184 Mr. Herschel on certain motions produced in 
positive energy. Bismuth, silver, and gold, though present 
in considerable quantities in the mercury, impart to it no 
power of rotation whatever. 
39. This property then of the metals, bears an evident re- 
lation to their electro-positive energies. It even affords some- 
thing like a numerical estimate of them ; rude indeed, and 
liable to a thousand objections, but still not without its value 
in our present state of complete ignorance on that most inter- 
esting of all chemical problems. If it be true, that the whole 
of chemistry depends on electrical attractions and repulsions, 
every thing which offers a prospect, however remote, of one 
day arriving at an exact knowledge of the intensities of these 
forces, must be regarded as of consequence. It may be ob- 
jected, that it is only the excess of the electro-positive energy 
of the alloying metal over that of the mercury, or the alloy 
over the liquid, that we measure in these experiments, by 
the quantity of it required to impart a certain appreciable mo- 
mentum. Yet it is something to have rendered it probable, 
that this excess in the cases of sodium, zinc, and lead, are in 
proportions not wry remote from 1,600,000; 700,000; and 
1000 ; or 1600, 700, and 1. The effect being purely me- 
chanical, even the intensity of the motive forces exerted on a 
molecule of one of these metals could be determined, did we 
know the law of its action — but at least, in our ignorance of 
this, we are sure that it must be incomparably superior to 
gravity. A mass of mercury an inch in diameter alloyed 
with — 1 — its weight of zinc, revolved with a motion so rapid 
100,000 O ’ r 
as to complete the transfer of particles floating in the liquid 
in less than a second across its surface. Now, even if we 
were to take the supposition of a uniform acceleration of the 
