266 HISTORY OF 



ceive and return their share ; and animals that, by 

 living upon, consume this general store, are found 

 to give it back in greater quantities, when they 

 die.* The air, therefore, that we breathe, and up- 

 on which we subsist, bears very little resemblance 

 to that pure elementary body which was described 

 in the last chapter ; and which is rather a sub- 

 stance that may be conceived, than experienced to 

 exist. Air, such as we find it, is one of the most 

 compounded bodies in all nature. Water may be 

 reduced to a fluid every way resembling air, by 

 heat ; which, by cold, becomes water again. 

 Every thing we see gives off its parts to the air, 

 and has a little floating atmosphere of its own 

 round it. The rose is encompassed with a sphere 

 of its own odorous particles ; while the night- 

 shade infects the air with scents of a more un- 

 grateful nature. The perfume of musk flies off 

 in such abundance, that the quantity remaining 

 becomes sensibly lighter by the loss. A thousand 

 substances, that escape all our senses, we know to 

 be there ; the powerful emanations of the load- 

 stone, the effluvia of electricity, the rays of light, 

 and the insinuations of fire. Such are the va- 

 rious substances through which we move* and 

 which we are constantly taking in at every pore, 

 and returning again with imperceptible discharge ! 

 This great solution, or mixture of all earthly 

 bodies, is continually operating upon itself, which, 

 perhaps, may be the cause of its unceasing mo- 

 tion ; but it operates still more visibly upon such 



* Boyle, vol. ii. p. 593. 



