INTRODUCTION. XT 



familiar with all the processes of their art, but the workmen 

 are carefully trained in the duties allotted to them, how few 

 of our food manufacturers, from the cottier, whose little garden 

 grows potatoes and cabbages, up to the proprietor whose 

 farm of some hundred acres contains plants of different habits 

 and requiring a variety of food and treatment, are yet in 

 possession of that special knowledge which their occupation 

 requires. 



It has uniformly been found that, in all professions, the 

 men who are most successful are those who have most care- 

 fully studied the principles of their business ; and why should 

 it be different with the agriculturist? There was, indeed, a 

 time in the agriculture of this country when the virgin soil 

 gave its fruits without much skill or intelligence being 

 required for its cultivation; but that time has gone by, and 

 our exhausted fields and increasing population require that 

 the farmer, who desires to support himself by the profits of 

 his produce, should make himself acquainted with the condi- 

 tions upon which the successful cultivation of his various 

 crops depends, so that he may increase the amount of food 

 produced upon his farm at the least possible expense. 



Let us suppose that the farmer is anxious to acquire a 

 knowledge of the scientific principles of his art, his first step 

 should naturally be to make himself acquainted with the na- 

 ture of the materials upon which he operates, and of the 

 plants which it is his object to raise. To acquu:e this know- 

 ledge he must have recourse to Chemistiy. Observation 

 shows him that the acorn springs up into the oak — that the seed 

 of wheat is the parent of many stalks of gi*am — that plants 

 flourish in certain circumstances, but decay in others; and 

 that they are, therefore, dependent upon certain circumstances 

 or conditions for their growth. They cannot, like animals, 

 travel about in search of food — they are fixed to one little 

 spot of ground; from whence, then, does the acorn obtain 

 those materials which are moulded into the stately oak — 

 whence does the tiny grain of wheat procure the substances 

 to build up its tall and flinty straw, and its seeds stored with 

 nutritious food? These are questions of great interest, and to 

 which, until lately, it was not in the power of science to give 

 satisfactory answers. 



It is evident that there are only three sources from which 

 plants can procure the materials for their support, — cither 



