To conclude this Part of our Discourse; I think it a sufficient Confirmation of this Reasoning, that in _Frogs_ kill’d in this _Grotta_, the _Bladders_ of the Lungs (more visible otherwise and distinct in these Creatures than in most others), were found subsided, and quite empty of Air (161). But if any one desires a farther Proof, he may, according to these Principles, make (as _Lionardo di Capoa_ (162) did) an Artificial _Mephitis_; for if _Antimony_, _Bismuth_, or any other such Mineral be finely powdered, and moistened with _Aqua Fortis_, or _Spirit_ of _Nitre_, there will arise a great Heat, and a thick dark Smoak, in which, as in the _Grotta de Cani_, Torches are extinguish’d, and Animals, tho’ but slowly, stifled and kill’d. And this Effect will be more sensible, and equal to the most Violent _Mephites_, if the _Antimony_ or _Marcasite_ be mix’d with _Bitumen_, and the _Spirit_ of _Nitre_, or _Aqua Fortis_, intirely depurated from all its _Phlegm_. * * * * * And thus I have shewn how Death may enter at the Nostrils, tho’ nothing properly _Venomous_ be inspired. It were perhaps no difficult Matter to make it appear, how a lesser Degree of this Mischief may produce Effects, tho’ seemingly very different from these now mention’d, yet in reality of the same Pernicious Nature; I mean, how such an alteration of the common Air as renders it in a manner _Mephitical_, that is, increases its _Gravity_, and lessens its _Elasticity_, (which is done by too much Heat, and at the same time too great a Proportion of watery and other grosser Particles mixt with it) may be the Cause of _Epidemic_ Diseases, and, it may be, more especially of those, which by Reason of their untoward Symptoms, are usually call’d _Malignant_. For it is very Remarkable, that _Hippocrates_ (163) observ’d the Constitution of the Air, which preceded _Pestilential_ Fevers, to be great _Heats_, attended with much _Rain_ and Southern Winds; and _Galen_ (164) takes Notice, that no other than a _moist_ and _hot_ Temperament of the Air brings the _Plague_ it self; and that the Duration of this Constitution is the Measure of the Violence of the Pestilence. _Lucretius_ (165) is of the same Mind, for in his admirable Description of the _Plague_ of _Athens_, These _Diseases_, says He, _either come from the Air, or arise from the Earth_, ――_Ubi_ Putrorem humida _nacta est Intempestivis_ Pluviisq; _&_ Solibus _icta_. In short, the general _Histories_ of _Epidemic_ Distempers, do almost constantly Confirm thus much, and would have done it more, if the vain Notion of _Occult Venoms_ had not prepossess’d the Minds of Authors, and made Them regardless of the manifest Causes.