repose. Observers should also be warned
against the idea of preparing their own
ozonometric papers and their own chromatic
scales; all they can do, at present, is to
select the paper which, to their individual
eyes, affords the surest and the most easily
comparable results. This mode of measurement
must be accepted provisionally until
chemists shall discover some re-agent of ozone
which does not require the intervention of
the eye, and which shall afford the means of
imbibing or being acted upon by ozone with
swiftness and certainty.

As it is, the facts already known are
extremely curious and interesting. For
instance, ozone is found to be absent from
inhabited dwellings. Slips of ozonoscopic
paper have been kept in each of the wards
of the military hospital of Metz, for twenty-four
hours, for eight-and-forty, and even for
several days, without affording the slightest
trace of ozone, although every precaution
had been taken to render the experiment
perfectly exact; while slips of the very same
paper, hung outside the windows of the
establishment, gave seven, eight, and even
ten degrees of the ozonometric scale. Similar
experiments have been made at Versailles,
by Dr. Bérigny, with the same results. It is
impossible to avoid suspecting that a clue is
thus given to the different effects upon the
health produced by in-door exercise and
out-door exercise, by town life and country life,
by labour in a metropolitan workshop and
labour in the open fields.

That ozone, either in excess or in deficit,
in the atmosphere has an influence on the
human constitution, is proved by several
recorded observations, some of which
date so far back as eighteen hundred and
forty-five. In that year, Aarau, in Switzerland,
was afflicted with cholera. Monsieur Wolf,
the director of the Observatory at Berne,
classed the days between the fifteenth of
August and the fourteenth of October into
three groups: those in which no case of death
occurred, those in which there were only one
or two, and those in which there were three
and upwards. He found that the mean
correspondence of the reactions of ozone throughout
each of those groups of days was, for the first,
second, and third-class days respectively,
very nearly as the numbers six, five, and
four. Monsieur Wolf thence concluded that
the progress of cholera is, at least, extremely
favoured by the diminution of ozone. It is
only right to state, that other experiments
have proved less conclusive. Thus, when the
cholera was at Metz, some two years ago,
ozone (or its absence) was believed to have
had something to do with the invasion of the
epidemic. Meteorological experiments relative
to the question were ordered by the
Minister of War, but the results did not
appear to confirm the current opinion. Nevertheless,
several new data were obtained,
which are worth noticing, although they
have no reference to that special subject of
inquiry. On one bank of the Seine more
ozone is found during the night than during
the day, while on the opposite bank it is
exactly the contrary. In dry weather the
atmosphere contains less ozone than when
the sky is cloudy. This might have been
presumed, à priori, as a consequence of the
different electrical state of the air in the two
cases. Thirdly, the variations of ozone follow
very nearly the same course at Saint Cloud
and at Versailles simultaneously. It is a
curious question, whether ozone exists in the
polar regions and in countries where tempests
never occur. For the answer, we must wait
awhile. Still we may guess that amidst the
arid sands of the Great Desert, where vegetation
is rare, ozone is scanty in quantity;
within the arctic and antarctic circles, we may
presume, that the reverse takes place, because
the waters of the polar seas would furnish an
abundance of positive electricity.

In eighteen hundred and fifty–five. Monsieur
Schœbein observed at Berlin a great quantity
of ozone in the atmosphere during an
epidemic grippe, or influenza, which attacked
all persons who were predisposed to pulmonary
complaints. Dr. Bœckel noticed that
malaria always occurs when the ozonoscope
marks zero or the lowest possible degree, and
that marsh-fevers rage most severely under
exactly the same circumstances. At
Strasbourg, the appearance of the cholera
coincided with the absence of ozone, while the
decrease of the epidemic was accompanied by
the return of ozone. These observations seem to
suggest the hypothesis, that marsh-fevers
are due to miasms which have for their vehicle
the proto-carbonate of hydrogen (the gas of
the marshes), which is formed and disengaged
during summer, as every one can see for
himself by strolling through the localities, by
the muddy and stagnant waters of marshes
and ponds. Is the same vehicle likely to
distribute the poisonous germs or leaven of
cholera and other epidemics? In that case,
it is easy to conceive that the ozone, formed
during a tempest by the electric discharges,
combines instantly with this carbonated
hydrogen, and therefore neutralises it.
Consequently, the more intense is an epidemic,
the less ozone would there be present in the
air. It naturally follows that epidemic
diseases would diminish after a thunderstorm,
which, in popular language, clears the air,
and, in our present state of knowledge,
generates ozone. By parity of reason, the same
diseases would increase in intensity during
hot, close, heavy weather, exactly as
happened in Paris on that fatal day of the
summer of eighteen hundred and forty-nine,
when the heat was oppressive and suffocating,
and when such a number of victims sunk
beneath the pest. The great quantity of
ozone observed by Monsieur Schœbein
during an epidemic influenza may be
explained by the action of ozone in excess.