As for ourself, we confess that, after repeating the curious experiments
of Mr. Dutrochet day after day, and scrupulously following his
directions, we have, in the presence of our results, that were exactly
identical with his, almost been tempted to believe ourself to be the
victim of some occult power, or at least of some optical illusion,
the true cause of which remained a mystery to us. Finally, after
many fruitless attempts to find a key to the enigma that engaged our
attention, the light finally dawned upon us, and then shone straight in
our eyes.

In comparing the last results of our experiments with those that we had
obtained previously, we saw, for example, that the camphor moved in the
test glasses at a level that was notably higher than that at which its
gyration took place the day before, or the day before that. And yet we
had always used the same vessels, the same water, and particles detached
from the same lump of camphor.

To what, then, could be due the difference observed between the two
levels at which we had, in the first and last place, seen the
camphor execute its movements? In the absence of any answer that was
satisfactory, we finally suspected that the difference that we had
noticed was ascribable to the fact that, after the numerous washings
that the apparatus had been submitted to in having water poured into
them to repeat the experiments, they had gradually been freed from
impurities of whatever nature they might have been, and which, unbeknown
to us, might have soiled their sides.

Starting with this idea, which was as yet a hyphothetical one, we began
to wash our hands, glasses, etc., at first with very dilute sulphuric