AUTHOR'S PREFACE. 



IN placing these lectures before a wider section of the public, I 

 consider it essential to indicate the point of view from which 

 they have been prepared. I regard them as an attempt to 

 follow the development of our ideas of to-day from those that 

 were formerly current. Hence I have only gone back as far as 

 Lavoisier ; because our science assumed a new aspect in his 

 hands, and because it may be held that, as regards develop- 

 ment, we are still passing through the epoch inaugurated by 

 him. 



It has been my wish to arrange the matter of the lectures 

 in such a way that the student may be enabled to obtain a 

 survey of this portion of the history of chemistry with little 

 trouble, and at the same time so that it may serve as a guide 

 for those who may desire to engage their attention more par- 

 ticularly with special investigations in this department. On 

 this account I have expressed myself as concisely as possible, 

 whilst, on the other hand, I have supplied moderately complete 

 references to the original literature in connection with the 

 subjects treated of. A twofold result appears to me to be 



