326 THE KOYAL INSTITUTION. [CHAP. VI. 



Society. He attempts to revive the doctrine of Huygens 

 and Euler, that light depends upon undulations of an 

 ethereal medium. His proofs (i.e. his presumptive proofs) are 

 drawn from some strong and curious analogies he has dis- 

 covered between light and sound. 



You should fix your permanent residence in London, 

 where alone you can do what you ought instruct and 

 delight numbers of improved men. I am, my Friend, yours 

 with unfeigned esteem and respect, 



HUMPHRY DAVY. 



On January 5, 1802, a syllabus of Davy's course of 

 lectures on Chemistry was printed at the press of the 

 Eoyal Institution. He wrote for it the following adver- 

 tisement : 



It is generally admitted that the best method of teaching 

 the sciences is to begin with simple facts, and gradually to 

 proceed from them to the more complicated phenomena. 



In the following pages, which contain the outlines of a 

 course of lectures on Chemistry, an attempt has been made 

 to employ such a method. Hence the abstruse doctrines 

 concerning the imponderable fluids have been separated 

 from the history of simple chemical action, and the applica- 

 tions of the science from the science itself. The classification 

 of substances adopted is founded rather upon facts than 

 analogies, and in consequence certain bodies have been 

 placed among the simple principles which, from their resem- 

 blance to other bodies of known composition, have been 

 generally arranged in the class of compounds. This is an 

 imperfection, but on the principles assumed it could not 

 easily be avoided. And it will be fortunate for the author 

 if a discerning public should not discover many more im- 

 portant imperfections. 



Part I. 'The Chemistry of Ponderable Substances.' 



Part II. ' The Chemistry of Imponderable Substances.' 



