Le texte de cette page a été corrigé et est conforme au fac-similé.
plus froid que l’air, il ne se dépose pourtant point de rosée : car elle montre qu’il en sera nécessairement ainsi, lorsque l’air sera si peu fourni de vapeur aqueuse, comparativement à sa température, que môtae, étant un peu refroidi par le contact d’un corps plus froid, il sera eucore capable de tenir en suspension toute la vapeur qui s’y trouvait d’abord suspendue. Ainsi, dahs un été très-sec, il n’y a pas de rosée, ni dans un hiver très-sec de gelées blanches[1].
- ↑ The law of causation, already so amply established, admits, howewer, of efficient additional corroboration in no less than three ways. First, by deduction from the known laws of aqueous vapour when diffused through air or any other gas ; and though we have not yet come to the Deductive Method, we will not omit what is necessary to render the speculation complete. It is known by direct experiment that only a limited quantity of water can remain suspended in the state of vapour at each degree of temperature, and that this maximum grows less and less as the temperature diminishes. From this it follows, deductively, that if there is already as much vapour suspended as the air will contain at its existing temperature, any lowering of that temperature will cause a portion of the vapour to be condensed, and become water. But, again, we know deductively, from
