By Peter Barlow, Esq. of the 
Royal Military Academy. Communicated by Major Thomas 
Colby, of the Royal Engineers, F. R. S. 
Read January 24, 1822. 
In consequence of certain theoretical results relative to the 
magnetic action of iron, obtained by Mr. Charles Bonny- 
castle, I was desirous of ascertaining the relative attraction 
which different species of iron and steel had for the magnet ; 
and with this view I procured two bars of each of the follow- 
ing descriptions of metal, 24 inches in length, and 1 inch and 
a quarter square, which being placed successively in the direc- 
tion of the dip, at a certain distance from the compass, the dis- 
turbance occasioned by each was carefully noted ; first with 
one end upwards, and then with the other ; and assuming 
the tangents of the angles as the measure of the disturbing 
power, I obtained the following specific results, viz. 
Mag. Pow. 
Malleable iron - - 100 
Cast iron 48 
Blistered steel soft - 67 
hard - 53 
Mag. Pow. 
Shear steel soft - - 66 
hard - - 53 
Cast steel soft - 74 
hard - - 49 
As it was obvious from these experiments, that the softer 
the iron the greater was its power, and the contrary, I was 
desirous of determining how nearly these different kinds 
of metal would approximate towards each other in their 
