PREFACE vii 



by which oxygen and chlorine were described up to 1787 

 and 1 8 10 respectively; but whenever some more familiar 

 term has been introduced into the text, the alteration has 

 been indicated by square brackets. 



The detailed descriptions of classical experiments, which 

 form a leading feature of the book, should be of value not 

 only to the student but also to the teacher of chemistry, since 

 they show not merely how the great facts of chemistry might 

 have been discovered, but the actual course of the discover- 

 ies themselves. Such information has proved of real value 

 in devising courses of instruction in elementary chemistry, 

 and forms a sure guarantee against an incorrect or illogical 

 sequence ; from this point of view the book may be com- 

 mended to those who are responsible for the training of 

 teachers, as well as to students who intend to become 

 teachers themselves. The historical method has also been 

 found to provide a complete solution of the difficult problem 

 of teaching mixed classes of students, some absolute begin- 

 ners and others with a considerable knowledge of elementary 

 text-books of chemistry. This problem is insistent in 

 training colleges and in medical schools, and is probably 

 but little less urgent in other departments of teaching. The 

 material included in the present volume has been proved, 

 by several years of actual practice, to provide a means of 

 interesting and instructing both types of students. Even 

 the laws of chemical combination acquire a new interest 

 when presented in the picturesque imagery of Proust, or 

 with some of the glow of Berzelius's early enthusiasm. 



In contrast with most of the well-known histories of 

 chemistry, the volume is provided with many illustrations, 

 especially of the apparatus used by the earlier workers. It 

 is unfortunate that large-scale copper-plate illustrations can- 

 not be reduced in exact facsimile without destroying all 

 their technical merits ; but great care has been taken that 

 the wood-blocks shall reproduce as faithfully as possible all 

 the essential features of the original drawings. Thus, 



