Experiments and Obfervations . , c 
To try this property in a different and more convincing way, 
I heated a large iron nail till it was white hot, and in that ifate 
placed it upon an earthen fupport near one pole of the mag- 
netic needle, fo as to lie not in the fame direction, but on one 
fide of it. Then, looking attentively on the graduated circle of 
the compafs, I obferved, that the needle was not in the lead: 
moved from its natural fituation, whilft the nail remained red- 
hot ; but, as foon as the rednefs began to difappear, the needle 
advanced towards the nail, and a few feconds after the needle, 
pointed diredtly towards it. 
I tried whether in this experiment any difference was occa- 
fioned by the magnets being natural or artificial but, as it 
might be expedted, there was none. 
In purfuance of thofe magnetic experiments wherein heat 
is concerned, I tried the effects which took place when the 
magnet was heated ; but as the diminution of its power by 
heating, and an increafe of it by cooling, were obferved and 
defcribed by the late Mr. Canton, I fhall only add a circum- 
ftance, which may perhaps be new. It is that an artificial 
magnet, after having had its power diminifhed by heating, does 
not recover it intirelv again by cooling; having conftantly 
found, that the magnets which had been heated, after cooling 
would never hold as great a weight of iron as they did before. 
The heat to which thofe magnets were expofed never exceeded 
that of boiling water. This was rendered more evident by the 
following experiment. 
A magnetic bar was placed in an earthen veffel at fome 
diftance from the fouth pole of the needle of a very good com- 
pafs ; by the adtion of which magnet that end of the needle 
was drawn feveral degrees from the magnetic meridian, or the 
dire&ion in which it flood before. In this fituation of the 
apparatus 
