and that the latter cannot be completely destroyed.
Hence, in accordance with the chemical nature and physiological
influence of these miasma, they would exert a marked action on the
animal economy, and cause diseases among the greater number of those
who breathe the infected air. But numerous experiments prove that, as
a rule, the air contains free ozone, though in very variable
proportions; from which we may conclude that no oxidizable
miasm--sulphuretted hydrogen, for example--can exist in such an
atmosphere, any more than it could exist in air containing but a trace
of chlorine.

'I do not know if it be true, as has been advanced by Mr Hunt and
other persons, that ozone is deficient in the atmospheric air when
some wide-spread malady, such as cholera, is raging. In any case, it
would be easy, by means of the prepared paper, to determine the truth
or fallacy of this opinion.

'There is one fact which should particularly engage the attention of
physicians and physiologists, which is, that, of all seasons, the
winter is distinguished by the greatest proportion of ozone; whence it
follows, that during that season the air contains least of oxidizable
miasma. We can say, therefore, with respect to this class of miasma,
that the air is purer in winter than in summer.

'All my observations agree in shewing, that the proportion of ozone in
the air increases with the height; if this fact be general, as I am
disposed to believe, we must consider the upper regions of the
atmosphere as purer, with regard to oxidizable miasma, than the lower.

'The appearance of certain maladies--intermittent fever, for
example--appears to be connected with certain seasons and particular
geographical conditions. It would be worth while to ascertain, by
ozonometric observations, whether these physiological phenomena have
any relation whatever with the proportion of ozone contained in the
air in which they occur.

'Considering the obscurity which prevails as to the cause of the
greater part of diseases, and the great probability that many among
them owe their origin to the presence of chemical agents dispersed in
the atmosphere, it becomes the duty of medical men and physiologists,
who interest themselves in the progress of their science, to seize
earnestly all the means by which they may hope to arrive at more exact
notions upon the relations which exist between abnormal physiological
phenomena and external circumstances.'

Such is a summ