14 THE CULTURE OF FARM CROPS. 



carbonic acid and lime ; and these by further process, but 

 much more difficult, can be separated into carbon and 

 oxygen and the metal calcium and oxygen. If an attempt 

 is made to separate or resolve these further, it is fruitless 

 and we find these substances remain unchangeable under 

 every known chemical process ; and they remain, carbon 

 and oxygen and calcium. These ultimate unchangeable 

 substances, are called elementary bodies ; and those which 

 are formed by the union of two or more of them are called 

 compound bodies. There are now in existence sixty-five 

 known and recognized elementary substances ; but the com- 

 pound bodies which exist and are formed by combinations 

 of the elementary bodies, are infinite in their variety. The 

 rocky and earthy crust of the globe, the ocean which 

 bathes it, the atmosphere which envelopes it, the plants 

 which grow upon it, and the animals which cover the face 

 of it ; are all made up of diversified forms of matter which 

 are absolutely innumerable. A man can no more count 

 them than he can number the sand upon the sea shore. 

 It is one of those wonders of nature, which appeal so strong- 

 ly and in a manner so full of interest to the farmer as he 

 .goes about his daily labors, with observant eye and thought- 

 ful mind, that these infinitely varied forms of matter, 

 which are so to speak the raw materials from which he 

 is enabled to elaborate by his skillful use of nature's forces, 

 all the vegetable and animal products of his farm ; are 

 iade up of a few only of the sixty-five elementary sub- 

 stances, by a most intricate system of combinations. This 

 is sufficiently surprising, yet it is far more amazing 

 that nearly the entire mass of these vegetable and animal 

 products consists of, and may be resolved into one or more 

 of only four of these simple substances. 



When any vegetable or animal substance is destroyed 

 as is commonly said but more correctly decomposed, or 

 resolved into its elements by intense heat and combustion, 

 it either entirely disappears, or leaves behind it a very 

 small quantity of ash. Oils, fats, gum, sugar, starch, cotton 

 fiber, wool ; horn, hair, when burned, either disappear en- 



