474 Mr, Babbage and Mr, Herschel's account of the 
scarcely more powerfully set in rotation than seemed fairly 
attributable to the quantity of its alloy. 
12. The examination of mercury presented peculiar in- 
terest from its fluidity, and the facility with which iron might 
be excluded from the experiment ; to make which, a flat 
ring of box- wood was cemented with wax between two cir- 
cular glass discs, so as to form a hollow cylinder, 2 inches in 
internal diameter, and 0.10 in its interior height. This being 
suspended, empty, by a long delicate silk thread over the 
horse-shoe magnet, was not in the slightest visible degree 
affected by its rotation, however long continued. It was 
then detached and filled with mercury, which, from having 
been thrice distilled, and afterwards having stood upwards 
of a twelvemonth in a bottle in contact with a solution of the 
nitrate of that metal, might assuredly be regarded as abso- 
lutely free from iron. Being again suspended as before, it 
now readily, though feebly, obeyed the rotation of the mag- 
net in either direction, being fully commanded by it, and set 
in motion, stopped, or reversed in its gyrations at pleasure 
by merely continuing or changing properly the motion of 
the magnet. This experiment was witnessed, among others, 
by our illustrious President, The place which mercury ap- 
pears to hold in the scale of magnetic energy was judged to 
be between antimony and bismuth, certainly superior to the 
latter, and certainly inferior to lead. 
13. In wood, glass, wax, rosin, sulphur, sulphuric acid, 
water, &c. we have not hitherto succeeded in obtaining un- 
equivocal traces of magnetism. The experiment with unan- 
nealed glass succeeded no better than with annealed. In the 
case only of one non-metallic body (unless a minute portion 
