SMELL. 397 



smell, are certain effluvia, or particles of ex- 

 treme tenuity, which are disseminated very 

 quickly through a great extent of atmospheric 

 air. It is exceedingly difficult to conceive how 

 matter so extremely rare and subtile as that 

 which composes these odorous effluvia can re- 

 tain the power of producing any sensible im- 

 pression on the animal organs ; for its tenuity is 

 so extraordinary as to exceed all human com- 

 prehension. The most copious exhalations from 

 a variety of odoriferous substances, such as musk, 

 valerian, or assafoetida, will be continually ema- 

 nating for years, without any perceptible loss 

 of weight in the body which supplies them. It 

 is well known that if a small quantity of musk 

 be enclosed for a few hours in a gold box, and 

 then taken out, and the box cleaned as carefully 

 as possible with soap and water, that box will 

 retain the odour of musk for many years ; and 

 yet the nicest balance will not show the smallest 

 increase of its weight from this impregnation. 

 No facts in natural philosophy afford more 

 striking illustrations of the astonishing, and 

 indeed inconceivable divisibility of matter, than 

 those relating to odorous effluvia. 



It would appear that most animal and vege- 

 table bodies are continually emitting these subtle 

 effluvia, of which our own organs are not suffi- 

 ciently delicate to apprize us, unless when they 



