PLAN OF THE WORK. 



ganized kingdom; and, in relation to them, our most interesting 

 task is, to trace the various proximate principles, in which the ele- 

 ments are combined. This part of chemistry is less splendid than 

 the preceding ; but it is fruitful in important information, and much 

 of it is applicable to common wants and occurrences. 



1. Vegetable Bodies. 



We have here only oxygen, carbon, and hydrogen, as essential to 

 the constitution of most plants ; nitrogen is found in some, and the 

 number containing it is greater than was formerly supposed ; but 

 the proximate principles are numerous and important, and the student 

 is astonished to find, that such diversified results are obtained from the 

 union, in different modes and proportions, of three or four .elements. 



2. Animal Bodies. 



The few remarks, just made, are applicable here with some quali- 

 fications. 



The same elements are found as in vegetables; and nitrogen, 

 instead of being an occasional, is nearly a constant principle. The 

 number of proximate principles is however more limited than in the 

 vegetable kingdom, but their history is instructive and important. 



All are agreed in giving a late place to the chemistry of organ- 

 ized bodies ; for it is obvious, that it would not be intelligible at an 

 earlier period. 



GALVANISM. 



It has been already stated, that this power, although mentioned 

 and described, generally, among the imponderable agents, is better 

 understood, after the student has been made acquainted with all the 

 Qther facts in chemistry. 



As a general power, its most important function is, in the decom- 

 position of bodies, ending in the transfer of their elements and prin- 

 ciples, to its respective poles. This being, in the begining, ex- 

 plained, and experimentally proved, in connexion with the history of 

 the other imponderable agents, there is no difficulty in marking and 

 understanding the polarity of each body as we proceed, and when 

 we come to present Galvanism, in form and in fulness, at the end 

 of the course, thislgeneral arrangement of both elements and prox- 

 imate principles can be recapitulated, and experimentally illustrated 

 in detail, with great advantage. 



