VI INTRODUCTION 



feeding of animals and men. Before these subjects can 

 be considered in an intelligent way, a fundamental knowl- 

 edge must be obtained of some of the basic principles and 

 laws of chemistry > since they are as essential to future 

 work along special lines, as is a good foundation to a 

 building, or a scaffold during its construction. In the 

 household, arts, industries, and professions, constant 

 use is made of products formed from the soil, air and 

 water. In order to understand more perfectly the nature 

 of the substances dealt with so as to make the most intel- 

 ligent use of them, it is necessary to have a practical 

 knowledge of some of the laws of chemistry and of the 

 properties of the elements and compounds which enter 

 into the composition of plant and animal bodies. 



To the student who begins the study of chemistry, it 

 is imperative that the first part of the subject be thor- 

 oughly mastered. Chemistry is different in its nature 

 from many subjects. It cannot be studied in discon- 

 nected parts but must be undertaken systematically. It 

 cannot be absorbed by listening to lectures r but must be 

 studied. If the first part of the work is neglected, a 

 failure is almost inevitable. If particular attention is 

 given to the elements and their combinations, to the com- 

 position of matter, to laboratory manipulations, and 

 to the classification of the elements, and if the experi- 

 ments are performed regularly, the student experiences a 

 keen enjoyment in the subject, the work ceases to be 

 drudgery and becomes a pleasure. 



The student should make an effort to learn how to 

 study ; the memorizing of chemical formulas and equa- 



