Experiments and Observations, 21 
to come {boner when nitrous than when vitriolic acid is ufed, 
after which limit the attraction decrenfes much fafter in the 
former than in the latter cafe, which is evidently owing to the 
metal being more eafily dephlogifticatcd and diflolved by the 
nitrous than bv the vitriolic acid. 
J 
The marine acid was tried next; but, notwithftanding all 
the precautions 1 could take, it always occafioncd a very weak 
effervefcence, and the needle was not in the leaft affeCted bv it. 
A flrong efrervefcence feems to be neceflary to increafe the 
attraction between the magnet and iron or fteel ; for when I 
tried the experiment by putting a fmall quantity of acid into 
the veflel, the efferveicence was exceedingly weak ; the mag- 
netic needle was not at firft affeCted by it, but feveral hours 
after it flood a little farther from the pot, which was evidently 
owing to the dephiogiftication of the iron. 
After obferving the aCtion of acids on iron, I next tried to 
decompofe that metal by means of fire, to oblerve what effcCt 
would take place with refpeCt to its magnetifm. For this pur- 
pofe two ounces of iron flings were mixed with an ounce of 
flowers of fulphur and an ounce of nitre. This mixture was 
put into a fmall and {hallow earthen veflel, and was placed near 
the fouth extremity of the magnetic needle, which attracted 
the needle nearer than its natural fituation by about one degree 
and a half. A pane of glafs was interpofed between the mag- 
netic needle and the veflel. Things being thus dilpoied, the 
mixture was fired, and it burned rather (lowly, the fire fome- 
times going out, fo as to require being fired again ; till at laft it 
would burn no longer. During this combuflion the needle was 
once attracted fomewhat nearer ; but its motion that way was 
fo little, that I could not be quite certain of it. This happened 
not long after the fire was firft communicated to the mixture, 
after 
