1 8 Mr. Ca vaIlo’s Magnet icat 
filings, was placed near the magnetic needle, as before ; then 
fome boiling water was poured upon the filings, which heated 
them much more than the diluted vitriolic acid could have 
done ; but the magnetic needle was not moved in the leaffc from 
its original fituation. 
The fufpicion which occurred next was, whether the effer- 
vefcence might not agitate the iron filings lo as to bring a 
greater number of them to that fide of the vefi'el, which Hands 
contiguous to the magnetic needle. In order to obviate this 
objection, the experiment was repeated with a fingle piece of 
iron inftead of the filings; but as this piece of iron prefented a 
very imall furface to the diluted acid, the effervefcence was 
very weak, and of courfe the magnetic needle did not move 
when the acid was poured into the pot. At lafi, in order to 
remedy this fiecond inconvenience, arifing from the want of 
furface, I ufed a long piece of Imall Heel wire, which was 
twified in various directions, fo as to be admitted into the pot ; 
in which cafe the metal prefented a large furface to the acid, 
and it w r as not fubjeCt to be moved by the effervefcence. The 
refult was fimilar to that of the firfl experiment, viz. the 
attraction was increafed by the aCtion of the acid on the wire ; 
and here follows the particular account of the experiment. 
About fix yards of clean Heel wire, fomewhat lefs than one- 
fiftieth of an inch in diameter, being twified in various direc- 
tions, was put into an earthen vefi'el, which was placed near the 
fouth end of the magnetic needle, which in confequence of 
that was drawn from its natural fituation, viz. from 28 i° to 280°. 
After adding the diluted vitriolic acid, a firong effervefcence 
commenced, and the needle came to 279 0 47b About five 
minutes after, it Hood at 279 0 35b Five minutes after this, it 
Hood at 279 0 30b And a little after this obfervation, it ap- 
1 peared 
