PREFACE. IX 



the path of true philosophical inquiry, which pro- 

 mises to lead us to truth the proper object of 

 our research. 



In presenting this'report to the British Associa- 

 tion I feel myself bound to convey my sincere 

 thanks to Dr. Lyon Playfair, of St. Andrews, for 

 the active assistance which has been afforded me in 

 its preparation by that intelligent young chemist 

 during his residence in Giessen. I cannot suppress 

 the wish that he may succeed in being as useful, 

 by his profound and well-grounded knowledge of 

 chemistry, as his talents promise. 



DR. JUSTUS LIEBIG. 



Giessen, September 1, 1840. 



