that furround us. They warm the earth , and air,we fay; that is, they convey to the earth and theair the power of exciting that Senfation in our bo-dies. A common fire produces, in the fame man-ner, ail the fame efleets; though the fphere of itsaftion is confined within much narrower limits.
The odoriferous body, which is generally tooat fome diftance from us, is fuppofed to aft uponour organs by means of certain fmall particles ofmatter, called Effluvia, which being fent forth inall poffible direftions, and drawn into our noftrilsby the infpiration of breathing, produce there theSenfation of Smell. The minutenefs of thofe fmallparticles of matter, however, muft furpafs all hu-man comprehenfion. Inclofe in a gold box, fora few hours, a fmall quantity of mufk. Take outthe mufk, and clean the box with foap and wa-ter as carefully as it is poffible. Nothing can befuppofed to remain in the box, but fuch effluviaas, having penetrated into its interior pores, mayhave efcaped the effefts of this cleanfing. Thebox, however, will retain the fmell of mufk formany, I do not know for how many years ; andthefe effluvia, how minute foever we may fuppofethem, muft ,have had the powers of fubdividingthemfelves, and of emitting other effluvia of thefame kind, continually, and without any interrup-tion, during fo long a period. The niceft balance,however, which human art has been able toinvent, will not fliow the fmalleft increafe ofweight in the box immediately after it has beenthus carefully cleaned.