'Here, as in many other cases, we see nature effecting two different objects at one stroke. For if the oxidizable miasma are destroyed by atmospheric ozone, they, in turn, cause the latter to disappear, and we have seen that it is itself a miasm. This is doubtless the reason why ozone does not accumulate in the atmosphere in greater proportion than the oxidizable miasma, notwithstanding the constant formation of one and the other. 'In all times, the idea has been held, that storms purify the air, and I do not think that this opinion is ill-founded. We know, in fact, that storms give rise to a more abundant production of ozone. It is possible, and even probable, that sometimes, in particular localities, there may not be a just relation between the ozone and the oxidizable miasma in the air, 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.