however, convinced me that there was likewise some other cause
for the presence of this last substance; for it continued to
appear to the last in quantities sufficiently distinguishable,
and apparently equal in every case. I had used every precaution,
I had included the tube in glass vessels out of the reach of the
circulating air; all the acting materials had been repeatedly
washed with distilled water; and no part of them in contact with
the fluid had been touched by the fingers.

"The only substance that I could now conceive as furnishing the
fixed alkali was the water itself. This water appeared pure by
the tests of nitrate of silver and muriate of barytes; but potash
of soda, as is well known, rises in small quantities in rapid
distillation; and the New River water which I made use of
contains animal and vegetable impurities, which it was easy to
conceive might furnish neutral salts capable of being carried
over in vivid ebullition."[1] Further experiment proved the
correctness of this inference, and the last doubt as to the
origin of the puzzling chemical was dispelled.

Though the presence of the alkalies and acids in the water was
explained, however, their respective migrations to the negative
and positive poles of the battery remained to be accounted for.
Davy's classical explanation assumed that different elements
differ among themselves as to their electrical properties, some
being positively, others negatively, electrified. Electricity
and "chemical affinity," he said, apparently are manifestations
of the same force, acting in the one case on masses, in the other
on particles. Electro-positive particles unite with
electro-negative particles to form chemical compounds, in virtue