68 Mr. Cav allots Magnetkal 
to become red-hot* by which means it was fattened, and when* 
cold being- prefen ted to the fulpended needle, its magnetifm 
was found to be entirely gone.. Hammering made it again mag-~ 
netic. Softening by fire took the magnetifm away a fecond 
time ; and thus the magnetifm was repeatedly given it by 
hammering, and was deftroyed by foftening; fometimes {hew- 
ing to have acquired a fetifible degree of that power, ev®tt 
after, two or three ftrokes of the hammer, 
E X P E .R I M B N T Ili 
The refult of the firft experiment would naturally induce 
one to fufpeft, that the hammer and anvil might have im- 
parted fome ltnall quantity of ft eel 1 to the brafs, which ren- 
dered it magnetic; and that this magnetifm was deftroyed 
in foftening the brafs, infomuch as the fire calcined the final I 
quantity of fteel that had adhered to it. In confequence of 
which confideration, I took other pieces of brafs befides that 
u fed before, and hammered them between card-paper, chang- 
ing the pieces of paper as often as was neeeffary, fince they' 
were eafily broken by the. hammer; but the pieces of braft 
became conftantly magnetic by the hammering, and their mag- 
netifm was deftroyed by fire.; 
In this experiment I generally gave to the brafs not above 
thirty ftrokes with the hammer. 
* x p E R I. M E n T lit:. 
Still fufpe&ing that the hammer and the anvil might have 
imparted fome fmall quantity of iron to the brafs, becaufe the 
pieces of card^paper fometimes were broken by the firft or 
fecond 
