AUTHOR'S PREFACE 



TO 



THE FIFTH EDITION 



THIS work was written during the years 1868-1870, its object 

 being to acquaint the student not only with the methods of ob- 

 servation, the experimental facts, and the laws of chemistry, but 

 also with the aspect of this science towards the invariable sub- 

 stance of varying matter. If the facts themselves include the 

 person who observes them, then how much more inevitable is the 

 reflection of personality in giving an account of methods and of 

 philosophical speculations ? For the same reason there will inevi- 

 tably be much that is subjective in every objective exposition of 

 science. And as an individual production is only significant in 

 virtue of that which has preceded and which surrounds it, so it 

 essentially resembles a mirror which in reflecting exaggerates the 

 size and clearness of neighbouring objects, and causes a person 

 near it to see reflected most plainly those objects which are 011 the 

 side to which it is directed. Although I have endeavoured to make 

 my book a true mirror directed towards the domains of chemical 

 transformations, yet involuntarily those influences near to me have 

 been the most clearly reflected, the most brightly illuminated, 

 and have tinted the entire work with their colouring. In this 

 way the chief peculiarity of the book has been determined. Ex- 

 perimental and practical data occupy their place, but the philo- 



