204 PROPERTIES OF AIR 



the subject more clear, I shall give JOHNSON'S 

 definition of both. 



" NATURAL," produced, or effected, by na- 

 ture not artificial bestowed by nature, not 

 acquired not forced not far fetched: dicta- 

 ted by nature following the stated course of 

 things." 



" UNNATURALS, contrary to the laws of na- 

 ture contrary to the common instincts forced ; 

 not agreeable to the real state of things ; not 

 representing nature." 



1. That in the system of nature, every sub- 

 stance which exists in it, is characterised by 

 particular attributes, which belong, and are 

 natural to it; and which distinguish it from 

 every thing else, is an incontrovertible truth* 

 It is these attributes that constitute the mate- 

 rials on which definition is founded : thus it is, 

 that mens sana in corpore sano, a sound mind 

 in a sound body, constitutes the natural condi- 

 tion of the human race ; mens insana in corpore 

 insano, an insane mind in a diseased body, it* 

 unnatural condition. It is the natural condi- 

 tion for a man to stand upon his feet unnatural 

 for him to rest upon his head ; natural for him 

 to have his arms at liberty unnatural for him 

 to be confined in a straight waistcoat ; natural 

 for the different species, to have -certain deter-^ 

 minate complexions, and forms unnatural for 



