compound substances formed by their union consti- 

 tute the science of Chemistry. 



From these few words concerning the nature of 

 the art and science of Chemistry it will be seen that 

 in most of the occupations that engage the attention 

 of man, Chemistry plays an important part, and in 

 few more so than in the practice of Pharmacy. 



Air, water, food, drugs and chemicals, in short, all 

 substances, are composed of a few elements. An 

 intimate knowledge of the properties of these, and 

 of the various substances they form by combin- 

 ing with each other, a knowledge of the power or 

 force by which the elements contained in those com- 

 pounds are held together, and an application of such 

 knowledge to Pharmacy, must be the object sought 

 to be attained by the learner, for whom this work 

 has been written. Of the sixty-seven known ele- 

 ments, about one-half are of pharmaceutical interest; 

 of these about two-thirds are metals and one-third 

 non-metals; the remainder are so seldom met within 

 nature as to have received no practical application 

 either in medicine or art. Before intimately study- 

 ing the elements it is desirable to acquire some gen- 

 eral notions concerning them. 



Each elementary substance has a symbol (or a 

 short-hand character), which usually is a capital let- 

 ter, or a capital and one small letter. 



It has four functions: 



1. It is a short-hand for the name of the element. 



2. It represents one atom of the element. 



3. It stands for a constant weight of the element 

 the atomic weight or combining weight. 



4. Symbols represent single and equal volumes of 

 gaseous elements. 



A Chemical Compound is one in which definite 

 weights of two or more elementary substances have 



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