CHEMICAL AFFINITY. 37 



cessively to consider the innumerable links of 

 union which connect these together, and which, 

 as a whole, constitute the beautiful scheme of the 

 chemistry of creation. 



If a piece of polished iron is left in the open 

 air, and is slightly moistened, we all know that 

 it will very shortly rust, turning quite brown. 

 Why does the iron rust? It is, because it, 

 as an element, has a certain attraction for an- 

 other element which is oxygen; so much so, 

 that when they are placed together in favour- 

 ing circumstances they will unite, or join to- 

 gether, so as to form a new substance the 

 rust. A certain unseen power draws the two 

 elements together, and retains them by the 

 closest bond in a new condition of union. 

 This power or attraction is called Chemical 

 Affinity. Each of the elements is under the 

 influence of this power ; that is, every element 

 has a tendency to unite with one or more of 

 the other elements ; some with a greater, some 

 with a smaller number. The iron unites with 

 the oxygen because it is thus influenced. It 

 is now found to be a general rule, that the 

 more unlike to each other in their chemical 

 properties bodies are, the stronger is their 

 tendency to unite with one another. The 

 tendency to unite between oxygen and iron is 

 very powerful indeed; for these two elements 



