The Class-Book of Chemistry. 67 



author's experience up to that time, the following 

 passage from the introduction is very interesting : 



Among the various occupations which require a knowl- 

 edge of chemistry to be successfully carried on, that most 

 noble, useful, and universal of all human pursuits, agricul- 

 ture, stands prominent. The farm is a great laboratory, 

 and all those changes in matter which it is the farmer's 

 chief business to produce are of a chemical nature. He 

 breaks up and pulverizes his soil with plough, harrow, and 

 hoe for the same reason that the practical chemist powders 

 his minerals with pestle and mortar namely, to expose the 

 materials more perfectly to the action of chemical agents. 

 The field can only be looked upon as a chemical manufac- 

 tory ; the air, soil, and manures are the farmer's raw mate- 

 rials, and the various forms of vegetation are the products 

 of his manufacture. The farmer who raises a bushel of 

 wheat or a hundredweight of flax does not fabricate them 

 out of nothing ; he performs no miraculous work of crea- 

 tion, but it is by taking up a certain definite portion of his 

 raw material and converting it into new substances through 

 the action of natural agents; just as those substances are 

 again manufactured in the one case into bread and in the 

 other into cloth. When a crop is removed from the field 

 certain substances are taken away from the ground which 

 differ with different kinds of plants; and if the farmer 

 would know exactly what and how much his field loses by 

 each harvest, and how in the cheapest manner that loss 

 may be restored, chemistry alone is capable of giving him 

 the desired information. To determine the nature and 

 properties of his soil, and its adaptation to various plants, 

 and the best methods of improving it ; to economize his 

 natural resources of fertility ; to test the purity and value 

 of commercial manures and of beds of marl and muck ; to 

 mingle composts and adapt them to special crops; to im- 

 prove the quality of grains and fruits; to rear and feed 



